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Chapter 1 :
Concrete and steel are materials commonly used in building construction. Concrete is formed by mixture of aggregates which are sand and stone, and bonded together by water and cement with the proper ratio of 1:2:4 or 1:3:6 which is commonly used. Steel is a material that is manufactured under carefully controlled condition by which its properties are determined in a laboratory. Combining concrete and steel gives increased strength to resist heavy loads to increase the lifetime of the structure. Even though concrete and steel give many advantages on building, they can also cause failure to the structure thru the impropriate procedure work, and lacks of efficient control and monitoring mechanism (A.M. Neville, 2002), which has happened before where the Public Works Department in Petaling Jaya collapsed due to the structure failure (StarBiz, 2009) and Highland Tower in Ulu Klang due to piling failure (New Straits Times, 2000).
The list of previous dissertation topics by building surveying students shows that there has never been a study or research done on concrete failure in the Industrial Zone. Due to the importance of awareness and understanding of concrete failure, the dissertation topic on "The Causes & Effects of Concrete Failure on Residential Building Surrounding Industrial Zone" is chosen for research and case study. The idea on this topic also came when conducting condition survey on the Shah Alam Commercial building where it is important to understand the effects of the emissions produced from industrial area to the concrete structures in order to prevent concrete failure. The aim of dissertation is to give an insight on the causes of the defects, share what measures are taken by the building authority to prevent it and to find the result on the majority causes of the failure and its effect in real case study.
The objectives of dissertations are:
To study the causes and effects of concrete failure to the building structure
To investigate and study the causes and effects of concrete failure of the real life cases i.e buildings in the industrial areas
To come up with recommendations to prevent or minimise the concrete failure
The scopes of the dissertation are:
Literature review on concrete, type of cement and causes of the concrete failure.
Case study on the affected residential buildings surrounding industrial zone at section 25 Shah Alam, Klang Valley, and Petaling Jaya.
Produce questionnaire and conduct interviews with the contractors, clients, consultant or building maintenance personnel.
Analysis of the results based on site observations, reports and interviews
To give recommendation based on the result to prevent or minimise the concrete failure on structure.
The table below shows the procedures to reach the goal for my dissertation.
FINDING & ANALYZE
The dissertation consists of 6 chapters. The dissertation starts with the introduction of the project which includes scopes, objective, and the aims of the project which are stated as chapter 1.
Chapter 2 is a literature review on concrete. This includes description on the history of concrete and cement, different types of cement,comparisons between Ordinary Portland Cement (OPC) Sulphate Resistant Portland Cement (SRPC),types of concrete failure, sources and causes of concrete failure and the main theories of the concrete failure.
Chapter 3 discusses the analysis and results of the interviews and questionnaires on concrete failure. The experiences of the relevant people interviewed will be shared in this chapter.
Chapter 4 gives the detailed report of the case study including the site condition surveying results which consists of the study of building condition. The investigation and site observation on the causes and sources of defects and the remedies will be discussed.
The analysis of the findings and the results of the case study will be captured in chapter 5 which include graphs and discussions. Based on the results, the effectiveness of the remedies will be evaluated in this chapter.
The last chapter will conclude the case study and gives recommendations which includes the procedures on preparation and designing a building.
This Chapter is a literature review on concrete which started with the description on the history of concrete and cement. The objectives of this chapter is to conducting a research based on the different types of cement, comparisons between Ordinary Portland Cement (OPC) Sulphate Resistant Portland Cement (SRPC), types of concrete failure, sources and causes of concrete failure and the main theories of the concrete failure.
2.2 History of Concrete and Cement.
In around 2,500 BC, Pyramids was the first recorded structure to used cement. The ancient Egyptian constructed Pyramid by mixing mud with straw to bind dried bricks and by adding gypsum cement and lime.Then, the Greek and the Roman found that by adding lime and water, sand and crushed stone or brick and broken tiles, its produce compressional strength and created the first structural material known as concrete. The Pantheon in Rome, was recorded the first structure used concrete mixture and proven of the success of Roman invention which still standing until today. In 1756, concrete was modernise by the British engineer, John Smeaton by mixing powered brick into the cement and adding pebbles as a coarse aggregate. In 1824, Portland Cement was invented by the english inventor, Joseph Aspdin by burning ground limestone and clay together which change the chemical properties of the materials and produce high quality of cement. It became the first true artificial cement ever produce and remained its production until today. 20 years later, the parisian inventor, Joseph Monier invented reinforce concrete, which are the combination of concrete and steel which produce the tensile or bendable strength of metal and the compressional strength of concrete to withstand heavy loads (C.L. Page And M.M. Page, 2007).
2.3 Different Types of Cement.
Portland Cement are the major materials to produce another types of cement either by changing or reducing or increasing the chemical properties of the material. Below stated some of the different types of cement and its characteristic (V.S. Ramachandran, 1984).
Ordinary Portland Cement
Ordinary Portland cement (OPC) is the most important type of cement.
The OPC was classified into three grades, namely 33 grade, 43 grade and53 grade depending upon the strength of the cement at 28 days when tested as per IS 4031-1988. But the actual strength obtained by these cements at the factory are much higher than the specifications.
Rapid Hardening Cement
This cement is similar to ordinary Portland cement. As the name indicates it develops strength rapidly and as such it may be more appropriate to call it as high early strength cement.
Rapid hardening cement which develops higher rate of development of strength should not be confused with quick-setting cement which only sets quickly.
Rapid hardening cement develops at the age of three days, the same strength as that is expected of ordinary Portland cement at seven days.
Therefore, rapid hardening cement should not be used in mass concrete construction.
In pre-fabricated concrete construction.
Where formwork is required to be removed early for reuse.
Road repair works.
In cold weather concrete where the rapid rate of development of strength reduces the vulnerability of concrete to the frost damage
Extra Rapid Hardening Cement
It is necessary that the concrete made by using extra rapid hardening cement should be transported, placed and compacted and finished within about 20 minutes.
It is also necessary that this cement should not be stored for more than a month.
Extra rapid hardening cement accelerates the setting and hardening process.
A large quantity of heat is evolved in a very short time after placing.
The acceleration of setting, hardening and evolution of this large quantity of heat in the early period of hydration makes the cement very suitable for concreting in cold weather.
Sulphate Resisting Cement
Ordinary Portland cement is susceptible to the attack of sulphates, in particular to the action.
Their expansion within the frame work of hardened cement paste results in cracks and subsequent disruption.
Sulphate attack is greatly accelerated if accompanied by alternate wetting and drying which normally takes place in marine structures in the zone of tidal variations.
Concrete to be used in marine condition;
Concrete to be used in foundation and basement, where soil is infested with sulphates;
Concrete used for fabrication of pipes which are likely to be buried in marshy region or sulphate bearing soils;
Concrete to be used in the construction of sewage treatment works
Quick Setting Cement
This cement as the name indicates sets very early.
The early setting property is brought out by reducing the gypsum content at the time of clinker grinding.
This cement is required to be mixed, placed and compacted very early.
It is used mostly in under water construction where pumping is involved.
Use of quick setting cement in such conditions reduces the pumping time and makes it economical. Quick setting cement may also find its use in some typical grouting operations.
Super Sulphated Cement
This cement is rather more sensitive to deterioration during storage than Portland cement.
This cement has high sulphate resistance. Because of this property this cement is particularly recommended for use in foundation, where chemically aggressive conditions exist.
As super-sulphated cement has more resistance than Portland blast furnace slag cement to attack by sea water, it is also used in the marine works. Other areas where super-sulphated cement is recommended include the fabrication of reinforced concrete pipes which are likely to be buried in sulphate bearing soils. The substitution of granulated slag is responsible for better resistance to sulphate attack.
When we use super sulphated cement the water/ cement ratio should not be less than
0.5. A mix leaner than about 1:6 is also not recommended
Low Heat Cement
It is well known that hydration of cement is anexothermic action which produces large quantity of heat during hydration.
Formation of cracks in large body of concrete due to heat of hydration has focussed the attention of the concrete technologists to produce a kind of cement which produces less heat or the same amount of heat, at a low rate during the hydration process.
Cement having this property was developed in U.S.A. during 1930 for use in mass concrete construction, such as dams, where temperature rise by the heat of hydration can become excessively large.
A reduction of temperature will retard the chemical action of hardening and so further restrict the rate of evolution of heat. The rate of evolution of heat will, therefore, be less and evolution of heat will extend over a longer period.
Portland Pozzolana Cement
The history of pozzolanic material goes back to Roman's time. The descriptions and details of pozzolanic material will be dealt separately under the chapter 'Admixtures'.
A pozzolanic material is essentially a silicious or aluminous material which while in itself possessing no cementitious properties, which will, in finely divided form and in the presence of water, react with calcium hydroxide, liberated in the hydration process, at ordinary temperature, to form compounds possessing cementitious properties.
The pozzolanic materials generally used for manufacture of PPC are calcined clay or fly ash.
Portland pozzolana cement produces less heat of hydration and offers greater resistance to the attack of aggressive waters than ordinary Portland cement. Moreover, it reduces the leaching of calcium hydroxide when used in hydraulic structures. It is particularly useful in marine and hydraulic construction and other mass concrete constructions.
For hydraulic structures;
For mass concrete structures like dam, bridge piers and thick foundation;
For marine structures;
For sewers and sewage disposal works.
For manufacturing various colored cements, either white cement or grey Portland cement is used as a base.
The use of white cement as a base is costly. With the use of grey cement, only red or brown cement can be produced.
Coloured cement consists of Portland cement with 5-10% of pigment.
The pigment cannot be satisfactorily distributed throughout the cement by mixing, and hence, it is usual to grind the cement & pigment together.
Ordinary cement mortar, though good when compared to lime mortar with respect to strength and setting properties, is inferior to lime mortar with respect to workability, water retentivity,shrinkage property and extensibility.
Masonry cement is a type of cement which is particularly made with such combination of materials, which when used for making mortar, incorporates all the good properties of lime mortar and discards all the not so ideal properties of cement mortar.
This kind of cement is mostly used, as the name indicates, for masonry construction.
It contains certain amount of air-entraining agent and mineral admixtures to improve the plasticity and water retentivity.
Concrete made with ordinary Portland cement shrinks while setting due to loss of free water. Concrete also shrinks continuously for long time. This is known as drying shrinkage.
Cement used for grouting anchor bolts or grouting machine foundations or the cement used in grouting the prestress concrete ducts, if shrinks, the purpose for which the grout is used will be to some extent defeated. There has been a search for such type of cement which will not shrink while hardening and thereafter. As a matter of fact, a slight expansion with time will prove to be advantageous for grouting purpose. This type of cement which suffers no overall change in volume on drying is known as expansive cement.
Cement of this type has been developed by using an expanding agent and a stabilizer very carefully. Proper material and controlled proportioning are necessary in order to obtain the desired expansion.
One type of expansive cement is known as shrinkage compensating cement. This cement when used in concrete, with restrained expansion, induces compressive stresses which approximately offset the tensile stress induced by shrinkage.
IRS-T 40 Special Grade Cement
IRS-T-40 special grade cement is manufactured as per specification laid down by ministry of Railways under IRST40:1985.
This cement can be used with advantage for other applications where high early strength concrete is required. This cement can be used for prestressed concrete elements, high rise buildings, high strength concrete
High Early Strength Cement
Development of high early strength becomes an important factor, sometimes, for repair and emergency work.