Standard Test Procedure RHD.bd

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Roads and Highways Department

STANDARD TEST PROCEDURES

MAY 2001

GaziSharif

Digitally signed by GaziSharif

DN: CN = GaziSharif, C = BD, O = RHD, OU = NRD Reason: I agree to 'specified' portions of this document Date: 2009.10.23 16:29:59 +06'00'

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FOREWARD

SIGNED BY

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To enable roads and bridges to be built in accordance with the Roads and Highways Department’s Technical Specifications (Volume 3 of 4 of the Standard Tender Documents), it is necessary for quality control tests to be carried out at both construction sites and regional testing centres.

The results of these tests are intended to assist the Engineer in deciding whether or not a particular item of work is satisfactory and to provide a permanent record to show the work has been carried out in accordance with the Contract Specification.

To be of use to the field engineer the results of many of the tests detailed must be submitted as soon as possible after completion of the particular item of work, as any work which does not conform with the Contract Specification may be rejected by the Engineer.

The Standard Test Procedures detailed in this document are mandatory for the quality control of roads constructed by the Roads and Highways Department. The RHD Technical Specifications when including a test make reference to this document and the tests are referred to by their section number and title, for example, STP 4.3 – Standard Compaction of Soil.

Standard Laboratory Test forms have been produced for the tests detailed in this document. Sample calculations are shown using these forms in the relevant sections of the document and copies of the blank forms are available for downloading from the Roads and Highways Department’s Internet Web Site at www.rhdbangladesh.org under the section covering Standard Test Procedures. Alternatively a computer ‘ floppy disc’ containing copies of the forms can be purchased from the Procurement Circle at RHD Sarak Bhaban, Ramna, Dhaka.

This manual covers all tests which are needed to be carried out at site or regional laboratories; however, other more specialist or complex tests may be required and these can be carried out at the Bangladesh Road Research Laboratory and in this respect, or other matters concerning these Standard Test Procedures, queries should be referred in the first instance to the Director, Bangladesh Road Research Laboratory, Paikpara, Mirpur, Dhaka.

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Table of Contents

CHAPTER 1 : DEFINITIONS, SYMBOLS AND UNITS

1.1 Scope...1.1 1.2 Terminology...1.1 1.3 Definitions ...1.1 1.4 Greek Alphabet...1.5 1.5 Symbols and Units...1.6 1.6 Conversion Factors and Useful Data ...1.6

CHAPTER 2 : SAMPLING 2.1. General ...2.1 2.2 Sampling of Soils...2.1 2.3 Sampling of Bricks...2.6 2.4 Sampling of Aggregates...2.9 2.5 Sampling of Cement ...2.12 2.6 Sampling of Concrete ...2.13 2.7 Sampling of Bitumen...2.16 2.8 Sampling of Bituminous Materials ...2.17 2.9 Preparing and Transporting Samples...2.17 2.10 Sample Reception ...2.19 2.11 Sample Drying...2.19

CHAPTER 3 : CLASSIFICATION TESTS

3.1 Determination of Moisture Content...3.1 3.2 Determination of Atterberg Limits ...3.11 3.3 Particle Size Distribution ...3.22 3.4 Determination of Organic Content...3.32 3.5 Standard Description and Classifications ...3.34

CHAPTER 4 : DRY DENSITY - MOISTURE CONTENT RELATIONSHIPS

4.1 General Requirements ...4.1 4.2 Sample Preparation...4.2 4.3 Standard Compaction using 2.5 kg Rammer ...4.8 4.4 Heavy Compaction using 4.5 kg Rammer...4.19 4.5 Vibrating Hammer Method ...4.19

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5.1 California Bearing Ratio (CBR) Test...5.1 5.2 Dynamic Cone Penetrometer (DCP) Test...5.21

CHAPTER 6 : DETERMINATION OF IN-SITU DENSITY

6.1 Introduction...6.1 6.2 Sand Replacement Method...6.1 6.3 Core Cutter Method ...6.10

CHAPTER 7 : TESTS FOR AGGREGATES AND BRICKS

7.1 Determination of Clay and Silt Contents in Natural Aggregates ...7.1 7.2 Particle Size Distribution of Aggregates...7.5 7.3 Shape Tests for Aggregates ...7.9 7.4 Fine Aggregate : Density and Absorption Tests ...7.15 7.5 Coarse Aggregate : Density and Absorption Tests ...7.21 7.6 Aggregate Impact Value ...7.26 7.7 Aggregate Crushing Value and 10% Fines Value ...7.32 7.8 Tests for Bricks...7.39

CHAPTER 8 : TESTS OF CEMENT

8.1 Fineness of Cement...8.1 8.2 Setting Time of Cement ...8.2 8.3 Compressive Strength of Cement ...8.5

CHAPTER 9 : TESTS ON CONCRETE

9.1 Slump Test ...9.1 9.2 Crushing Strength of Concrete ...9.5

CHAPTER 10 : TEST FOR BITUMEN AND BITUMINOUS MATERIALS

10.1 Bitumen Penetration Test ...10.1 10.2 Bitumen Softening Test ...10.6 10.3 Specific Gravity Test of Bitumen ...10.12 10.4 Bitumen Extraction Tests ...10.16 10.5 Flash Point and Fire Point Tests of Bitumen ...10.33 10.6 Viscosity Test of Bitumen ...10.41

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10.9 Marshall Stability and Flow ...10.60 10.10 Bulk Specific Gravity of Compacted Bituminous Mixtures Test ...10.76 10.11 Maximum Theoretical Specific Gravity of Paving ...10.81 10.12 Spray Rate of Bitumen ...10.86

CHAPTER 11 : STEEL REINFORCEMENT TESTS

11.1 General Requirements ...11.1 11.2 Tension Test of Steel Reinforcing Bar ...11.8 11.3 Bend Test of Reinforcing Bar ...11.14

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CHAPTER 1

DEFINITIONS, SYMBOLS AND UNITS

1.1 Scope

This standard sets out the basic terminology, definitions, symbols and units used in the various parts of the manual, and refers specifically to soils, although some terms may also be applicable when testing other materials.

Only the terms commonly in use and most likely to be met in the more routine tests on soils have been included.

Conversion factors and other useful data are also included.

1.2 Terminology

The following terminology applies to the soil testing standards.

1.2.1 Soil. An assemblage or mixture of separate particles, usually of mineral composition

but sometimes of organic origin, which can be separated by gentle mechanical means and which includes variable amounts of water and air (and sometimes other gases). A soil commonly consists of a naturally occurring deposit, but the term is also applied to made ground consisting of replaced natural soil or man-made materials exhibiting similar behaviour, e.g. crushed brick, crushed rock, pulverised fuel ash or crushed blast-furnace slag.

1.2.2 Cohesive soil. Soil which because of its fine-grained content will form a mass which

sticks together at suitable moisture contents.

1.2.3 Cohesionless soil. Granular soil consisting of particles which can be identified

individually by the naked eye or by using a magnifying glass, e.g. gravel, sand.

1.3 Definitions

1.3.1 Sample. A portion of soil taken as being representative of a particular deposit or

stratum.

1.3.2 Specimen. A portion of a sample on which a test is carried out.

1.3.3 Sampling. The selection of a representative portion of a material.

1.3.4 Quartering. Reducing the size of a large sample of material to the quantity required for

test by dividing a circular heap, by diameters at right angles, into four more or less equal portions, removing two diagonally opposite quarters, and thoroughly mixing the two remaining quarters together so as to obtain a truly representative half of the original mass. The process is repeated until a sample of the required size is obtained.

1.3.5 Riffling. The reduction in quantity of a large sample of material by dividing the mass

into two approximately equal portions by passing the sample through an appropriately sized sample divider (“riffle box”). The process is repeated until a sample of the required size is obtained. When dividing some coarse-grained materials a combination

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1.3.6 Dry soil. Soil that has been dried to constant mass at a temperature of 105 C to 1100C. Other drying temperatures. e.g. 600C, may be specified for particular tests.

1.3.7 Moisture content (w). The mass of water which can be removed from the soil, usually

by heating at 1050C, expressed as a percentage of the dry mass. The term water content is also widely used.

1.3.8 Liquid limit (LL). The moisture content at which a soil passes from the liquid to the

plastic state, as determined by the liquid limit test.

1.3.9 Plastic limit (PL). The moisture content at which a soil on losing water passes from

plastic state to semi-brittle solid state and becomes too dry to be in a plastic condition as determined by the plastic limit.

1.3.10 Plasticity index (PI). The numerical difference between the liquid limit and the plastic

limit of a soil :

PI = LL – PL

1.3.11 Non-plastic. A soil with a plasticity index of zero or one on which the plastic limit

cannot be determined.

1.3.12 Liquidity index (IL). The ratio of the difference between moisture content and plastic

limit of a soil, to the plasticity index :

I

L

=

w - PL

PI

1.3.13 Shrinkage limit (ws). The moisture content at which a soil on being dried ceases to

shrink.

1.3.14 Linear shrinkage (LS). The change in length of a bar sample of soil when dried from

about its liquid limit, expressed as a percentage of the initial length.

1.3.15 Bulk density (ρ). The mass of material (including solid particles and any contained

water) per unit volume including voids.

1.3.16 Dry density (ρd). The mass of the dry soil contained in unit volume of undried material : ρd = ρ

100 100 + w

1.3.17 Particle density (ρs). The average mass per unit volume of the solid particles in a

sample of soil where the volume includes any sealed voids contained within the solid particles.

1.3.18 Particle size distribution. The percentages of the various grain sizes present in a soil

as determined by sieving and sedimentation.

1.3.19 Test sieve. A sieve complying with a recognised Standard.

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1.3.21 Gravel fraction. The fraction of a soil composed of particles between the sizes of 60

mm and 2 mm. The gravel fraction is subdivided as follows :

Coarse gravel 60 mm to 20 mm

Medium gravel 20 mm to 6 mm

Fine gravel 6 mm to 2 mm

1.3.22 Sand fraction. The fraction of a soil composed of particles between the sizes of

2.0 mm and 0.06 mm. The sand fraction is subdivided as follows :

Coarse sand 2.0 mm to 0.6 mm

Medium sand 0.6 mm to 0.2 mm

Fine sand 0.2 mm to 0.06 mm

1.3.23 Silt fraction. The fraction of a soil composed of particles between the sizes of 0.06 mm

and 0.002 mm. The silt fraction is subdivided as follows :

Coarse silt 0.06 mm to 0.02 mm

Medium silt 0.02 mm to 0.006 mm

Fine silt 0.006 mm to 0.002 mm

1.3.24 Clay fraction. The fraction of a soil composed of particles smaller in size than

0.002 mm.

1.3.25 Fines fraction. The fraction of a soil composed of particles passing a 63 µm test sieve. Note that this includes all material of silt and clay sizes, and a little fine sand. For most practical purposes, the limiting sieve size can be taken to be 75 µm.

1.3.26 Voids. The spaces between solid particles of soil.

1.3.27 Voids ratio (e). The ratio between the volume of voids (air and water) and the volume

of solid particles in a mass of soil:

e = s - 1 (see 1.3.16 and 1.3.17)

d

ρ ρ

1.3.28 Porosity (n). The volume of voids (air and water) expressed as a percentage of the

total volume of a mass of soil.

n e

l =

+ e x 100 (%)

1.3.29 Saturation. The condition in which all the voids in a soil are completely filled with

water.

1.3.30 Degree of saturation (Sr). The volume of water contained in the void spaces between

soil particles, expressed as a percentage of the total voids:

S = r wρs (%) (see 1.3.7; 1.3.17; 1.3.27) e

1.3.31 Compaction. The process of packing soil particles more closely together by rolling or

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1.3.33 Maximum compacted dry density. The dry density obtained using a specified amount

of compaction at the optimum moisture content.

1.3.34 Relative compaction. The percentage ratio of the dry density of the soil to the

maximum compacted dry density of a soil when a specified amount of compaction is used.

1.3.35 Dry density / moisture content relationship. The relationship between dry density

and moisture content of a soil when a specified amount of compaction is used.

1.3.36 Percentage air voids (Va). The volume of air voids in the soil expressed as a

percentage of the total volume of the soil :

V = 1 - + w 100 100 (%) a d w w s ρ ρ ρ ρ               (see 1.3.7; 1.3.16; 1.3.17; 1.3.37)

1.3.37 Air voids line. A line on a graph showing the dry density / moisture content

relationship for soil containing a constant percentage of air voids. The line can be calculated from the equation :

ρ ρ ρ d = 1 - V 100 1 + w 100 w a s          

where, ρd is the dry density of the soil (Mg/m 3

);

ρw is the density of water (Mg/m 3

);

Va is the volume of air voids in the soil, expressed as a percentage of the total

volume of the soil;

ρs is the particle density (Mg/m 3

);

w is the moisture content, expressed as a percentage of the mass of dry soil.

1.3.38 Saturation line (zero air voids line). A line on a graph showing the dry density /

moisture content relationship for soil containing no air voids. It is obtained by putting Va

= 0 in the equation given in definition 1.3.37.

1.3.39 Limiting densities. The dry densities corresponding to the extreme states of packing

(loosest and densest) at which the particles of a granular soil can be placed.

1.3.40 Maximum density (ρdmax). The maximum dry density at the densest practicable state

of packing of particles of a granular soil.

1.3.41 Minimum density (ρdmin). The minimum dry density at the loosest state of packing of

dry particles which can be sustained in a granular soil.

1.3.42 Maximum (minimum) porosity or voids ratio. The porosity or voids ratio

corresponding to the minimum (maximum) dry density as defined above.

1.3.43 California bearing ratio (CBR). The ratio (expressed as a percentage) of the force

required to cause a circular piston of 1935 mm2 cross-sectional area to penetrate the soil from the surface at a constant rate of 1 mm/min, to the force required for similar penetration into a standard sample of crushed rock. The ratio is determined at penetrations of 2.5 mm and 5.0 mm, and the higher value is used.

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1.3.44 Penetration resistance. The force required to maintain a constant rate of penetration

of a probe, e.g. a CBR piston, into the soil.

1.3.45 Consolidation. The process whereby soil particles are packed more closely together

over a period of time by application of continued pressure. It is accompanied by drainage of water from the voids between solid particles.

1.3.46 Pore water pressure (uw). The pressure of the water in the voids between solid

particles.

1.3.47 Excess pore pressure. The increase in pore water pressure due to the application of

an external pressure or stress.

1.3.48 Swelling. The process opposite to consolidation, i.e. expansion of a soil on reduction

of pressure due to water being drawn into the voids between particles.

1.3.49 Swelling pressure. The pressure required to maintain constant volume, i.e. to prevent

swelling, when a soil has access to water.

1.3.50 Permeability. The ability of a material to allow the passage of a fluid. (Also known as

hydraulic conductivity.)

1.3.51 Piping. Movement of soil particles carried by water eroding channels through the soil,

leading to sudden collapse of soil.

1.3.52 Erosion. Removal of soil particles by the movement of water.

1.3.53 Dispersive (erodible) clays. Clays from which individual colloidal particles readily go

into suspension in particularly still water.

1.3.54 Shear strength. The maximum shear resistance which a soil can offer under defined

conditions of effective stress and drainage.

1.4 Greek Alphabet

A number of the symbols traditionally used in soils testing are taken from the Greek alphabet. This is reproduced below for reference purposes:

Capital Small Name Capital Small Name

A α alpha N ν nu B β beta Ξ ξ xi Γ γ gamma O ο omicron ∆ δ delta Π π pi Ε ε epsilon P ρ rho Z ζ zeta Σ σ sigma H η eta T τ tau Θ θ theta Y υ upsilon I ι iota Φ φ phi K κ kappa X χ chi Λ λ lambda ψ ψ psi M µ mu Ω ω omega

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1.5 Symbols and Units

The following symbols are used in the standards in the manual. The symbols generally conform to international usage. The units are those generally used. An asterisk indicates that no unit is used.

Term Symbol Unit

Moisture content w % Liquid limit LL % Plastic limit PL % Shrinkage limit ws % Plasticity index PI % Liquidity index IL * Bulk density ρ Kg/m3 Dry density ρd Kg/m 3 Particle density ρs Kg/m 3 Density of water ρw Kg/m 3 Voids ratio e * Porosity n % Degree of saturation Sr %

Percentage air voids Va %

Maximum dry density ρdmax . Kg/m

3

Minimum dry density ρdmin. Kg/m

3

Maximum voids ratio emax . *

Minimum voids ratio emin. *

California bearing ratio CBR %

Mean particle diameter D mm or µm

Percentage by mass finer than D K %

Elapsed time t minutes or second

Unconfined compressive strength qu kPa

1.6 Conversion Factors and Useful Data

1.6.1 General. The modern form of the metric system is known as the SI system.

SI is the accepted abbreviation for Systeme International d’Unites (International System of Units), the system finally agreed at an international conference in 1960.

1.6.2 Conversion factors. Conversion factors for SI and imperial units are given in Table 1.6.1.

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Imperial to SI SI to Imperial Length 1.609 0.3048 25.4 km m mm : mile : foot (ft) : inch (in) 0.6215 3.281 0.03937 Area 0.4045 0.09590 645.2 hectare (ha) m2 mm2 : acre : square foot : square inch 2.471 10.76 0.001550 Volume 0.764 0.02832 4.546 3.785 28.32 16.39 16387 m3 m3 litre litre litre ml mm3 : cubic yard : cubic foot : gallon (UK) : gallon (USA) : cubic foot : cubic inch : cubic inch 1.3089 35.34 0.2200 0.2642 0.03531 0.06102 Mass 1.016 0.4536 453.6 28.35 Mg (tonne) kg g g : ton : pound (lb) : pound : ounce (oz) 0.9842 2.205 0.03527

Density 0.01602 Mg/m3 (g/cm3) : pound per cubic foot 62.43

Force 9.964 4.448 kN N : ton force : pound force 0.1004 0.2248 Pressure 0.04788 6.895 47.88 kN/m2 (kPa) kN/m2 N/m2 (Pa) : lb f/sq ft : lb f/sq in : lb f/sq ft 20.89 0.1450 0.02089 NOTE 1 litre (L) = 1,000 cm3 = 1,000 mL 1 kN = 1,000 N 1MN/m2 = 1 N/mm2 1 tonne = 1,000 kilograms (kg) 1 kg = 1,000 grams (g) 1 kgf = 9.81 N 1 tonne f = 9.81 kN 1 Megagram (Mg)/m3 = 1,000 kg/m3 1 Megagram/m3 = 1 g/cc Examples

To convert imperial to SI, e.g. to convert feet to metres, multiply number of feet by 0.3048. To convert SI to imperial, e.g. to convert metres to feet, multiply number of metres by 3.281.

1.6.3 Useful data and information

1.6.3.1 Standard gravity. The international standard acceleration due to the earth’s gravity is

accepted as;

g = 9.80665 m/s2

although it varies slightly from place to place. For practical purposes g = 9.81 m/s2, the conventional reference value used as a common basis for measurements made on the Earth.

1.6.3.2 Mass. The kilogram (kg) is equal to the mass of the international platinum prototype

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There is no SI unit of ‘weight’. When ‘weight’ is used to mean the force due to gravity acting on a mass, the mass (kg) must be multiplied by g(9.81 m/s2) to give the force in Newton’s (N).

1.6.3.3 Density. The megagram per cubic metre (Mg/m3) is the density unit adopted for soil mechanics. It is 1000 times larger than the kilogram per cubic metre, the basic SI unit, and is equal to one gram per cubic centimetre :

1 Mg/m3 = 1 g/cm3 = 1,000 kg/m3

The density of soil particles (particle density) is expressed in Mg/m3, which is numerically equal to the specific gravity (now obsolete). Using Mg/m3, the density of water is unity.

1.6.3.4 Force. The Newton (N) is that force which, applied to a mass of 1 kilogram, gives it an

acceleration of 1 metre per second per second. 1 N = 1 kg m/s2

The kilonewton (kN) is the force unit most used in soil mechanics: 1 kN = 1,000 N

= approximately 0.1 tonne f or 0.1 ton f

1.6.3.5 Pressure and stress. The Pascal (Pa) is the pressure produced by a force of 1

Newton applied, uniformly distributed, over an area of 1 square metre.

The Pascal has been introduced as the pressure and stress unit, and is exactly equal to the Newton per square metre:

1 Pa = 1 N/m2

In dealing with soils the usual unit of pressure is kilonewton per square metre (kN/ m2), or kilopascal:

1 kN/m2 = 1 k Pa = 1,000 N/m2

The bar is not an SI unit but is sometimes encountered in fluid pressure: 1 bar = 100 kN/m2 = 100 k Pa = 1000 mb (millibars)

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Sieves to ASTM D422 BS sieve aperture size

Nearest designation Aperture size 75 mm 63 50 37.5 28 -20 14 10 6.3 5 3.35 -2 1.18 -600 µm 425 300 -212 150 -75 63 3 inch 21/2 inch 2 inch 11/2 inch -1 inch ¾ inch -3 /8 inch -No. 4 No. 6 No. 8 No. 10 No. 16 No. 20 No. 30 No. 40 No. 50 No. 60 No. 70 No. 100 No. 140 No. 200 No. 230 75 mm 63.5 50.8 38.1 25.4 19.05 9.52 4.75 3.35 2.36 2.00 1.18 850 µm 600 425 300 250 212 150 106 75 63

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CHAPTER 2

SAMPLING

2.1 General

This standard deals with the sampling of soils, bricks, aggregates, cement, concrete, bitumen and bituminous materials. A sample is a small quantity of material which represents in every way, a much larger quantity of material. In taking a sample we are not usually attempting to select the best or worst examples of the materials used but the typical material as used in the works. Sampling should therefore be done on a completely random basis and personal preferences should not be allowed to interfere with the selection.

2.2 Sampling of Soils

Samples are of one of two main types: disturbed or undisturbed.

2.2.1 Disturbed samples. Usually taken with a pick and shovel, scoop or other appropriate

hand tool, care should be taken to prevent coarse material from rolling off the sides of the tool, which will leave behind too fine a sample.

Disturbed samples can be taken in test pits, trenches or similar excavations, auger holes and boreholes. Disturbed samples can also be taken from stockpiles of material and from material laid during road construction. Small disturbed samples can also be available as the result of carrying out other work, e.g. samples from the Standard Penetration Test (SPT) shoe, and samples from the cutting shoe of undisturbed sample tubes.

2.2.1.1 Techniques. The sampling technique employed will be influenced by factors such as

the type and quantity of material being sampled, the equipment available, physical constraints of the sampling location, the intended use of the material being sampled.

2.2.1.1.1 Test pits. Based upon the changes in moisture condition, colour consistency, soil type,

structure etc., the sides of the test pit are inspected to their full depth and any observable change is recorded with depth. Any vegetation growing around the upper edge of the test pit should be removed. Now every distinguishable gravel, soil or sand layer should separately sampled by holding a spade or canvas sheet at the lower level of the layer against the side of the pit and by cutting a sheer groove to the full depth of the layer with a pick or spade. If the test pit had been dug sometimes before, then weathered material should be removed from the surface before sampling. The material obtained in this way should be placed in sample bags. The canvas sheet may also be spread out on the floor of the test pit if this is more convenient. Once all the layers have been sampled, all of the material from a particular layer must be combined on either a clean, hard, even surface or on a canvas sheet and properly mixed with a spade. The material sampled should not be contaminated with other material.

Samples should preferably be sealed in airtight tins and should fill the tin completely. Duplicate or even triplicate samples should be taken. If the bulk sample is too large, quarter or riffle out into sample bags a representative sample of the layer as explained earlier. The sample bags must be clearly and indelibly marked, so that the samples can be identified in the laboratory. All test pits should be properly fenced to safeguard villagers and animals.

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made unless:

a) It is properly propped and braced

b) The gradient of the sides is at least equal to the natural angle of repose of the soil. c) It is in firm rock.

2.2.1.1.2 Stockpiles. When sampling from a stockpile the material on the top and sides of the

pile must not be used as this is generally coarser than the interior of the stockpile. The correct procedure is to dig small holes in the stockpile (Figure 2.2.1) and sample the material from the base of these holes. At least ten holes must be made at different places on the stockpile and the materials obtained should be thoroughly mixed together. However, stockpiles are often scraped together in natural material with bulldozers, in which case it is better to wait until the stockpile has been completed before taking samples. Samples will be carried out using hand tools. Sampling can also be done using a mechanical loader-digger (in large stockpiles). Samples may be collected by using two shovels perpendicularly, one to prevent material falling on to the samples and one to clean off and take the sample (Figure 2.2.2). Samples may also be collected by digging a groove from the top to the bottom of the stockpile (Figure 2.2.3).

Table 2.2.1

Type of Test Soil Group*

Fine-grained Medium-grained Coarse-grained Moisture content Atterberg limits

Particle size distribution (sieving) Particle size distribution (sedimentation) Particle density

MDD test

California bearing ratio pH value 50 g 1 kg 150 g 250 g 1.5 kg 80 kg 6 kg 150 g 350 g 1.5 kg 2.5 kg 100 g** 2 kg 80 kg 6 kg 600 g 4 kg 2.5 kg 17 kg 100 g** 4 kg 80 kg 12 kg 3.5 kg

Mass of sample required for each test on disturbed samples is given in Table 2.2.1. These masses include some allowance for drying, wastage and rejection of stones where required. Multiply these masses by the number of tests required. Where appropriate, these masses assume that soils are susceptible to crushing.

** Sufficient to give the stated mass of fine-grained material. * Soil group

i) Fine-grained soils: Soils containing not more than 10% retained on a 2 mm test sieve.

ii) Medium-grained soils: Soils containing more than 10% retained on a 2 mm test sieve but not more than 10% retained on a 20 mm test sieve.

iii) Coarse-grained soils: Soils containing more than 10% retained on a 20 mm test sieve but not more than 10% retained on a 37.5 mm test sieve.

A soil shall be regarded as belonging to the finest-grained group as appropriate under the above definitions.

2.2.1.1.3 Road pavement layers. When sampling from a partly constructed road pavement, for

example in crushed brick consolidation work, several small areas should be marked out and all the material must be collected from the excavated holes or trenches of each area. Care must be taken to ensure all the fine material is collected by using small tools like brushes. Undisturbed samples are not generally taken in roadwork layers. Core-cutters used primarily in fine grained soils for in-situ density determination can also provide an undisturbed sample.

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Samples generally described as undisturbed can be taken in the form of excavated blocks, from which test specimens are later prepared, or in metal tubes fitted with sharpened cutting shoes. Sample tubes of this type are driven or jacked into the ground using a variety of methods and the sample are more frequently taken in boreholes using machine-operated equipment, but can also be obtained in test pits using hand-operated equipment.

2.2.2.1 Techniques

2.2.2.1.1 Block samples. Cohesive material in test pits or other locations can be sampled in

blocks by carefully cutting away surrounding material and then undercutting the block to remove it.

2.2.2.1.2 Samples in moulds and tubes. Metal tubes for taking undisturbed samples are

commonly 75 mm or 100 mm φ and 450 mm long (known as U3 or U4 tubes) or 38 mm

φ and 230 mm long. The latter are convenient for use in test pits, when they can be driven by using a hammer or preferably by a driving dolly. On ejection and trimming, the samples are suitable sizes for triaxial testing. The larger sample tubes are fitted with detachable cutting shoes and are generally driven using mechanised equipment or hand-operated hammering device. Considerable care is required to maintain the verticality of the tube when driving it. Samples in tubes or block sample should be carefully waxed after removing just enough of the top of the sample with a palette knife to form a flat surface.

2.2.3 Labeling sample. The sample must be comprehensively labeled. The label should

include information from the following list, as appropriate; a) Name of the project

b) Name of the sampler c) Date and time of sampling

d) Location within project: chainage; offset; carriageway; construction area, etc. e) Depth of sample below reference datum, e.g. finished road level

f) Sample number g) Description of the layer h) Description of the material

i) Test pit; borehole; auger hole number j) Type of sample

k) Sampling method l) Supplier’s name m) Source of material

n) Number and type of container(s), and the number(s) with which the containers are marked

o) How samples are being sent

p) Registration number of sampled truck

q) Additional information, e.g. how the material was processed before sampling. Metal tubes should be labeled on the side of the tube and not on the end cap. The end of the metal tube marking the top of the stratum should be so marked (i.e. with a T). The present system uses pre-printed ‘Sample Record Cards’, shown as Form 2.2.1.

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2.3.1 Scope. The scope of this standard is to provide methods of sampling bricks without

bias and to give guidance as to the frequency and size of samples required for testing. The physical form of the consignment of bricks will normally dictate the choice and method of sampling.

No special equipment is required for sampling bricks.

2.3.2 Sampling methods. The sample may be drawn either by a) random sampling; or b)

stratified sampling.

1. Sampling in motion

Whenever practicable a sample shall be taken whilst the bricks are being moved for example during loading or unloading. The lot shall be divided into a number of convenient portions (not less than ten) such that when equal number of bricks are drawn from each of these portions the number of bricks required for the inspection and testing is provided.

2. Stacked materials

The number of bricks required for the tests should be sampled from a consignment of not more than 15,000 units for machine-made bricks and 5,000 units for hand-made bricks. The number of bricks required for all the various tests is detailed in Table 2.2. The bricks should be sampled at random so that each brick in the stack or stacks has an equal chance of being chosen, including those bricks within the stacks. This may require the dismantling of part of the stack in order to reach the bricks inside. This will be difficult unless the stacks are small. If possible, an equal sub-sample of not more than 4 bricks should be taken from at least 6 real or imaginary similarly-sized sections of the consignment.

3. Brick soling

Bricks laid as whole bricks such as in herring bone paving or in shoulder work should be sampled from an area of one square metre marked on the road. All whole bricks within the marked area should be returned to the laboratory as one sample. Several such areas may require to be marked out in order to collect the number of bricks required for the various tests.

4. Crushed brick

Crushed brick laid as a road pavement layer should be sampled in accordance with 2.2.1.1.3. It is most important that all fine material is removed from the test hole.

2.3.3 Treatment of samples. When the sample is to provide bricks for more than one tests

the total number shall be collected together and then divided by taking bricks at random from within the total sample to form each successive sub-sample. Crushed bricks may be riffled or quartered if necessary before transportation, provided that the requirements for minimum test sample weights are met.

2.3.4 Number of bricks required

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Table 2.3.1 Number of bricks required for testing

Purpose Number of bricks required for sample

Dimensional checks Soluble salt content Compressive strength Water absorption 24 10 12 10

2.3.5 Sample identification. The following information should be clearly indicated on the

sampling certificate by the sampling personnel. a) Sampling agent

b) Contract name / work name c) Client name

d) Where the bricks will be used e) Supplier of bricks

f) Date of manufacture g) Type of brick

h) Size of consignment i) Type of test required.

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2.4 Sampling of Aggregates

2.4.1 Definitions

a) Batch. A definite quantity of some commodity manufactured or produced under conditions which are presumed uniform.

b) Sampling increment. A quantity of material taken at one time from a larger body of material. When sampling aggregates, the material taken by single operation of a scoop should be treated as a sampling increment.

c) Bulk sample. An aggregation of the sampling increments.

d) Laboratory sample. A sample intended for laboratory inspection or testing. e) Test portion. The material used as a whole in testing or inspection.

2.4.2 Equipment

a) A small scoop, to hold a volume of at least 1 L (about 1.5 kg). This scoop is used for sampling aggregates of nominal sizes less than 5mm.

b) A large scoop, to hold a volume of at least 2 L (about 3 kg.). This scoop is used for sampling any grading of aggregate but is required particularly for aggregates of nominal sizes greater than 5mm.

c) Containers, clean and non-absorbent for collecting the increments of a sample. d) Containers, clean and impervious for collecting samples for sending to the

laboratory. They should be durable and at least 100 micron thick.

e) A sample divider, appropriate to the maximum size to be handled. A riffle box is suitable or a flat shovel and a flat metal tray for use in quartering.

2.4.3 Procedure for sampling coarse, fine and all-in aggregate

a) Only an experienced person should be allowed to sample.

b) Obtain a bulk sample by collecting, in the clean containers, sufficient number of increments to provide the required quantity of aggregate for all the tests to be made. However, the number of increments should be not less than those given in Table 2.4.1.

Table 2.4.1 Minimum number of sampling increments

Nominal size of aggregate Nominal size of sampling increments Nominal size of sampling increments Approximate minimum mass for normal density aggregate kg.

Large scoop Small scoop

28 mm and larger 20 - 50

5 mm to 28 mm 10 - 25

5 mm and smaller 10 half scoops 10 10

c) Take increment from different parts of the batch in such a way as to represent the average quality.

d) When sampling from heaps of aggregates, take the required number of increments from positions evenly distributed over the whole surface of the heap.

e) When sampling from ground level, care should be taken to avoid contamination of the material.

f) When sampling form material in motion, calculate the sampling times to give the required number of sampling increments, ensuring that they are randomly distributed throughout the batch of aggregate.

g) When sampling from a falling stream of aggregate, take increments from the whole width of the stream.

h) When sampling from a conveyor belt, stop the conveyor at appropriate times and take all the material from a fixed length of the conveyor.

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then dispatch the smaller sample for testing. j) Never sample manually form a moving conveyor.

2.4.4 Reduction of sample. It is sometimes necessary to reduce the mass of bulk sample at

site substantially. This shall be done in such a way to preserve at each stage a representative part of the bulk sample. The reduction of sample should be done in accordance with 2.9.1.1.

2.4.5 Dispatching of samples. The samples should be transferred completely to containers

which shall then be sealed for dispatch. Individual packages should preferably not exceed 30 kg.

a) Information accompanying the samples.

Each sample should contain a card, suitably protected from damage by moisture and abrasion, giving details of the dispatcher and the description of the material. b) Sampling certificate

Each sample, or group of samples from a single source, shall be accompanied by a certificate, from the person responsible for taking the sample. The certificate shall include as much as is appropriate of the following information.

i.) Name of testing agent ii.) Client name

iii.) Contractor’s name iv.) Contract name

v.) Name and location of source vi.) Date and time of sampling vii.) Method of sampling viii.) Identification number ix.) Description of sample x.) Tests required

xi.) Any other information that may be useful to the tester xii.) Name and signature of sampler

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2.5.1 Introduction. In a general sense of the word, cement can be described as a material

with adhesive and cohesive properties which make it capable of bonding mineral fragment into a compact whole mass. The main components of cement are compounds of lime. One of the properties of cements is to be able to set under water by virtue of a chemical reaction with the water. In civil engineering cement is normally confined to calcareous, hydraulic cement. The variability of the proportions of the individual mineral content in the cement renders it to different behaviours in both chemical and physical. Table 2.5.1 lists a number of cements and their designation.

Table 2.5.1 Main types of Portland cement

General description ASTM description

Ordinary Portland

Rapid-hardening Portland Extra rapid-hardening Portland Low heat Portland

Modified cement Sulphate-resisting cement White Portland Slag cement Type I Type III Type IV Type II Type V Type S

2.5.2 Scope. This test provides methods for sampling hydraulic cements for testing. The

importance of sampling has already been underlined in the introduction.

2.5.3 Equipment. No special equipment is required for sampling cements other than the

following:

a) Square mouthed shovel; size 2 in accordance with BS 3388.

b) Suitable flexible container capable of collecting cement from the nozzle of a pump. c) Other suitable sealable containers.

Note. Containers to be used for sampling cement should be watertight and water resistant in order to prevent water ingressing into the sample.

2.5.4 Methods

2.5.4.1 Sampling from concrete batch plant

2.5.4.1a Bulk cement

a.1 The flexible container is fitted around the discharge nozzle of the silo and cement is allowed to flow into it.

a.2 The flexible container is fitted around the discharge nozzle of the cement haulage truck and cement is allowed to flow into it before discharge into the silo.

2.5.4.1b Bagged cement

Using the random numbers method of sampling decide on the size of a lot and take at random one bag of cement to represent that lot.

2.5.5 Rate of sampling. The rate of sampling is governed by the particular tests required by

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2.5.6 Test type requirement. For pre-construction approval of cement all tests such as

chemical composition, physical properties of: fineness, setting times and compressive strengths are normally required. Upon approval of the cement type, the supplier and manufacturer, cement is procured. The tests required to be carried out to confirm continuous quality during construction are limited due to the length of the tests, however, samples from each batch, for each type of cement, from each supplier from each delivery are taken for routine testing:

a) compressive strength b) initial and final setting times c) fineness modulus

Other physical tests and chemical tests are normally required once per month from each manufacturer, for each type of cement.

2.5.7 Sampling certificates. A sampling certificate should be issued every time samples of

cement are delivered or collected for sampling. The certificate should include at least the following information:

a) Name of testing agency b) Client

c) Manufacturer d) Client

e) Cement type f) Location of sample

g) Sample unique identification number h) Name and signature of sampler

i) Purpose of sampling (test types to be performed) j) Date of sampling

k) Any other relevant information

2.6 Sampling of Concrete

2.6.1 Scope. The purpose of this test is to provide methods which could be used on site for

obtaining from a batch of fresh concrete, representative samples of the quantity required for carrying out the required tests and for making test specimens.

2.6.2 Definitions

a) Batch. The quantity of concrete mixed in one cycle of operations of a batch mixer, or the quantity of concrete conveyed ready-mixed in a vehicle, or the quantity of concrete discharged during 1 min. From a continuous mixer.

b) Sample. The quantity of concrete, consisting of a number of standard scoopfuls, taken from a batch of concrete.

c) Standard scoopful. The quantity of concrete taken by a single operation of the scoop, approximately 5 kg mass of normal weight concrete.

2.6.3 Apparatus

a) Scoop, made from minimum 0.8 mm thick non-corrodible metals suitable for taking standard scoopfuls of concrete.

b) Container for receiving concrete from a scoop, made of plastic or metal, of 9L minimum capacity.

c) Sampling tray, minimum dimensions 900 mm x 900 mm x 50 mm deep, of rigid construction made from a non-absorbent material not readily attacked by cement paste.

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chemical composition, physical properties of: fineness, setting times and compressive strengths are normally required. Upon approval of the cement type, the supplier and manufacturer, cement is procured. The tests required to be carried out to confirm continuous quality during construction are limited due to the length of the tests, however, samples from each batch, for each type of cement, from each supplier from each delivery are taken for routine testing:

a) compressive strength b) initial and final setting times c) fineness modulus

Other physical tests and chemical tests are normally required once per month from each manufacturer, for each type of cement.

2.5.7 Sampling certificates. A sampling certificate should be issued every time samples of

cement are delivered or collected for sampling. The certificate should include at least the following information:

a) Name of testing agency b) Client

c) Manufacturer d) Client

e) Cement type f) Location of sample

g) Sample unique identification number h) Name and signature of sampler

i) Purpose of sampling (test types to be performed) j) Date of sampling

k) Any other relevant information

2.6 Sampling of Concrete

2.6.1 Scope. The purpose of this test is to provide methods which could be used on site for

obtaining from a batch of fresh concrete, representative samples of the quantity required for carrying out the required tests and for making test specimens.

2.6.2 Definitions

a) Batch. The quantity of concrete mixed in one cycle of operations of a batch mixer, or the quantity of concrete conveyed ready-mixed in a vehicle, or the quantity of concrete discharged during 1 min. From a continuous mixer.

b) Sample. The quantity of concrete, consisting of a number of standard scoopfuls, taken from a batch of concrete.

c) Standard scoopful. The quantity of concrete taken by a single operation of the scoop, approximately 5 kg mass of normal weight concrete.

2.6.3 Apparatus

a) Scoop, made from minimum 0.8 mm thick non-corrodible metals suitable for taking standard scoopfuls of concrete.

b) Container for receiving concrete from a scoop, made of plastic or metal, of 9L minimum capacity.

c) Sampling tray, minimum dimensions 900 mm x 900 mm x 50 mm deep, of rigid construction made from a non-absorbent material not readily attacked by cement

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2.6.4 Sampling procedure. Estimate the number of scoopfuls required for the test(s) by

reference to Table 2.6.1.

Note. If a shovel is used or other defined apparatus, correlate between the quantity of the scoop and the quantity of the shovel.

Note. When sampling from a batch mixer or ready-mixed concrete truck disregard the very first part and the very last part of the discharge. Preferably sample from the middle third of the batch.

Note. If the batch to be sampled has been deposited in a heap or heaps of concrete, the parts should whenever possible be distributed through the depth of the concrete as well as over the exposed surface.

Table 2.6.1 Quantities of concrete required

Test specimen number of standard scoopfuls

Slump Compacting factor Vebe time Flow index Air content Density 2 cubes 100mm x 100mm 2 cubes 150mm x 150mm 2 beams 100mm x 100 mm x 500mm 2 beams 150mm x 150 mm x 750mm 2 cylinders 150mm x 300mm 4 6 4 4 4 6 4 4 6 18 6

2.6.5 Obtaining a sample. Ensure that the equipment is clean. Using the scoop obtain a

scoopful of concrete from the central portion of each part of the batch and place it in the container or containers. When sampling from a falling stream pass the scoop through the whole width and thickness of the stream in a single operation. Take the container(s) to the area where the sample is to be prepared for testing or moulding.

Sampling from a heap of concrete. Ensure that the shovel is driven into the heap and that concrete is taken to represent the whole mass of the heap by taking a sub-sample from different areas of the heap well spaced over its entire surface area. Combine all sub-samples, agitate and mix well and prepare the sample for testing or moulding.

2.6.6 Protection of samples. At all stages of sampling, transport and handling, the fresh

concrete shall be protected against gaining or loosing water and against excessive temperatures.

2.6.7 Certificate of sampling. Each sample shall be accompanied by a certificate of

sampling from the person responsible for taking the sample and the certificate shall include at least the following information:

a) Testing agency b) Client

c) Contract name

d) Location within the structure of concrete e) Sample identification number

f) Delivery batch note number or any other means of identifying the batch g) Concrete temperature

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i) Name of sampler j) Signature of sampler

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2.7 Sampling of Bitumen

Bitumen is normally contained either in metal drums or heated bulk tanks and different methods should be used for sampling each type.

2.7.1 From metal drums the sample must be taken by cutting holes in the side of the drum and removing a sample of bitumen from these holes. Samples should not be taken from the top and bottom of the drum as this may be contaminated during storage and transport.

2.7.2 From a heated bulk tank it is necessary to obtain a sample from the full depth of the tank. This is best done from the top access opening using a purpose-made tube with a closing plug at the bottom, as shown in Figure 2.7.1. The tube is pushed into the full depth of the bitumen, the flap closed and the tube withdrawn. The sample obtained from the tube must be fully mixed before removing a portion for test.

Figure 2.7.1 Bitumen Sampling Tube

Handle

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Pre-mixed bituminous materials may be sampled at the asphalt plant or at the site where the material is being laid.

2.8.1 When sampling at the asphalt plant, the whole batch should be discharged into a lorry and then a sample taken from the material in the lorry. This is done in a similar way to sampling from a stockpile with fractions of the sample being taken from at least five different points of the material.

2.8.2 Sampling at the laying site may either be from the paving machine or the laid material.

a) When sampling from a paving machine, material should never be taken from the front hopper as segregation often takes place here. Samples should always be taken from the rear screws, a scoop being used to collect material from the ends of the screw. Samples must only be taken when the screws are fully loaded and samples should be taken from both ends.

b) When sampling the as laid material, an area to be sampled is marked out and all the material within that area, to the full layer thickness should be removed. Generally it is better to obtain a sample from a number of smaller areas than one big area. On completion of sampling, care must be taken to ensure the areas are repaired to the standard of the original material.

Samples of bituminous materials are best transported in a closed tin or small drum. The details of the sample should be recorded, including sample number, date, origin of material, type of material, time of mixing, time of laying, chainage of laid material and weather conditions. It is also necessary to record the temperature after mixing, the temperature at the time of laying and the temperature at the time of rolling.

2.9 Preparing and Transporting Samples

2.9.1 Sample preparation

Many samples will require some preparation before being sent to the laboratory for testing, particularly if their large sizes makes them difficult to handle or because they require special protection.

2.9.1.1 Sample reduction. If the sample is delivered larger than required for a particular

testing programme, it must be divided to obtain a sample of the required size. In order to ensure the test sample represents the original material, it is necessary to divide the original sample either by quartering or by using a sample divider (Riffle box).

2.9.1.1.1 Quartering. In this method the original sample is placed on a hard clean surface

(preferably concrete) and made into a neat circular pile. Using a shovel, this pile is then separated into quarters by making two lines at right angles through the centre of the pile. Two opposite quardrants should then be put aside and the remaining two quadrants should be mixed together to give a smaller sample. If the divided sample is still too large, the procedure should be repeated. Figure 2.9.1 shows the procedure diagrammatically.

2.9.1.1.2 Sample divider. A sample divider, or riffle box, is a purpose-made tool for splitting

samples and a riffle box is shown in Figure 2.9.2. The box consists of a number of slots or chutes, alternate ones leading to two separate containers. The total sample is placed into the top hopper and passes down the chutes, half of the sample being collected in

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2.8 Sampling of Bituminous Materials

Pre-mixed bituminous materials may be sampled at the asphalt plant or at the site where the material is being laid.

2.8.1 When sampling at the asphalt plant, the whole batch should be discharged into a lorry and then a sample taken from the material in the lorry. This is done in a similar way to sampling from a stockpile with fractions of the sample being taken from at least five different points of the material.

2.8.2 Sampling at the laying site may either be from the paving machine or the laid material.

a) When sampling from a paving machine, material should never be taken from the front hopper as segregation often takes place here. Samples should always be taken from the rear screws, a scoop being used to collect material from the ends of the screw. Samples must only be taken when the screws are fully loaded and samples should be taken from both ends.

b) When sampling the as laid material, an area to be sampled is marked out and all the material within that area, to the full layer thickness should be removed. Generally it is better to obtain a sample from a number of smaller areas than one big area. On completion of sampling, care must be taken to ensure the areas are repaired to the standard of the original material.

Samples of bituminous materials are best transported in a closed tin or small drum. The details of the sample should be recorded, including sample number, date, origin of material, type of material, time of mixing, time of laying, chainage of laid material and weather conditions. It is also necessary to record the temperature after mixing, the temperature at the time of laying and the temperature at the time of rolling.

2.9 Preparing and Transporting Samples

2.9.1 Sample preparation

Many samples will require some preparation before being sent to the laboratory for testing, particularly if their large sizes makes them difficult to handle or because they require special protection.

2.9.1.1 Sample reduction. If the sample is delivered larger than required for a particular

testing programme, it must be divided to obtain a sample of the required size. In order to ensure the test sample represents the original material, it is necessary to divide the original sample either by quartering or by using a sample divider (Riffle box).

2.9.1.1.1 Quartering. In this method the original sample is placed on a hard clean surface

(preferably concrete) and made into a neat circular pile. Using a shovel, this pile is then separated into quarters by making two lines at right angles through the centre of the pile. Two opposite quardrants should then be put aside and the remaining two quadrants should be mixed together to give a smaller sample. If the divided sample is still too large, the procedure should be repeated. Figure 2.9.1 shows the procedure diagrammatically.

2.9.1.1.2 Sample divider. A sample divider, or riffle box, is a purpose-made tool for splitting

samples and a riffle box is shown in Figure 2.9.2. The box consists of a number of slots or chutes, alternate ones leading to two separate containers. The total sample is placed into the top hopper and passes down the chutes, half of the sample being collected in each container. The width of the chutes shall be appropriate to the maximum particle

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size of the sample and in general should not be smaller than 1.5 times the maximum particle size of the sample

If the sample is still too large, one of the containers may be put aside and the material from the other container is passed through the sample divider again.

2.9.2 Sample transportation

All samples should be carefully packed and labeled before transporting them to the laboratory. Sample bags must be strong enough to withstand rough handling and be of a type which prevents loss of fines or moisture from the sample, e.g. thick polythene bags inside jute bags. The use of steel drums for large bulk samples could also be considered. Water samples in glass or plastic containers will require particular care in handling.

Undisturbed samples should be placed in wooden boxes and packed in sawdust or similar material to provide added protection. Collision between tubes in transit can easily damage sensitive samples.

2.10 Sample Reception

2.10.1 Registration. Full details of the sample, as written on the label is checked and

amended and weighed and must be entered in the laboratory register. A unique number is allocated to the sample and this number is used subsequently on all test sheets for the sample. A copy of the formalised testing programme should accompany the sample through the various stages of testing.

2.10.2 Initial treatment

a) Natural moisture content samples should be taken first, as quickly as possible. b) Air drying should be done by leaving the soil spread out in trays or on a hard, clean

floor in the laboratory for 2-3 days.

c) Oven drying must be done at the correct temperature (110±50C).

d) No attempt should be made to quarter down or riffle material which is in lumps or is larger than the size of the riffle-box chutes.

2.10.3 Storage. Storage of all samples should be in an orderly and systematic manner so that

they can be subsequently located easily. The storage facility itself should be a secure area, free from the risk of contamination or other harmful influences.

Undisturbed samples may be damaged by vibration or corrosion of tubes and should be stored with especial care. Tubes containing wet sandy or silty soils should be stored upright (suitably protected against being knocked over), to prevent possible slumping and segregation of water. The end caps of tube samples which are to be stored for long periods should be sealed with wax, in addition to the wax seal next to the sample itself. Samples which have been tested should not be disposed of without the authority of the laboratory section head.

2.11 Sample Drying

Many tests require the material to be drier at the start of the test than the sample as obtained from the field. Some means of drying the sample must, therefore, be utilised. In the case of liquid and plastic limit tests, it is essential that the material is air dried and, as a general rule, it is preferable to dry samples in the air as opposed to drying in

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particle size of the sample

If the sample is still too large, one of the containers may be put aside and the material from the other container is passed through the sample divider again.

2.9.2 Sample transportation

All samples should be carefully packed and labeled before transporting them to the laboratory. Sample bags must be strong enough to withstand rough handling and be of a type which prevents loss of fines or moisture from the sample, e.g. thick polythene bags inside jute bags. The use of steel drums for large bulk samples could also be considered. Water samples in glass or plastic containers will require particular care in handling.

Undisturbed samples should be placed in wooden boxes and packed in sawdust or similar material to provide added protection. Collision between tubes in transit can easily damage sensitive samples.

2.10 Sample Reception

2.10.1 Registration. Full details of the sample, as written on the label is checked and

amended and weighed and must be entered in the laboratory register. A unique number is allocated to the sample and this number is used subsequently on all test sheets for the sample. A copy of the formalised testing programme should accompany the sample through the various stages of testing.

2.10.2 Initial treatment

a) Natural moisture content samples should be taken first, as quickly as possible. b) Air drying should be done by leaving the soil spread out in trays or on a hard, clean

floor in the laboratory for 2-3 days.

c) Oven drying must be done at the correct temperature (110±50C).

d) No attempt should be made to quarter down or riffle material which is in lumps or is larger than the size of the riffle-box chutes.

2.10.3 Storage. Storage of all samples should be in an orderly and systematic manner so that

they can be subsequently located easily. The storage facility itself should be a secure area, free from the risk of contamination or other harmful influences.

Undisturbed samples may be damaged by vibration or corrosion of tubes and should be stored with especial care. Tubes containing wet sandy or silty soils should be stored upright (suitably protected against being knocked over), to prevent possible slumping and segregation of water. The end caps of tube samples which are to be stored for long periods should be sealed with wax, in addition to the wax seal next to the sample itself. Samples which have been tested should not be disposed of without the authority of the laboratory section head.

2.11 Sample Drying

Many tests require the material to be drier at the start of the test than the sample as obtained from the field. Some means of drying the sample must, therefore, be utilised. In the case of liquid and plastic limit tests, it is essential that the material is air dried

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an oven or by other artificial means. The frequent need to dry samples quickly is more often a sign of bad planning than of an efficient laboratory.

2.11.1 Air drying. This is essential for liquid and plastic limit tests and is the preferred

procedure for all other tests.

The sample should be spread out in a thin layer on a hard clean floor or on a suitable metal sheet. Ordinary corrugated galvanised roofing sheets are perfectly satisfactory for this purpose. The material should be exposed to the sunlight and should be in a layer not more than 20 mm thick. Cohesive materials such as clays, require breaking by hand or with a rubber mallet into small pieces, to allow drying to take place without too much delay. The soil should periodically be turned over and a careful check should be made to ensure the material is removed to a sheltered place if it starts to rain. In the case of soft stone or gravels, care should be taken to ensure only lumps of cohesive fines are broken up and that the actual stone particles are not destroyed. In the case of fine-grained materials, it is generally beneficial to the later stages of testing to pass the dried particles through a No. 4 sieve.

Air drying should not normally take longer than 2 to 3 days if carried out correctly.

2.11.2 Oven drying. Oven drying should only be employed where air drying is not possible.

Oven drying will not normally have any detrimental effect on the results for sound granular materials such as sand and gravel, but may change the structure of clay soils and thus lead to incorrect test results. Oven drying must never be used in the case of liquid and plastic limit tests.

In oven drying the temperature should not exceed 1100C and the material should be dried as quickly as possible by spreading in thin layers on metal trays. Periodically, the material should be allowed to cool before testing is commenced.

2.11.3 Sand-bath drying. In certain cases an oven may not be available but the sample must

be dried quickly; sand bath drying may then be utilised.

The sand-bath consists simply of a strong metal tray or dish which is filled with clean coarse sand. The sand bath is placed on some form of heater such as a kerosene stove, a gas ring or an electric ring. The sample to be dried is placed in a heatproof dish which is embedded in the surface of the sand. A low heat should be applied so that the sand becomes heated without causing damage to the bath. The sample should be stirred and turned frequently to ensure the material at the base does not become too hot. The material should be allowed to cool before testing is commenced.

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CHAPTER 3

CLASSIFICATION TESTS

3.1 Determination of Moisture Content

3.1.1 General requirements

3.1.1.1 Scope. Water is present in most naturally occurring soils and has a profound effect in

soil behaviour. A knowledge of the moisture content is used as a guide to the classification. It is also used as a subsidiary to almost all other field and laboratory tests of soil. The oven-drying method is the definitive method of measuring the moisture contents of soils. The sand-bath method is used, where oven drying is not possible, mainly on site.

3.1.1.2 Definition. The moisture content of a soil sample is defined as the mass of water in the

sample expressed as a percentage of the dry mass, usually heating at 1050C, i.e.

moisture content, w = W D

M

M

x 100 (%)

where,

M

W= mass of water

D

M

= dry mass of sample

3.1.1.3 Sample requirements

3.1.1.3.1 Sample mass. The mass required for the test depends on the grading of the soil, as

follows;

a) Fine-grained soils*, not less than 30 grams b) Medium-grained soils*, not less than 300 grams c) Coarse-grained soils*, not less than 3 kg *Soils group

i) Fine-grained soils: Soils containing not more than 10% retained on a 2 mm test sieve.

ii) Medium-grained soils: Soils containing more than 10% retained on a 2 mm test sieve but not more than 10% retained on a 20 mm test sieve.

iii) Coarse-grained soils: Soils containing more than 10% retained on a 20 mm test sieve but not more than 10% retained on a 37.5 mm test sieve.

3.1.1.4 Accuracy of weighing. The accuracy of weighing required for test samples is as

follows;

a) Fine-grained soils: within 0.01 g. b) Medium-grained soils: within 0.1 g. c) Coarse-grained soils: within 1g.

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b) If glass weighing bottles are used they should be placed on a high shelf away from heating elements.

c) A heat-insulated pad should always be used to place hot glassware of any description.

3.1.2 Oven-drying method (standard method)

3.1.2.1 Apparatus

1) Thermostatically controlled drying oven capable of operating to 105±50C.

2) Glass weighing bottles or suitable metal containers (corrosion-resistant tins or trays).

3) Balance (to the required sensitivity). 4) Dessicator containing anhydrous silica gel. 5) Scoop, other small tools as appropriate.

Optional: Test sieves - 2 mm, 20 mm, 37.5 mm (to check classification of sample, in order to confirm required sample size).

3.1.2.2 Test procedure

a) One clean container with the lid (if fitted) is taken and the mass in grams is recorded (m1) together with container number.

Note: The container plus lid or bottle plus stopper should have the same number and be used together.

b) The sample of wet soil is crumbled and placed in the container. The container with the lid on is weighed in grams (m2).

c) The lid is removed and both lid and container are placed in the oven. The sample is then dried in a thermostatically controlled drying oven which is maintained at a temperature of 105±50C. A period of 16 to 24 hours is usually sufficient, but this varies with soil type. It will also vary if the oven contains a large number of samples or very wet samples. The soil is considered dry when the differences in successive weighings of the cooled soil at 4 hour intervals do not exceed 0.1% of the original mass.

Note. 1) For peats and soils containing organic matter a drying temperature of 600C is to be preferred to prevent oxidation of organic matter.

2) For soils containing gypsum a maximum drying temperature of 800C is preferred. The presence of gypsum can be confirmed by heating a small quantity of soil on a metal plate. Grains of gypsum will turn white within a few minutes, but most other mineral grains will remain unaltered.

d) The container is removed from the oven. For medium and coarse-grained soils, the lid should be replaced (if fitted) and the sample allowed to cool. For fine-grained soils, the container and lid, or bottle and stopper if used, should preferably be placed in a dessicator and allowed to cool. After cooling, the lids or stoppers should be replaced and the container plus dry soil weighed in grams (m3).

3.1.2.3 Calculation and expression of results

Moisture content, w=mass of moisture

mass of dry soil x 100%

= mass of container + wet soil) - (mass of container + dry soil) (mass of container + dry soil) - (mass of container) x (

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i.e. w m m m m = − − 2 3 3 1 100% x

For values up to 10% the moisture content should be expressed to two significant figures, e.g. 1.9%, 4.3%, 9.8%. For moisture contents above 10% express the result to the nearest whole number, e.g. 11%, 27%.

Note. If the moisture content is to be related to the Atterberg limits, e.g. for determining the liquidity index, and the soil contains material retained on a 425 µm sieve, the measured moisture content, w (in %), can be corrected to give the equivalent moisture content, wa (in %), of the fraction passing the 425 µm sieve, using the

equation : w w p a a =       100

where, pa is the percentage by dry mass of the portion of the soil sample passing the

425 µm test sieve.

If the particles retained on the 425 µm sieve are porous and absorb water, the amount of absorption should be determined and the value of water calculated from the equation. w w p w p p a a r a a = −  −      100 100

where; wr, is the moisture content of the fraction retained on the 425 µm test sieve. 3.1.2.4 Report. The test report shall contain the following information:

a) the method of test used; b) the moisture content;

c) the temperature at which the soil was dried, if less than 1050C; d) the comparison with Atterberg limits, if required (see Note to 3.1.2.3); e) full details of the sample origin.

The operator should sign and date test sheet. An example of the calculations made is shown in Form 3.1.1.

3.1.3 Sand-bath (subsidiary method)

3.1.3.1 Apparatus

i) Strong metal heatproof tray or dish containing clean sand to a depth of at least 25mm (sand-bath).

ii) Moisture content containers for fine soils (excluding glass containers), as used for oven drying. For coarser soils heat-resistant trays 200-250 mm square and 50-70 mm deep, the size depending on the quantity of soil required for test.

iii) Heating equipment, such as a bottled gas burner or paraffin pressure stove, or electric hot plate if mains electricity is available.

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Figure

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References

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