DEPARTMEN
DEPARTMENT OF
T OF CIVIL ENGINEERING
CIVIL ENGINEERING
2014-2015
2014-2015
Seminar report on
Seminar report on
Lightweight Concrete
Lightweight Concrete
Submitted Submittedby:-SSM POLYTECHNIC COLLEGE
TIRUR
DEPARTMENT OF CIVIL ENGINEERING 2014-2015
CERTIFICATE
This is to certify that this is the bonafide record of seminar on
Lightweight Concrete has been presented by ANOOP.K , sixth semester Civil Engineering, SSMPTC, Tirur on………. In pa r-tial fulfillment of the requirement for the award of the Diploma in Com- puter Engineering under Directorate Of Technical Education, Kerala
State during the year 2014-2015.
Staff in charge: Head of Section:
ACKNOWLEDGEMENT
First of all I would like to praise the god for blessing me to com- plete this seminar successfully.I am deeply incepted to Mr. Moham-med Iqbal M (Head of department in Civil engineering, Seethi Sahib Memorial Polytechnic College ,Tirur) for providing me the opportuni-ty to present the seminar on this topic.
I extended my unexplainable gratitude towards all of my teach-ers; especially to Mr. Abdul Naser Kokkodi(Lecturer in Civil engi-neering, Seethi Sahib Memorial Polytechnic College, Tirur) & librari-ans who gave me a lot of information and supports for this seminar.I gave my heart full thanks to my friends & family, whom offered me all kind of supports for this.
CONTENTS
ABSTRACT 05 INTRODUCTION 06-07 BASIC CHARECTERS 08-09 HISTORY OF LWC 10-11 ADVANTAGES OVER NWC 12-13 APPLICATIONS 14 NEW OPPORTUNITIES AND CHALLENGES 15-16
CONCLUSION 17
ABSTRACT
Lightweight concretes can either be lightweight aggregate con-crete, foamed concrete or autoclaved aerated concrete (AAC). Such lightweight concrete blocks are often used in house construction. Nearly all LWACs are fire resistant. In addition, depending upon the densities and strength, the concrete can be easily cut, nailed, drilled, and chased with ordinary wood working tools. Lightweight concrete is expensive, but the cost is calculated not just on the basis of aggregates or LWAC. The bond between the aggregate and the matrix is stronger in the case of
LWAC than in normal concrete. Cement paste penetrate inside the aggre-gates due to their porous nature. Thus, there is very little or no ITZ be-tween the aggregates and the matrix. Simply, it’s a type of concrete made with lightweight aggregates.
INTRODUCTION
Lightweight concrete (brick) as known as AAC (Autoclaved Aer-ated Concrete) is a well-known constructing material all over the world; it was first invented by a Swedish Architect named Johan Axel Eriksson in 1923.Lightweight concrete contains no aggregate larger than sand, lime, thermal ash, synthetic fiber, cement, aluminum powder and water as binding agent. When AAC is mixed and cast in forms, several chemical reactions take place that give AAC its light weight (20% of the weight of concrete) and thermal properties. Therefore, lightweight concrete is quite light and may suffer extreme pressure as well as insulate the high and low temperatures.
In Japan, lightweight concrete is used to support the
build-ing foundation against the earthquakes. Lightweight concrete
technology is quite friendly with the environment by reducing
five times the amount of carbon dioxide of the production from
the raw material process till the recycle wastes process. Since
the born of lightweight concrete in building industry, baked
bricks (made from natural clays) in developed countries are
banded to protect the environment and national resources. On
the other hand, lightweight concrete with the gas bubbles
struc-ture (up to ⅛ inch in diameter) is applied popularly by
devel-oped countries with high technologies such as United States of
America, Germany, France, Japan, etc. in handling multiple
ge-ography technical issues such as making the foundation for
highways, anti-slip subsidence in the mountainous areas or weak
land areas to bring back huge economic benefits.
Because of its advantages, lightweight has taken an
im- portant part of developed countries such as Europe, North
America, and North Asia as well as the attention of some
devel-oping countries in replacing its traditional building material
which is red brick, regular concrete and clay block.
BASIC CHARACTERS
Lightweight concrete, similar to normal weight concrete, is a mix-ture of water, Portland cement or Ordinary Portland Cement (OPC), and aggregate. It is classified as structural or nonstructural concrete depend-ing on strength and compression ratdepend-ing, generally determined by the type of aggregate material used in the concrete mix. Lightweight aggregate concrete uses a variety of aggregates with lower density than normal weight concrete.
Structural concrete, whether an approved lightweight or a normal weight concrete, is used for applications calling for a high level of strength and compression rating. These might be highway overpasses, bridges, high-rise buildings, and construction in areas prone to earth-quakes. Advantages of structural lightweight aggregate concrete with a correspondingly reduced weight load include reduced dead loads, or weight of the structures it's used to build, and more efficient transport.
While not approved for many structural applications, nonstructural lightweight concrete is used where normal or a more dense structural lightweight mix would be impractical. Roof tiles made of lightweight concrete are lighter and require less robust truss systems. The combina-tion of strength, weather resistance, and reduced weight often makes lightweight aggregate concrete mix and lightweight blocks a good choice for non-traditional residential buildings.
Aggregates used to make lightweight aggregate concrete vary. Ex- panded shale, slate, and clay, often fired in a kiln to increase porosity, are among aggregates used for structural lightweight concrete. Other porous material, such as air-cooled blast furnace slag, is often used.
Insulation is often a factor in selecting an aggregate for nonstruc-tural lightweight concrete. A lightweight aerated concrete may be used to make both lightweight panels and lightweight blocks suitable for a variety of construction, including some foundation stem walls. Lightweight aer-ated concrete may be made in a variety of ways, such as forcing air into slurry of OPC and a porous material, or by using a stable foam product as an aggregate.
Perlite and vermiculite are natural minerals that, when heat-treated, can be mixed with OPS to produce a nonstructural lightweight aggregate concrete. The product is often used for decorative concrete treatments, roof tiles, and other lightweight applications. This lightweight concrete is often used in jobs requiring insulation from heat and sound.
Structural lightweight aggregate concrete might typically require a density or unit weight of 90 to 115 lb/ft³ or (1440 to 1840 kg/m³) and a compression rating of 2500 psi or (1700 MPa), which is about 65% of the density or unit weight of normal concrete. Nonstructural lightweight con-crete might have a density or unit weight as low as 35 lb/ft³ or (561 kg/m³). When considering lightweight concrete for a construction job, it is generally a good practice to consult a qualified engineer or architect for specifications.
HISTORY OF LIGHTWEIGHT CONCRETE
The use of lightweight (LWAC) can be traced to as early as 3,000BC, when Mohenjo-Daro and Harappa were built during the Indus Valley civilization. In Europe, the use of LWCA occurred 2,000 years ago when the Romans built Pantheon, the aqua ducts, and the Coliseum in Rome. The pumice is still used today in certain countries, such as Germa-ny, Italy and Japan. In some places like Malaysia, palm oil shells are used for making LWAC.
The Roman Temple Constructed using LWAC
Earlier lightweight aggregates (LWAs) were of natural origin, mostly volcanic: pumice, tuff. They function as active pozzolanic materi-als when used when used as fine aggregates. Techniques have been de-veloped to produce them in factories. These are produced from the natural raw materials like expanded clay, shale, slate, etc., as well as from
by-Pont du Gard built by romans (2000 years ago)
Today, lightweight aggregates are produced in a very wide range of densities varying from 50kg/m3 from expanded perlite to 1000kg/m3 for clinkers. It is possible to make LWAC of 80Mpa compressive strength Nearly all LWACs are fire resistant. In addition, depending upon the densities and strength, the concrete can be easily cut, nailed, drilled, and chased with ordinary wood working tools.
ADVANTAGES OVER NORMAL WEIGHT CONCRETE
One of the main advantages of conventional concrete is the self-weight of concrete. Density of normal concrete is of the order of 2200 to 2600. This self-weight will make it to some extend an uneconomical structural material.
Self
-
weight of light weight concrete varies from 300 to 1850kg/m3.
It helps reduce the dead load, increase the progress of building
and lowers the hauling and handling cost.
The weight of building on foundation is an important factor in the
design, particularly in case of weak soil and tall structures. In framed structure, the beam and column have to carry load of wall and floor. If these wall and floor are made of light weight concrete it will result in considerable economy.
Light weight concrete has low thermal conductivity. In extreme
climatic condition where air condition is to install the use of light weight concrete with low thermal conductivity is advantageous from the point of thermal comfort and low power consumption.
Only method for making concrete light by inclusion of air. This is
achieved by :
-o Replacing original mineral aggregate
o By introducing gas or air bubble in mortar
o By omitting sand fraction from concrete. This is called no –
Light weight aggregate include pumice, saw dust rice husk, thermo
Cole beads, formed slag. Etc.
Light weight concrete aggregate exhibit high fire resistance.
Structural lightweight aggregate’s cellular structure provides
internal curing through water entrainment which is especially beneficial for high
-
performance concrete lightweight aggregate has better thermal properties, better fire
ratings, reduced shrinkage, excellent freezing and thawing durability, improved contact between aggregate and cement matrix, less micro
-
cracking as a result of better elastic compatibility, more blast resistant, and has better shock and sound absorption, High-
Performance lightweight aggregate concrete also has less cracking, improved skid resistance and is readily placed by the concrete pumping method Aerated concrete is made by introducing air or gas into a slurry
composed of Portland cement.
No fine concrete is made up of only coarse aggregate, cement and
water. This type of concrete is used for load bearing cast in situ external walls for building. They are also used for temporary structures because of low initial cost and can be reused as aggregate.
APPLICATIONS
Light weight concrete is a good alternative for normal weight con-crete. It widely uses in the following
areas:- Building industry
Road Construction
Mining
Land filling
NEW OPPORTUNITIES AND CHALLENGES
When constructing buildings, especially high-rise building, the in-vestor always tries to make the structures sustainable and cost-effective. The way to acquire both of these two depends mostly on the foundation of the building. However, the foundation depends on the geology and the total mass of the whole project. Changing the geology is difficult, more feasible is to find ways to reduce the loading capacity. Hence, the birth of light weight brick is considered as a revolution for the construction indus-try. Light weight bricks are made from cement; thermal ash, synthetic fi- bers (possible) and foaming agent to make the composition inside possess chambers forming as a honeycomb. This helps the brick become porous and reduce the weight of brick from 600 kg/m3 to 900kg/m3 (D600 -D900) as ½ lighter than common brick, and easier to drill, cut or nail di-rectly onto the tile surface. The brick can even float on water.
There are various kinds and sizes of lightweight concrete to be used widely from small projects to high rise buildings. The costs also suit each project. Lightweight concrete is a great construction material. It is not only low derivative, high thermal resistant, envi-ronmental protected but also energy-cost saving compared to traditional materials. Pro-ducing
traditional materials waste industrial land, coal and in the same time, causes greenhouse effect by eliminating millions tons of CO2. Converse-ly, lightweight con-crete limits environmental bad impacts and recycles a significant amount of industrial waste, turning waste into useful materi-als.
of the total building materials. With the global trend, Vietnam Govern-ment is trying to take full advantage of lightweight concrete as well by approving the Decision No. 121/2008/QD-TTg dated 29/08/2008 of the Prime Minister. The Decision shows the master plan and route for devel-oping materials in Vietnam till 2020: lightweight concrete in 2010 will account for 10% to 15% and in-crease from 20% to 25% in 2015 and in 2020 the rate will reach 30% to 40%. Under-standing the great opportuni-ty, Thien Nam Phuong Co., Ltd is established to manufac-turer light-weight concrete with development objective not only to cover South Market of Vietnam but also the whole domestic market and export to oth-er countries in the near fu-ture. The company’s goal is to produce and sell 150,000 m3 / year. Although using lightweight concrete provides much economical and technical efficiency, there are still a lot of challenges that Government and manufacturer have to confront.
CONCLUSION
As a construction material, lightweight concrete is a good
alterna-tive for normal weight concrete.it has so many advantages over normal weight concrete.
The use of lightweight (LWAC) can be traced to as early as
3,000BC, when Mohenjo-Daro and Harappa were built during the Indus Valley civilization.
Today, lightweight concrete is widely used for Building industry,
Road Construction, Mining, Land filling, Tunnels, etc.
There are several new opportunities and challenges in the field of
