European Union – Brite EuRam III
A rational mix design method for
lightweight aggregate concrete using
typical UK materials
EuroLightCon
Economic Design and Construction with
Light Weight Aggregate Concrete
Document BE96-3942/R5, January 2000Project funded by the European Union under the Industrial & Materials Technologies Programme (Brite-EuRam III) Contract BRPR-CT97-0381, Project BE96-3942
The European Union – Brite EuRam III
A rational mix design method for lightweight
aggregate concrete using typical UK materials
EuroLightCon
Economic Design and Construction with
Light Weight Aggregate Concrete
Document BE96-3942/R5, January 2000
Contract BRPR-CT97-0381, Project BE96-3942
Although the project consortium does its best to ensure that any information given is accurate, no liability or responsibil-ity of any kind (including liabilresponsibil-ity for negligence) is accepted in this respect by the project consortium, the authors/editors and those who contributed to the report.
Acknowledgements
This report is a deliverable of Task 3 “Lightweight aggregate concrete production’ (activity 3.1.4.1). The report is pre-pared by Éanna Nolan, Taywood Engineering, with support from Taylor Woodrow Construction Ltd. and Lytag UK Ltd. For further information contact É. Nolan (+44) 181 575 46 34, Taywood Engineering, 345 Ruislip Road, Southall, Mid-dlesex UB1 2QX, UK or by e-mail [email protected]
Information
Information regarding the report:
Éanna Nolan, Taywood Engineering, 345 Ruislip Road, Southall, Middlesex UB1 2QX, United Kingdom Tel: +44 181 5754634, e-mail: [email protected]
Information regarding the project in general:
Jan P.G. Mijnsbergen, CUR, PO Box 420, NL-2800 AK Gouda, the Netherlands Tel: +31 182 540620, Email: [email protected]
Information on the project and the partners on the Internet: http://www.sintef.no/bygg/sement/elcon ISBN 90 376 0394 7
The European Union – Brite EuRam III
A rational mix design method for lightweight
aggregate concrete using typical UK materials
EuroLightCon
Economic Design and Construction with
Light Weight Aggregate Concrete
Document BE96-3942/R5, January 2000
Contract BRPR-CT97-0381, Project BE96-3942
Selmer ASA, NO
SINTEF, the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology, NO
NTNU, University of Technology and Science, NO ExClay International, NO
Beton Son B.V., NL B.V. VASIM, NL
CUR, Centre for Civil Engineering Research and Codes, NL Smals B.V., NL
Delft University of Technology, NL IceConsult, Línuhönnun hf., IS
The Icelandic Building Research Institute, IS Taywood Engineering Limited, GB
Lias-Franken Leichtbaustoffe GmbH & Co KG, DE Dragados y Construcciones S.A., ES
Eindhoven University of Technology, NL Spanbeton B.V., NL
Table of Contents
PREFACE
5
SUMMARY
7
1
INTRODUCTION
8
2
OBJECTIVES
9
3
PROGRAMME OF TESTS
10
3.1
A study of aggregate absorption properties
10
3.2
Paste characterisation using the flowcyl apparatus
10
3.3
Workability prediction of LWA concretes
11
4
LABORATORY PROCEDURES AND TEST METHODS
12
4.1
Pre batching and batching procedures
12
4.2
Concrete mix procedure
12
4.3
Concrete casting and curing procedures
13
4.4
Routine measurements on fresh and hardened concrete
13
4.5
‘Flowcyl’ test procedure
13
4.6
Water absorption of aggregates test procedure
14
4.7
Water absorption of aggregate from a paste test
procedure-Punkii-method
14
4.8
Aggregate Vacuum Absorption measurement test procedure
15
4.9
Aggregate Pressurised absorption test procedure
15
4.10 Uncompacted Bulk Density of aggregates test procedure
16
5
RESULTS AND DISCUSSION
17
5.1
Study of aggregate moisture gain properties
17
5.1.1 Lytag 4 - 12mm - Moisture gain
17
5.1.2 Liapor 8 : 4 - 8 mm size - Moisture gain
18
5.1.3 The influence of ‘pumpaid’ admixture on absorption into lightweight
aggregates
19
5.1.4 The influence of ‘pumpaid’ admixture on absorption from paste
into Lytag
20
5.2
Characterisation of pastes using the ‘flowcyl’ apparatus
20
5.3
Estimation of mix workability using paste and aggregate
characteristics
22
7
REFERENCES
28
8
NOMENCLATURE
29
Appendices
A
S-curve – aggregate parameter determination
30
B
S-curves for concretes investigated
32
C
28 Day compressive strength, workability and density data
38
PREFACE
The lower density and higher insulating capacity are the most obvious characteristics of Light-Weight Aggregate Concrete (LWAC) by which it distinguishes itself from ‘ordinary’ Normal Density Concrete (NDC). However, these are by no means the only characteristics, which jus-tify the increasing attention for this (construction) material. If that were the case most of the de-sign, production and execution rules would apply for LWAC as for normal weight concrete, without any amendments.
LightWeight Aggregate (LWA) and LightWeight Aggregate Concrete are not new materials. LWAC has been known since the early days of the Roman Empire: both the Colosseum and the Pantheon were partly constructed with materials that can be characterised as lightweight aggre-gate concrete (aggreaggre-gates of crushed lava, crushed brick and pumice). In the United States, over 100 World War II ships were built in LWAC, ranging in capacity from 3000 to 140000 tons and their successful performance led, at that time, to an extended use of structural LWAC in build-ings and bridges.
It is the objective of the EuroLightCon-project to develop a reliable and cost effective design and construction methodology for structural concrete with LWA. The project addresses LWA manufactured from geologic al sources (clay, pumice etc.) as well as from waste/secondary ma-terials (fly-ash etc.). The methodology shall enable the European concrete and construction in-dustry to enhance its capabilities in terms of cost-effective and environmentally friendly con-struction, combining the building of lightweight structures with the utilisation of secondary ag-gregate sources.
The major research tasks are:
Lightweight aggregates: The identification and evaluation of new and unexploited sources spe-cifically addressing the environmental issue by utilising alternative materials from waste. Fur-ther the development of more generally applicable classification and quality assurance systems for aggregates and aggregate production.
Lightweight aggregate concrete production: The development of a mix design methodology to account for all relevant materials and concrete production and use properties. This will in-clude assessment of test methods and quality assurance for production.
Lightweight aggregate concrete properties: The establishing of basic materials relations, the influence of materials characteristics on mechanical properties and durability.
Lightweight aggregate concrete structures: The development of design criteria and -rules with special emphasis on high performance structures. The identification of new areas for applic a-tion.
The project is being carried out in five technical tasks and a task for co-ordination/management and dissemination and exploitation. The objectives of all technical tasks are summarised below. Starting point of the project, the project baseline, are the results of international research work combined with the experience of the partners in the project whilst using LWAC. This subject is
dealt with in the first task.
Tasks 2-5 address the respective research tasks as mentioned above: the LWA itself, production of LWAC, properties of LWAC and LWAC structures.
Sixteen partners from six European countries, representing aggregate manufacturers and suppli-ers, contractors, consultants research organisations and universities are involved in the Eu-roLightCon-project. In addition, the project established co-operation with national clusters and European working groups on guidelines and standards to increase the benefit, dissemination and exploitation.
At the time the project is being performed, a Working Group under the international concrete association fib (the former CEB and FIP) is preparing an addendum to the CEB-FIP Model Code 1990, to make the Model Code applicable for LWAC. Basis for this work is a state-of-the-art report referring mainly to European and North-American Standards and Codes. Partners in the project are also active in the fib Working Group.
General information on the EuroLightCon-project, including links to the individual project part-ners, is available through the web site of the project: http://www.sintef.no/bygg/sement/elcon/ At the time of publication of this report, following EuroLightCon-reports have been published: R1 Definitions and International Consensus Report. April 1998
R1a LightWeight Aggregates – Datasheets. Update September 1998 R2 LWAC Material Properties State-of-the-Art. December 1998
R3 Chloride penetration into concrete with lightweight aggregates. March 1999 R4 Methods for testing fresh lightweight aggregate concrete, December 1999
R5 A rational mix design method for lightweight aggregate concrete using typical UK materi-als, January 2000
SUMMARY
This investigation examined the properties of typical UK lightweight aggregates, Liapor 8 and Lytag. The water absorption characteristics of the aggregates were examined in the 'as received' and oven dried state. Typical UK Lightweight aggregates were found to attain a moisture con-tent close to their maximum moisture capacities, under typical pumping pressures of 4.5 MPa. The addition of a proprietary pumpaid to the absorption water was found not to influence the amount of moisture absorbed by lightweight aggregates.
The Punkii- method8 of assessing the quantity of moisture absorption of aggregates from a paste was found to yield results of large variability. The results attained suggested little difference in the absorption by lightweight aggregate from a paste without and containing pumpaid.
The ‘flowcyl’ method of paste characterisation was successfully used to view the influence of pumpaid and superplasticiser dose on the flow properties of three selected water cement ratio pastes. 'Optimum' levels of superplasticiser were selected for further work on the basis of this study.
New workability prediction functions for use in the 'flowcyl' mix design method for lightweight aggregate concrete are proposed on the basis of a series of mix trials carried out. The workabil-ity of lightweight concretes was found to change more rapidly with increasing matrix overfill content compared to normal density concrete.
Lightweight aggregate concretes manufactured with Liapor 8 were found to produce concretes with a more advantageous strength / density relationship than concrete made from UK Lytag.
Keywords
Lightweight aggregate concrete, aggregate absorption, Flowcyl, mix design, workability, pumpaid
1
INTRODUCTION
Although lightweight concrete is not a new material, its design and use is not as well accepted as normal weight concrete. This is despite a range of applications in which it offers technical advantages over normal weight concrete. That lightweight concrete is not well accepted is mainly due to a higher cost of material, a lack of confidence in it’s properties, and a lack of gen-erally accepted guidelines.
This report forms part of Brite Euram ‘EuroLightCon Project’ the objective of which is to de-velop a reliable and cost effective design and construction methodology for structural concrete made with light weight aggregates. The overall objective of this project is to address this lack of confidence and provide guidelines for the use of lightweight aggregate concrete.
Task 3 of the ‘EuroLightCon’ project, of which this report forms a part, investigates lightweight aggregate concrete production. The main sub tasks are :
To develop a mix design method with particular focus on production properties, standard com-pliance requirements like density, strength, durability and costs. The method will be based on a set of characteristic properties of the constituents determined by both existing and new methods. To evaluate test methods of LWA concrete in the fresh state and develop new methods if neces-sary.
To develop a quality assurance procedure for LWA concrete production, transport, placing and compaction, especially when it is different from normal density concrete.
The mix design method described in item 1 above, is based on the Norwegian ‘S-curve’ mix design and the work described in this report fits into the development of this method for use with Lightweight aggregate concrete.
This investigation examines the properties of typical UK lightweight aggregates, characterises several concrete matrices in terms of the Norwegian ‘flowcyl’ method and examines the rela-tionship between workability and matrix content for lightweight aggregate concretes.
2
OBJECTIVES
The objectives of this sub-activity are to:
1. Assess the water absorption of typical UK lightweight aggregates, taking pumping into consideration.
2. Characterise the paste fraction of high strength concrete mixes using the ‘Flowcyl’ test.
3. Create a range of mixes to measure the workability of selected lightweight aggregate concretes.
4. To make the data generated available for inclusion in the development of a rationa l-ised mix design.
3
PROGRAMME OF TESTS
The following test programme was devised to achieve the stated objectives of sub-activity 3.1.4.1. Three main studies were planned to address the objectives.
3.1
A study of aggregate absorption properties
The variables considered are shown in table 1 below.
Table 1 - Variables in the study of lightweight aggregate absorption properties
Aggregate type
Liapor 8 : 4 - 8 mm size Lytag 4 -12 mm size (pumping grade) Moisture
condi-tion As Received moisture condition Oven Dry moisture condition Water application
method
Normal pressure absorption
Vacuum
Applic ation Pumping pressure
Water additions With pumpaid Without pumpaid
A further part of this study included an assessment of the actual absorption of water into the lightweight aggregate from a paste.
3.2
Paste characterisation using the flowcyl apparatus
Table 2 shows the variables considered in the characterisation of pastes
Table 2 - Variables for paste characterisation study
Nominal water cement
ratio of paste 0.25 0.30 0.35
Superplasticiser content
Various between 0% and 3% (fluid volume by weight of cement l/kg)
Pump-aid No pumpaid 1% pumpaid fluid volume
by weight of cement) Note : water cement ratio of the mix includes allowance for water absorption of the aggregates but not
3.3
Workability prediction of LWA concretes
Table 3 shows the variables considered in the study of workability prediction of lightweight concrete aggregate mixes.
Table 3 - Variables used in study of workability prediction of lightweight concrete mixes.
Nominal
w/c ratio of Mix 0.25 0.30 0.35
Paste content of mix
Various - chosen to give spread of workabilities
Aggregate type Liapor 8
4-8 mm size
Lytag 4 -12 mm size (pumping grade) Note : Water cement ratio of the mix includes allowance for water absorption of the aggregates but not
4
LABORATORY PROCEDURES AND TEST METHODS
4.1
Pre batching and batching procedures
1. Particle and Bulk densities of the normal weight sand and lightweight coarse aggregates were predetermined using standard test methods (BS 812 : Part 2 (1)). All sand used in this investigation was natural marine dredged sand of normal density.
2. The nominal 'as received' saturation contents of the two LWA used in this investigation were Liapor 17% moisture content and Lytag 11% moisture content unless otherwise stated. Exact determinations of moisture content were made for each concrete mix, as detailed be-low.
3. Aggregates required for the mix were put into a large pan mixer and mixed briefly. The blended aggregates were then re-bagged separately ready for use in trial mixes.
4. Moisture contents (24 hours drying in a conventional oven at 105 Degrees C) were taken from the blended constituent sand and lightweight coarse aggregates.
5. The moisture correction for the sand used in the mix was calculated by comparing the measured moisture content with the moisture content of the saturated surface dry sand (us-ing BS 812 : Part 109: method (2)). A correction to the quantity of water in the mix was then calc ulated.
6. A sample of LWA was selected and it’s 30-minute water absorption measured directly. This test was carried out on the day of mixing with the sample taken from the aggregates blended for use in the mix. The resulting water absorption (expressed as a percentage of initial weight) was assumed to represent the quantity of moisture that was absorbed into the LWA during mixing and casting. A correction to the quantity of water to be added to the mix was then calculated.
7. The final mix design with corrected water and adjusted aggregate batch weights was then adopted in accordance with the calculation shown in Appendix D.
All constituents were batched by weight (mix design was based on volume).
4.2
Concrete mix procedure
1. The air temperature of the laboratory was measured prior to each mix. 2. The mix pan and mixer blades were dampened prior to mixing.
3. The water to be added to the mix was combined with the superplasticiser prior to addition to the mix.
4. The lightweight coarse aggregate was added to the mix pan along with two thirds of the wa-ter (including superplasticiser) to be added to the mix. Afwa-ter a brief period of mixing, the pan was covered with plastic sheeting and allowed to stand for 15 minutes.
5. The required cement was then added, immediately followed by the required sand.
6. The mixture was then mixed for 60 seconds after which the rest of the water and superpla s-ticiser was added. The mix was then mixed for a further 30 seconds. The mix was then hand mixed to ensure full mixing of the constituents.
8. The mixture was finally mixed for a further 60 seconds
A conventional type, 50 Litre (Creteangle), pan mixer was used for all mixes.
4.3
Concrete casting and curing procedures
All moulds and formwork shutters were oiled prior to use and were free from dust and dirt. All compressive strength cubes were manufactured to the requirements of BS 1881 : part 108 (3). 1. Casting of standard 100 mm compressive strength cubes was carried out in two 50 mm la
y-ers. Each layer was vibrated using a vibrating table. Vibration was continued until air stopped rising to the surface of the concrete in the cube mould. Vibration of a set of cubes from the same mix was carried out at the same time to reduce inter-cube variation.
2. The specimens were given a troweled finish, moved to a controlled temperature laboratory (20 °C) and covered to stop evaporation.
3. After 24 hours the cube moulds were struck and the cubes were placed in a water tank of 20 °C ± 2 °C until testing at the age of 28 days.
4.4
Routine measurements on fresh and hardened concrete
1. Slump (BS 1881 : Part 1024) and Flowtable (BS 1881 : Part 1055) measurements were
car-ried out, where appropriate, immediately after the completion of the mix.
2. Stripping density was carried out by a simple weight measurement of compressive strength cubes both in air and water (not carried out for all mixes).
3. At the age of 28 days the compressive strength cubes were removed from the water (20 °C) and excess surface moisture removed. The weight of each cube in air and in water is taken to give a 28 day saturated density.
4. The cubes were then tested for compressive strength to the requirements of BS 1881 : Part 116 6.
4.5
‘Flowcyl’ test procedure
1. An electronic balance was set up underneath the flowcyl and attached to a datalogging de-vice. The time interval between consecutive weight measurements was set to 2 seconds. 2. The mix procedure for the cement paste was carried out in accordance with reference7.
3.
After mixing, the paste was poured into the flowcyl while the lower outlet was covered to prevent the loss of material.
4. The balance was set to zero and the data logging device switched on immediately prior to allowing the paste to flow out of the flowcyl.
5.
The weight increase on the balance with time was recorded at 2 second intervals.6. The density of the paste was measured by filling a container of known volume and finding the weight of the paste inside.
7. The results of the flowcyl test were calculated using a spreadsheet programme provided by the SINTEF, Trondheim, Norway. This programme was modified to work on the English language version of Excel. Inputs required for this programme are :
• The list of weight measurements recorded by the data logger device. • The density of the paste under test.
8. After inputting these values the graph of the highlighted data were drawn and a 2nd order polynomial was fitted to the differential data. The a, b and c parameters from the equation of this line were back inputted into the program.
9. The value of λq was then calculated and recorded.
4.6
Water absorption of aggregates test procedure
1. A sample of aggregate of known moisture condition (‘As received’ or ‘Oven dried’) was selected and weighed (W1)
2. The aggregate was then immersed in the liquid under test. 3. The aggregate was removed after a determined period of time.
4. The saturated surface dry (SSD) condition of the aggregate sample was obtained by remov-ing surface water from the aggregate usremov-ing ‘blottremov-ing type’ paper. Aggregate residue was ex-tracted from the water and paper by means of oven drying and weighed (Wr).
5. The SSD weight of the aggregate (plus any aggregate residue weight, Wr) was obtained (W2).
6. The percentage absorption (Abs) of the aggregate was determined by Equation 1.
Abs = (W2-W1)/W1 (1)
4.7
Water absorption of aggregate from a paste test
procedure-Punkii-method
(8)1. Fifteen individual aggregate particles of known moisture content were selected for each absorption test. The initial moisture content was recorded (MC).
2. The appropriate mortar paste (of known w/c ratio) was mixed and placed in 3 containers. 3. aggregate particles were pressed into the paste in each container and left for the required
period of absorption.
4. After the absorption period the aggregate particles were removed and the excess paste was removed using a small brush (normally used for cleaning test sieves).
5. The aggregate particles were then individually weighed on a balance accurate to four deci-mal places of a gram and the data was recorded. (Wa1 to Wa5)
6. The aggregate was then oven dried over a 48 hour period at a temperature of 105 °C. 7. Finally the aggregate particles were re-weighed and the weights recorded. (Wb1 to Wb5). 8. The aggregate absorption values were calculated using equation 28
(
)
Wabs
M
M
M
Wcr
MC
=
−
+
−
+
−
−
2
3
3
1
ω
1
ξ
ξ
(2) WhereWabs % water absorption into aggregate particles. M2 sum (Wa1 to Wa5)
ξ ratio between chemically combined water and cement (0.0258). Wcr effective water cement ratio of the mortar.
The following procedure was used to estimate the quantity of paste that adhered to the aggregate after the absorption period.
1 Average dried paste content on aggregate surface = ω=
[Sum (Wo1 to Wo5) - Sum (Wf1 to Wf5)] / Sum (Wf1 to Wf5).
2 Saturated surface dry aggregates were initially weighed on a balance of appropriate accu-racy.(Wo1 to Wo5)
3 The aggregate particles were placed in the design paste.
4 The aggregate was removed and the paste was removed from each particle using a small brush (normally used for cleaning test sieves) in exactly the same manner as above.
5 The aggregate particles were then re-weighed and the readings recorded.(Wf1 to Wf5).
4.8
Aggregate Vacuum Absorption measurement test
procedure
1. A sample of aggregate of known moisture condition (‘As received’ or ‘Oven dried’) was selected and weighed (W1).
2. The aggregate was placed in a vacuum jar and the vacuum applied.
3. After a period of 5 minutes vacuum application, fluid (using de-ionised water) was intro-duced into the vacuum flask without degrading the vacuum.
4. The aggregate was kept in water for a further 30 minutes while the vacuum was running. After this period the aggregate was removed.
5. The Saturated surface dry (SSD) condition of the aggregate sample was obtained by remov-ing surface water from the aggregate usremov-ing ‘blottremov-ing type’ paper.
6. The SSD weight of the aggregate was obtained (W2).
7. The percentage absorption under vacuum (Abs) of the aggregate was determined by Equa-tion 3.
Abs = 100 *(W2-W1)/W1 (3)
4.9
Aggregate Pressurised absorption test procedure
1. A sample of aggregate of known moisture condition (As received / Oven dried ) was se-lected and weighed (W1).
2. The aggregate was placed in pressure vessel and a quantity of water sufficient to cover the aggregate was introduced.
3. The pressure vessel was sealed (this operation took 5 minutes) and a pressure of 4.5 MPa (≈ 45 Bar or ≈ 652.5 psi) (Typical pumping pressure) was applied by means of nitrogen gas. 4. After a stated period of time, the pressure was released and the test sample was removed
from the pressure vessel.
5. The Saturated surface dry (SSD) condition of the aggregate sample was obtained by remov-ing surface water from the aggregate usremov-ing ‘blottremov-ing type’ paper.
6. The SSD weight of the aggregate was recorded (W2).
Abs = 100 *(W2-W1)/W1 (4)
4.10 Uncompacted Bulk Density of aggregates test procedure
1. A sturdy metal container was weighed empty (W1).
2. The container was then filled with water (@ 20 °C and weighed (Ww)).
3. After emptying the water and drying the container fully it was then filled with the aggregate (in the ‘as received’ state) and levelled off with a straight edge. The weight of the container was then recorded as (W2).
4. The volume of the container was determined by Equation 5.
Volume (V) = (Ww-W1)/1000 (5)
5. The bulk density of the aggregate was determined using Equation 6
5
Results and discussion
5.1
Study of aggregate moisture gain properties
5.1.1 Lytag 4 - 12mm - Moisture gain
The results of the aggregate moisture gain tests for Lytag 4-12 mm and Liapor 8 : 4 - 8 mm size are shown in figures 1 and 2 respectively.
Atmospheric absorption of the aggregates was intended to give an indication of water absorp-tion by aggregates in the mixing procedure. It is recognised that aggregates in a moist paste do not absorb as much moisture as from water. Use of moisture absorption from water gives a comparative measure of absorption rather than an absolute measure.
The application of 4.5MPa (≈ 45 Bar ≈ 650 psi) of pressure was intended to represent the mag-nitude of the force applied to the concrete by pumping to a height of 100m9.
The vacuum application was used to saturate the aggregate samples as fully as possible. This method is commonly used to saturate porous specimens, most commonly concretes.
Figure 1 - Lytag 4 -12 mm size - Aggregate absorption properties
The ‘as received’ moisture content referred to in figure 1 was measured as 11.4 % for the Lytag sample tested. This value was taken to be representative of the normal UK Lytag production moisture content. Lytag UK representatives10 have indicated that the moisture content of
pro-duction is presently approximately 10%.
Figure 1 shows the results of atmospheric absorption tests on the Lytag aggregate up to a period of 24 hours. The difference between the moisture intake of ‘as received’ and oven dried aggre-gate is as expected, with the drier material gaining more weight.
Lytag 4 - 16 mm pumping grade
0.00 5.00 10.00 15.00 20.00 25.00 30.00 0 200 400 600 800 1000 1200 1400 1600 Time (mins)
Weight Gain (% w.r.t initial wgt)
Oven Dried - Vacuum Saturated
Oven Dried - 4.5 MPa Pressure
Oven Dried - Atmospheric Absorption
As Received - 4.5 MPa Pressure
As Received - Vacuum Saturated
Assessing the results as a whole it can be seen that the weight gain due to vacuum saturation of the ‘as received’ aggregate is lower than might have been expected (The relationships between weight gain in oven dried and ‘as received’ aggregates are similar for atmospheric absorption and pressure application). This indicates that the ‘as received’ moisture in the Lytag aggregate pores may have disrupted the vacuum saturation process.
The vacuum saturation of the oven dried aggregate indicates that the total moisture capacity of Lytag 4 -12 mm is of the order of 25% of the oven dried weight.
The application of water at a pressure of 4.5 MPa to the ‘as received’ Lytag was found to intro-duce more moisture into the material than either vacuum saturation or atmospheric absorption. This highlights the fact that a pumped concrete containing Lytag could expect to loose signif i-cant quantities of moisture from the paste into the aggregate. If the increase in moisture caused by the application of pressure is combined with the initial moisture content of the Lytag then the resulting moisture content of the Lytag approaches the total moisture capacity of the aggregate. This is further reflected by the 22% moisture gain by oven dried Lytag subjected to the applic a-tion of water at 4.5 MPa pressure.
5.1.2 Liapor 8 : 4 - 8 mm size - Moisture gain
Figure 2 shows the results of a similar set of weight gain tests carried out on Liapor 8 : 4 - 8 mm size aggregate. The measured ‘as received’ moisture content was 17.1%.
As with Lytag, the vacuum saturation of the ‘as received’ Liapor aggregate was not successful with minimal weight gain due to vacuum saturation. The oven dried vacuum saturation indi-cates that Liapor 8 has a moisture capacity of approximately 22%.
Figure 2 - Liapor 8 : 4 -8 mm size - Aggregate absorption properties
The ‘as received’ Liapor 8 material contained a lot of moisture and therefore did not have a large atmospheric absorption. The oven dried atmospheric absorption was much larger and
ex-Liapor 8 : 4 - 8 mm size 0.00 5.00 10.00 15.00 20.00 25.00 30.00 0 200 400 600 800 1000 1200 1400 1600 Time (mins)
Weight Gain (% w.r.t initial wgt) As Received - 4.5 MPa Pressure
As Received - Atmospheric Absorption As Received - Vacuum Saturated
Oven Dried - Atmospheric Absorption
Oven Dried - 4.5 MPa Pressure
hibited a continued absorption after 24 hours.
As discussed above, the vacuum saturation of ‘as received’ aggregate was seen not to be suc-cessful, with an extremely low moisture gain being evident.
The application of pressure to ‘as received’ Liapor 8 caused a significant moisture gain (≈ 6%). Again, when the initial moisture content of 17.1% is taken into consideration this means that the Liapor aggregates could expect to be substantially saturated when subject to the types of pres-sures associated with pumping.
Comparatively, Liapor 8 was shown to have a lower total moisture capacity than Lytag.
5.1.3 The influence of ‘pumpaid’ admixture on absorption into
lightweight aggregates
Figure 3 shows the results of a study that was intended to study the influence of a pumpaid on the atmospheric absorption of moisture into aggregates. A standard mix dose (1% liquid vol-ume by weight of cement - for a 0.3 w/c ratio mix) of pumpaid admixture was introduced into the water used for absorption and 24 hour absorption tests were carried out. As can be seen, no significant difference in absorption profiles can be identified either in the case of Lytag or Lia-por 8. Further investigation of the admixture indicated that it may only become active when in an alkaline environment, however absorption tests which used alkaline water (pH 11.1) and pumpaid admixture for absorption showed no reduction in absorption when compared to absorp-tion from water alone.
Figure 3 - Influence of pumpaid on the absorption of lightweight aggregates
The results in figure 3 can not be taken as proof that the addition of pumpaid to a mix will not influence the quantity of moisture absorbed by lightweight aggregates from a concrete mix. The results do indicate that there is no easy way of measuring any influence that the addition of a pumpaid may have on lightweight aggregate moisture gain in a concrete mix. The problem was further investigated in an additional series of tests described in section 5.1.4.
5.1.4 The influence of ‘pumpaid’ admixture on absorption from paste
into Lytag
An investigation into Lytag absorption of moisture from paste was undertaken to further assess the influence of pumpaid on lightweight aggregate absorption. Figure 4 shows the results of this study. The method used to measure the absorption from paste is described in section 4.7. There is no readily identifiable trend between absorption from paste containing pumpaid and paste not containing pumpaid. One negative result suggests that ‘as received’ Lytag lost water to the paste. It is much more likely that this result illustrates a large variability associated with the method used rather than describing a real phenomenon. The results suggest that there is no large difference in absorption from paste with and without pumpaid although it is acknowledged that a large variability is present in the results obtained.
Figure 4 - Water absorption from paste with and without pumpaid admixture
5.2
Characterisation of pastes using the ‘flowcyl’ apparatus
Figure 5 shows the full results of the paste characterisation study. The flowcyl Lambda Q (λq) is a measure of the ability of the paste to flow through a standard flowcone 7, 11. The lower the
value of λq the more fluid the paste and a λq = 1 denotes a paste with no flow. In gene ral the three pastes investigated had low w/c ratios and were found to be reasonably stiff.
The lower w/c ratio pastes were seen to have higher λq values and therefore were more viscous. The higher 0.35 w/c ratio paste can be seen to have lower λq values and flowed more freely through the standard cone.
The superplasticiser (a melamine based product) content is a fluid weight expressed as a per-centage of the cement content. The solids content of the superplasticiser is 38% and this has not been included in the nominal w/c ratio, see table 4. Fines <0.125 mm were included in each
paste in proportion to their quantity in a full scale mix containing 60% coarse lightweight ag-gregate and 40% normal density sand.
‘Optimum’ S/P for use with pupaid shown
in each case
Figure 5 - Flowcyl Lambda values versus superplasticiser content for 3 selected pastes
As the quantity of superplasticiser (38% solids content) in each of the pastes increased, the flu-idity of the paste increased until it reached a ‘plateau’ level. The addition of more superplasti-ciser in excess of the ‘plateau’ level had a much reduced effect. This ‘plateau’ level of super-plasticiser addition was judged to denote an 'optimum' supersuper-plasticiser content. The higher w/c ratio paste had a clearly defined 'optimum' level whereas choosing an 'optimum' level for the 0.25 w/c ratio paste was more subjective. Table 4 shows the 'optimum' levels of superplasticer content chosen from figure 5.
Table 4 - 'Optimum' superplasticiser contents (based on figure 5)
Nominal water cement ratio (w/c)* 0.25 0.30 0.35 'Optimum' Superplasticiser content
(%)** 3.0 2.5 1.5
'Optimum' superplasticiser content
used with pumpaid (%)** 2.25 1.5 1.0
* Nominal water cement ratio. See table 5.
** fluid volume expressed as a percentage of the cement content
The addition of a standard dose of 1% fluid volume by weight of cement of pumpaid admixture (2.5% solids content) was added to each of the cement pastes. The pumpaid admixture is de-signed to make a concrete more cohesive and therefore less prone to segregation during
pump-ing. After pumping, the concrete is reworked for a short period until the concrete returns to its original condition. Therefore, the amount of mixing is critical as too much mixing would work out the influence of the admixture. A constant period of 60 seconds mixing after the addition of the pumpaid was adopted and used for all mixes in this study.
The influence of the pumpaid on the fluidity of paste can be seen from figure 5. The solid lines represent the paste flow characteristics without pumpaid or when the influence of pumpaid has been worked out. The dashed lines represent the paste flow characteristics with the pumpaid 'active'. The pumpaid can be seen to make the concrete less fluid over a range of superplasti-ciser contents for each paste. The increase in workability in pastes containing pumpaid occurs over a smaller range of superplasticiser contents than in ordinary pastes. Experimental observa-tion indicated that for each of the three pastes investigated, an increased superplasticiser content resulted in a reduced time taken to mix out the influence of pumpaid. Where values of paste including pumpaid are similar to those without pumpaid, the influence of the pumpaid has been worked out by the 60 second standard ‘post pumpaid’ mixing time.
The most effective dose of superplasticiser for use with the stated dose pumpaid is estimated as the largest difference between the λq values for pastes with and without pumpaid (shown in ta-ble 4). In reality dosing trials on-site are likely to produce a more practical estimate of an 'opti-mum' dose / time of addition etc.
The ''Optimum'' doses of superplasticiser for use with superplasticiser and pumpaid (from table 4) were adopted for all concrete mixes manufactured in this investigation. As admixture doses were based on the weight of cement in each mix and fixed to a 'optimum' dose for each nominal water cement ratio, actual free water cement ratios can be calculated. This resulted in the desig-nated nominal water cement ratios having actual water cement ratios as detailed in table 5.
Table 5 - Nominal and Actual w/c ratios for pastes and concretes
Nominal water cement ratio (w/c) 0.25 0.30 0.35 Actual w/c ratio with mixes including
superplasticiser 0.264 0.309 0.356
Actual w/c ratio with mixes including
superplasticiser and pumpaid 0.274 0.319 0.366
Water cement ratios quoted in this report are nominal water cement ratios unless otherwise stated.
5.3
Estimation of mix workability using paste and aggregate
characteristics
The full set of slump, flow, density and 28 day compressive strength data for 0.25, 0.3 and 0.35 nominal w/c ratio concretes made with both Lytag and Liapor 8 aggregates is given in Appendix B. Figures 6 and 7 show the results of slump and flow measurements for 0.3 nominal w/c ratio concrete mixes made with Lytag and Liapor 8 lightweight aggregates respectively.
Figure 6 - Workability measurements for 0.3 w/c ratio concrete using Lytag aggregate
Both slump and flow increase with increasing matrix content as expected. The minimum flow was arbitrarily taken as 300 mm as readings below this value have little meaning since the con-crete tends to slump not flow.
Liapor 8 : 4 -8 mm - 0.30 w/c ratio 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 2 0 22 24 26 28 3 0 32 34 36 38 4 0 F p = Volume % matrix Kp
= Slump and Spread (cm)
Slump K p _ S l Kt_Sl Spread K p _ S p Kt_Sp
Figure 7 - Workability measurements for 0.3 w/c ratio concrete using Liapor 8 aggregate
The Mørtsell method of predicting slump and flow 7, 11 (using the s-curve functions) has been
shown to work for normal weight concretes. Using data (partly from this investigation) the functions are due to be updated for use with lightweight concrete.
Several parameters must be calculated prior to using the S-curve workability prediction method,
Lytag 4 - 12 mm - 0.30 w/c
0 10 20 30 40 50 60 70 20 25 3 0 35 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp
namely the flow resistance of the paste (λq) and various aggregate factors combined into the term (Hm). Full details of the aggregate test results and the calculation of Hm are presented in Appendix A.
The original functions proposed by Mørtsell 7, 11 to describe the change of slump and flow with change in matrix content were found not to predict the workability of lightweight aggregate concretes. Therefore the function was modified to fit the lightweight data.
Mørtsell’s method of predicting slump includes the sub function, α - slump (Equation 7), and α - spread (Equation 8) which influences the rate at which the concrete workability changes from minimum to maximum with changing matrix content.
α - slump = 115 * EXP (-4.45 * λq) (7)
α - spread = 115 * EXP (-4.45 * λq) (8)
By changing the functions to
α - slump(mod) = 115 * EXP (-2.225 * λq) (9)
α - spread(mod) = 115 * EXP (-2.225 * λq) (10)
It was found that the modified prediction functions generally fitted the data obtained from lightweight aggregate concrete (shown in figures 6 and 7 and Appendix B). This function is only a first approximation of the lightweight aggregate concrete s-curve, more extensive data is required. The modified prediction functions (equations 9 and 10) have been used in all the ma-trix-slump graphs in this report and appendices unless otherwise stated.
The difference between the original and modified s-curve functions can be assessed by compar-ing two slump s-curve functions graphically (figure 8).
Figure 8 - Comparison of normal weight concrete and modified ‘lightweight’ Slump S-curve prediction functions
It is evident that the change of slump with change in matrix content of a mix is much more abrupt in LWA concrete than in NDC. The aggregate density, therefore has a large influence on the change in slump with matrix content.
0 5 10 15 20 25 30 10 20 30 40 50 60 70 Matrix Content (%) Lytag 0.3 w/c - modified slump prediction function Mφrtsell dense aggregate slump prediction function - Lytag 0.3 w/c
The increase in workability with increasing matrix content may be considered as the interaction between the aggregate and matrix components of the fresh concrete mix. A matrix dominated system being full slump and aggregate dominated system being zero slump.
This investigation has highlighted that in lightweight concrete the change from aggregate to ma-trix domination of the slump with increase in mama-trix content is rapid compared to NDC. This could well be due to the increased ability of the matrix phase to overcome inertia and cause ‘catastrophic’ movement of less dense aggregates. Figure 8 suggests that the start of slump oc-curs at a larger matrix content in LWAC.
This may be due to the cohesive properties that the matrix imparts acting more significantly on lighter aggregates, however there is little experimental evidence produced by this investigation to either refute or support this hypothesis.
A full set of 28 day compressive strength and density measurements for the mixes produced in this investigation are presented in Appendix C.
Figures 9 and 10 show strength / density relationships for Lytag and Liapor 8 aggregates. The Liapor 8 aggregates displayed a more advantageous strength density relationship, especially when used with an initially lower moisture state (as highlighted for 4 mixes in figure 10). Examining the mix recipe data for these 4 mixes in Appendix D it can be seen that although a substantially lower moisture content of existed in the Liapor aggregate the absorption properties were not significantly different. This may have been caused by a moisture distribution through the aggregate as shown in figure 11.
It should be noted that the Lytag aggregate used in this investigation is that which is supplied for use on the UK market and is known to be different from that available on continental Europe.
Maximum strengths achieved for these aggregates are not maximum possible values as the use of silica fume and different aggregate/sand ratios are known to produce concrete compressive strengths in excess of the values shown in figures 8 and 913.
Figure 9 – Lytag Strength Density relationship for project mixes
1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 50 55 60 65 70 7 5 8 0
Compressive Strength (MPa)
Saturated 28 day Density (Kg/ Cu.m)
Strength / Density Trend line Initial aggregate moisture content approx. 8%
Figure 10 - Liapor 8 Strength Density relationship for project mixes
Similar absorption values for both aggregates
Moisture (10%) held in Moisture (20%) distributed throughout
outermost part of aggregate the aggregate.
Figure 11 - Moisture distribution in Liapor Aggregate
Dry core 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 50 55 60 65 70 75 80
Compressive Strength (MPa)
Saturated 28 day Density (Kg/ Cu.m)
Initial aggregate moisture content approx. 10%
Strength / Density Trend line
6
CONCLUSIONS
The following specific conclusions have been drawn from the experimental studies de-tailed in this report.
1. Typical UK Lightweight aggregates were found to attain a moisture content close to their maximum moisture capacities, under typical pumping pressures (4.5 MPa). 2. The addition of a pumpaid to absorption water did not influence the amount of
mois-ture absorbed by lightweight aggregates. This suggests that the use of a pumpaid could not be expected to influence the amount of absorption into lightweight aggre-gates in pumped concrete.
3. The Punkii- method8 of assessing the quantity of moisture absorption of aggregates was assessed as yielding results of large variability. The results attained suggested little difference in the absorption by lightweight aggregate from a paste without and containing pumpaid.
4. The ‘flowcyl’ method of paste characterisation was successfully used to view the in-fluence of pumpaid and superplasticiser dose on the paste flow properties. 'Optimum' levels of superplasticiser were selected for further work on the basis of this study. 5. The workability prediction functions developed by Mørtsell for normal weight
con-crete were found not to be applicable to lightweight concon-crete. The workability of lightweight concretes was found to change more rapidly with matrix content when compared to normal weight aggregate concrete.
6. Modified functions for the prediction of workability of lightweight concrete are pro-posed.
7. Liapor 8 produced concretes with a more advantageous strength / density relationship than concrete made from UK Lytag.
7
REFERENCES
(1) BS812: Part 2 (1975) ‘Aggregates - Methods of determination of physical prop-erties’ British Standards Institution, London.
(2) BS 812: Part 109 (1990) ‘Methods for determination moisture content’, British Standards Institution, London.
(3) BS 1881: part 108 (1983) ‘Method of making test cubes from fresh concrete.’ British Standards Institution, London.
(4) BS 1881: Part 102 (1983) ‘Method of determination of slump’ British Standards Institution, London.
(5) BS 1881: Part 105 (1984) ‘Method of determination of flow’ British Standards Institution, London.
(6) BS 1881: Part 116 (1983) ‘Method of determination of compressive strength of concrete cubes’ British Standards Institution, London.
(7) Ernst Mørtsell, Sverre Smeplass, Tor Arne Hammer, Magne Maage ‘Flowcyl - How to determine the flow properties of the matrix phase of high performance concrete’ Proc 4th International Symposium on utilisation of High Strength / High Performance con-crete, 29 - 31 May 1996, Paris . Vol. 2. pp 261 - 268.
(8) Jouni Punkki, Odd E. Gjorv “Water absorption by high-strength lightweight aggregate”, Proc. High Strength Concrete 1993, 20 - 24 June, Lillehammer, Norway. pp 713 - 721.
(9) Personal communication with Mr. Andrew Turner, Putzmeister Ltd. (UK)
(10) Personal communication with Mr. Tim Cleverley, Lytag UK. June 17th, 1998.
(11) Ernst Mørtsell ‘Modellering AV Delmaterialenes betydningfor Betongens kon-sistens’ PhD Thesis. 1996. Institutt for Konstruksjonsteknikk, Trondheim, Norway. pp 301.
(12) BS 812 : Section 103.1: (1985) ‘Aggregate - Sieve Tests’, British Standards Institution, London.
(13) Nigg Gravity Base Project – Mix development trials carried out by Taywood Engineering Ltd. for Taylor Woodrow Construction. 1998.
8
NOMENCLATURE
LWA Lightweight aggregate
LWAC Lightweight aggregate concrete NDA Normal density aggregate NDC Normal density concrete w/b water binder ratio w/c water cement ratio
CEB Comité Euro-international du Béton CEN Comité Européen de Normalisation CTR Cost Time Resources (form) EN European Standard
FIB Féderation Internationale du Béton
FIP Féderation Internationale de la Précontrainte MG Management Group
TC Technical Committee (CEN) TG Task Group
APPENDIX A
S-CURVE - AGGREGATE PARAMETER DETERMINATION
Stock sand 130367- Tilcon 7 Oaks Quarry
Sieve size Wgt. Retain (g) % Retain % Retain Cum.%
10 0 0 0.0 0.0 0.0 6.13 2.2 0.17 5 7.1 0.55 0.7 0.7 0.7 2.36 119.1 9.29 9.3 10.0 10.0 1.18 113.2 8.83 8.8 18.8 18.8 0.6 178 13.88 13.9 32.7 32.7 0.3 578.6 45.12 45.1 77.8 77.8 0.15 236.9 18.47 0.125 24.9 1.94 20.4 98.3 49.1 < 0.125 22.5 1.75 1.8 Total 1282.5 100 189.3
Fineness Mod*. = 1.89255 150 ,300 ,600 ,1.18 mm, 2.36mm, 5.0mm sieves *Modified to use 0.125 mm sieve instead of 0.150 mm sieve
Lytag Sample No. 130336
Sieve size Initial Wgt (g) Final Wgt (g)Wgt. Retain (g) % Retain % Retain Cum.%
10 438.8 738.6 299.8 34.4 34.4 34.4 34.4 6.13 471.1 1005.8 534.7 61.4 5 488.3 579.5 7.1 0.8 62.2 96.7 96.7 2.36 429.3 454.4 25.1 2.9 2.9 99.5 99.5 1.18 406 406.2 0.2 0.0 0.0 99.6 99.6 0.6 347 347.6 0.6 0.1 0.1 99.6 99.6 0.3 322.5 324.8 2.3 0.3 0.3 99.9 99.9 0.15 299.4 299.9 0.5 0.1 0.125 271.1 271.3 0.2 0.0 0.1 100.0 50.0 < 0.125 270.1 270.3 0.2 0.0 0.0 870.7 100.0 100.0 579.7 Fineness Mod*. = 5.80
*Modified to use 0.125 mm sieve instead of 0.150 mm sieve
Liapore Sample No. 130348
Sieve size Initial Wgt (g) Final Wgt (g)Wgt. Retain (g) % Retain % Retain Cum.%
10 438.8 438.8 0.0 0.0 0.0 0.0 0.0 6.13 471.2 620.3 149.1 49.7 5 488.4 871 7.1 2.4 52.0 52.0 52.0 2.36 429.2 572.9 143.7 47.9 47.9 99.9 99.9 1.18 406 406 0.0 0.0 0.0 99.9 99.9 0.6 346.8 346.8 0.0 0.0 0.0 99.9 99.9 0.3 322.6 322.7 0.1 0.0 0.0 99.9 99.9 0.15 299.4 299.6 0.2 0.1 0.125 271.4 271.4 0.0 0.0 0.1 100.0 50.0 < 0.125 270.3 270.3 0.0 0.0 0.0 300.2 100.0 100.0 551.7 501.7 Fineness Mod*. = 5.02
Measured Particle Density (Saturated Surface Dry)
Sand 2.5744 (2574 Kg/cu.m)
Lytag 4 -12 mm 1.6827 (1683 Kg/cu.m)
Liapor 8 : 4 - 8 mm 1.7377 (1738 Kg/cu.m)
Measured Uncompacted Bulk density
Sand 1412.88 (Kg/Cu.m) Moisture content = 4.0%
Lytag 4 -12 mm 887.69 (Kg/Cu.m) Moisture content = 11.4%
Liapor 8 : 4 - 8 mm 984.47 (Kg/Cu.m) Moisture content = 17.1% All materials tested as recieved
Calculation of Hs Values for S-Curves
Aggregate Type Lytag 4 - 12 mm Aggregate Type Liapor 8 : 4- 8 mm
Volume of Sand (Vs) 0.4 Volume of Sand (Vs) 0.4
Volume of Agg (Va) 0.6 Volume of Agg (Va) 0.6
Air Voids Ratio Sand (Hs) 0.4512 Air Voids Ratio Sand (Hs) 0.4512 Air Volids Ratio Agg (Hp) 0.4725 Air Voids Ratio Agg (Hp) 0.4335 Fineness Modulus Sand (Fms) 1.89 Fineness Modulus Sand (Fms) 1.89 Fineness Modulus Agg (Fmp) 5.8 Fineness Modulus Agg (Fmp) 5.02 Agg Parameter Sand (Ts) 9 Agg Parameter Sand (Ts) 9 Agg Parameter Agg (Tp) 8 Agg Parameter Agg (Tp) 8
APPENDIX B
S-CURVES FOR CONCRETES INVESTIGATED
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 3
1 λQ = 0.92 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 2.25 % 3 m -Slump =0.00 7 Oaks Sand' - Sample No. 130367
4 n-Slump = 28.40 Liapor Aggregate - Sample No. 130348 5 m -Spread =30.00 Class 42.5 Portland Cement - Stock No 130377 6 n -Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 14.85 Trial Matrix (Fp ) Slump Spread 28 day Strength 28 Day Density
8 β-Slump = -0.40 Mix No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 14.85 15 30 23 45.5 75 2025 10 β-Spread = -0.39 18 35 27.5 60.7 73.5 2010 11 Fpn-Sl i % = 33.51 33 28 20 40 77.5 2025 12 Fpn-Sp i % = 34.11 40 26 1.5 30 72 1945 13 Fpm-Sl i % = 26.77 41 27 1 30 73.5 1950 14 Fpm-Sp i % = 27.37
Liapor 8 : 4 -8 mm - 0.25 w/c
0 10 20 30 40 50 60 70 20 25 30 35 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp 40 40 41 41 15 33 15 33 18 18
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 3
1 λQ = 0.77 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 1.5 % 3 m -Slump =0.00 7 Oaks Sand' - Sample No. 130367
4 n-Slump =28.40 Liapor Aggregate - Sample No. 130348 5 m -Spread =30.00 Class 42.5 Portland Cement - Stock No 130377 6 n-Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 20.73 Trial Mix Matrix (Fp ) Slump Spread 28 Day Strength 28 Day Density
8 β-Slump = -0.42 No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 20.73 16 30 23 52 65 1985 10 β-Spread = -0.40 19 25 0.5 30 68 2000 11 Fpn-Sl i % = 31.59 34 28 18 42.5 69 2000 12 Fpn-Sp i % = 32.19 32 29 23 53 68 1995 13 Fpm-Sl i % = 26.77 42 27 11.5 43 68.5 1950 14 Fpm-Sp i % = 27.37
Liapor 8 : 4 -8 mm - 0.30 w/c ratio
0 10 20 30 40 50 60 70 20 22 24 26 28 30 32 34 36 38 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp 19 34 34 32 32 16 16 42 42 19
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 31 λQ = 0.61 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 1.5 % 3 m -Slump =0.00 7 Oaks Sand' - Sample No. 130367/130386
4 n -Slump = 28.40 Liapor Aggregate - Sample No.'s 130348 5 m -Spread =30.00 Class 42.5 Portland Cement - Stock No 130377 6 n -Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 29.60 Trial Mix Matrix (Fp ) Slump Spread 28 Day Strength 28 Day Density
8 β-Slump = -0.43 No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 29.60 17 30 16 42 60.5 1985 10 β-Spread = -0.42 20 25 1 30 61.5 1975 11 Fpn-Sl i % = 30.15 31 28 8 37 68 2005 12 Fpn-Sp i % = 30.75 39 31 23.5 65 63 1950 13 Fpm-Sl i % = 26.77 14 Fpm-Sp i % = 27.37
Liapor 8 : 4 - 8 mm - 0.35 w/c
0 10 20 30 40 50 60 70 20 22 24 26 28 30 32 34 36 38 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp 20 20 31 31 17 17 39 39
20 20 20 31 17 17 39 39 31
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 3
1 λQ = 0.92 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 2.25 % 3 m -Slump =0.00 7 Oaks Sand' - Sample No. 130367
4 n -Slump =28.40 Lytag Aggregate - Sample No. 130336
5 m -Spread =30.00 Class 42.5 Portland Cement - Stock No 130377 6 n -Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 14.85 Trial Mix Matrix (Fp ) Slump Spread 28 Day Strength 28 Day Density
8 β-Slump = -0.40 No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 14.85 10 30 10 32 64.5 2015 10 β-Spread = -0.39 13 35 8 35 64.5 2005 11 Fpn-Sl i % = 33.51 36 32 21 58 57 2015 12 Fpn-Sp i % = 34.11 35 28 4 30 59 1995 13 Fpm-Sl i % = 26.77 43 35 28.4 63 62 2015 14 Fpm-Sp i % = 27.37
P3054År20AIII
0 10 20 30 40 50 60 70 20 25 30 35 40 45 50 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp
Lytag 4 -12 mm - 0.25 w/c
0 10 20 30 40 50 60 70 20 22 24 26 28 30 32 34 36 38 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp Erroneous Result Erroneous Result 35 10 10 36 36 13 13 35 43 43
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 3
1 λQ = 0.77 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 1.5 % 3 m -Slump = 0.00 7 Oaks Sand' - Sample No. 130367
4 n -Slump = 28.40 Lytag Aggregate - Sample No. 130336
5 m-Spread = 30.00 Class 42.5 Portland Cement - Stock No 130377 6 n -Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 20.73 Trial Mix Matrix (Fp ) Slump Spread 28 day Strength 28 Day Density
8 β-Slump = -0.42 No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 20.73 8 30 24.5 56.3 54.5 1955 10 β-Spread = -0.40 26 32 26 62.5 57.5 1970 11 Fpn-Sl i % = 31.59 25 28 10 34.5 60 1975 12 Fpn-Sp i % = 32.19 27 26 5 30 57 1960 13 Fpm-Sl i % = 26.77 28 29 18 45.5 61 1995 14 Fpm-Sp i % = 27.37 29 24 2.5 30 58.5 1965
Lytag 4 - 12 mm - 0.30 w/c
0 10 20 30 40 50 60 70 20 22 24 26 28 30 32 34 36 38 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp 26 27 27 25 25 28 28 8 8 26
LWA concrete - workability prediction graph
Taywood Engineering Ltd. - Eurolightcon Project - Task 3
1 λQ = 0.61 Mix Constituents :
2 Hm = 8.65 Superplasticiser (Sample No. 130263) Content (%) = 1.0 % 3 m -Slump =0.00 7 Oaks Sand' - Sample No. 130367
4 n-Slump = 28.40 Lytag Aggregate - Sample No. 130336
5 m -Spread =30.00 Class 42.5 Portland Cement - Stock No 130377 6 n -Spread = 70.00 Slump prediction function =115*EXP(-2.225*lQ)
7 α-Slump = 29.60 Trial Mix Matrix (Fp ) Slump Spread 28 day Strength 28 Day Density
8 β-Slump = -0.43 No. (volume %) (cm) (cm) (MPa) (Kg/cu.m)
9 α-Spread = 29.60 11 30 12.5 39 51.5 1940 10 β-Spread = -0.42 14 25 0.5 30 52 1945 11 Fpn-Sl i % = 30.15 37 32 20.5 37 51.5 1940 12 Fpn-Sp i % = 30.75 38 29 15 36 51.5 1950 13 Fpm-Sl i % = 26.77 14 Fpm-Sp i % = 27.37
Lytag 4 -12 mm - 0.35 w/c
0 10 20 30 40 50 60 70 20 22 24 26 28 30 32 34 36 38 40 Fp = Volume % matrix Kp= Slump and Spread (cm)
Slump Kp_Sl Kt_Sl Spread Kp_Sp Kt_Sp 14 14 38 38 11 11 37 37
APPENDIX C
28 DAY COMPRESSIVE STRENGTH, WORKABILITY AND
DENSITY DATA
Mix No. w/c matrix Lgtwgt Aggregate Slump (mm) Flow (mm) Demould Density (Kg/ cu.m) Density @ 28 days (Kg/ cu.m) Comp Stren (MPa) 10 0.25 30 Lytag 100 320 - 2013 64.5 11 0.35 30 Lytag 125 390 - 1940 51.7 12 0.3 25 Lytag 0 min - 1937 54.5 13 0.25 35 Lytag 80 350 - 2007 64.7 14 0.35 25 Lytag 5 min - 1947 52.2 25 0.3 28 Lytag 100 345 1970 1977 60 26 0.3 32 Lytag 260 625 1973 1970 57.3 27 0.3 26 Lytag 50 300 1965 1960 57.2 28 0.3 29 Lytag 180 455 1998 1993 61 29 0.3 24 Lytag 25 260 1965 1963 58.5 35 0.25 28 Lytag 40 min 1988 1995 59 36 0.25 32 Lytag 210 580 1991 2015 57 37 0.35 32 Lytag 205 370 1927 1940 51.5 38 0.35 29 Lytag 150 360 1936 1950 51.5 43 0.25 35 Lytag 284 630 - 2015 62 15 0.25 30 Liapor 230 455 - 2027 75.2 16 0.3 30 Liapor 230 520 - 1987 65 17 0.35 30 Liapor 160 420 - 1983 60.5 18 0.25 35 Liapor 275 610 - 2010 73.7 19 0.3 25 Liapor 5 min - 2000 67.8 20 0.35 25 Liapor 10 min - 1977 61.3 31 0.35 28 Liapor 80 370 1999 2003 67.8 32 0.3 29 Liapor 230 530 1994 1997 67.7 33 0.25 28 Liapor 200 400 2028 2026 77.3 34 0.3 28 Liapor 180 425 2009 2000 69 39 0.35 31 Liapor 235 650 1940 1950 63 40 0.25 26 Liapor 15 min 1944 1943 72 41 0.25 27 Liapor 10 min 1946 1950 73.5 42 0.3 27 Liapor 115 430 1949 1950 68.5 43 0.25 35 Lytag 284 630 - 2015 62
APPENDIX D
MIX RECIPES
Mix Details
Mix Lightweight Matrix Nominal Mix Moisture content Absorption
No. Aggregate (%) w/c Volume sand LWA sand LWA
(cu.m) % % % % 8 Lytag 30 0.3 0.035 3.08 11.42 -1.06 7.04 10 Lytag 30 0.25 0.035 4.00 7.57 -1.98 5.94 11 Lytag 30 0.35 0.035 4.00 7.57 -1.98 5.94 13 Lytag 35 0.25 0.035 4.00 7.57 -1.98 5.94 14 Lytag 25 0.35 0.035 4.00 7.57 -1.98 5.94 15 Liapor 8 30 0.25 0.035 4.00 20.48 -1.80 0.87 16 Liapor 8 30 0.3 0.035 4.00 20.48 -1.80 0.87 17 Liapor 8 30 0.35 0.035 4.00 20.48 -1.80 0.87 18 Liapor 8 35 0.25 0.035 4.00 20.48 -1.80 0.87 19 Liapor 8 25 0.3 0.035 4.00 20.48 -1.80 0.87 20 Liapor 8 25 0.35 0.035 4.00 20.48 -1.80 0.87 25 Lytag 28 0.3 0.035 4.90 7.22 -2.70 6.78 26 Lytag 32 0.3 0.035 4.90 7.22 -2.70 6.78 27 Lytag 26 0.3 0.035 4.90 7.22 -2.70 6.78 28 Lytag 29 0.3 0.035 4.90 7.22 -2.70 6.78 29 Lytag 24 0.3 0.035 4.90 7.22 -2.70 6.78 31 Liapor 8 28 0.35 0.035 6.08 20.39 -3.88 0.64 32 Liapor 8 29 0.3 0.035 6.08 20.39 -3.88 0.64 33 Liapor 8 28 0.25 0.035 6.08 20.39 -3.88 0.64 34 Liapor 8 28 0.3 0.035 6.08 20.39 -3.88 0.64 35 Lytag 28 0.25 0.035 2.60 9.40 -0.40 5.80 36 Lytag 32 0.25 0.035 2.60 9.40 -0.40 5.80 37 Lytag 32 0.35 0.035 2.60 8.30 -0.40 6.80 38 Lytag 29 0.35 0.035 2.60 8.30 -0.40 6.80 39 Liapor 8 31 0.35 0.035 2.60 10.30 -0.40 0.40 40 Liapor 8 26 0.25 0.035 2.60 10.30 -0.40 0.40 41 Liapor 8 27 0.25 0.035 2.60 10.30 -0.40 0.40 42 Liapor 8 27 0.3 0.035 2.60 10.30 -0.40 0.40 43 Lytag 35 0.25 0.035 1.96 10.64 0.24 5.00
Negative figure for absorption denotes water inexcess of SSD condition LWA absorption values were measured (30 mins) for each set of mixes
The sand absorption value was calculated by measuring the actual moisture content and subtracting the moisture content for SSD condition.
