Concrete is a composite material, which is made of three components water aggregate and Portland cement. Concrete is strong in resisting compression. It can also absorb tension in use where tensile stress has to be accommodated. The ingredients in the concrete are so that the concrete has strength and is durable (parrot, L 2002). According to (p. Mehta 2006)) concrete has a complex microstructure and is heterogeneous. For this reason it is difficult to constitute realistic models of its microstructure. Concrete behaviour under stress is explained only when the cement paste aggregate interfaces is treated as a 3rd phase of the concrete microstructure.
Fig. 1 on the left side is a polished section of concrete specimen and on the right it’s the microstructure of a hydrated cement paste.
Sulphate attack is described as the deterioration of concrete over a period of time; this affects the strength as well as
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On ground floor slabs sulphate attack can cause structural damage to the main walls of the building. This happens when the materials underneath the slabs contain sulphate and it moves on to the concrete and this will result in it expanding. When the slab heaves the internal walls, which are built off the slab, will be lifted and this may likely cause damage to the whole structure above. If delayed ettringtite formation occurs it can cause existing structure to crack and spall. The concrete in the north east is in contact with pyrites- containing red shale colliery waste backfill, this means the Silverlink site has more potential of getting thaumasite sulphate attack (TSA), however when site investigations were conducted it was found that the A19 site had no contaminations therefore unlikely to get sulphate attack. In addition it has been proven that there isn’t any serious damage that can be done to concrete or masonry due to thaumasite attack even in cool or damp
they're not. Concrete is to cement as a cake is to flour. Concrete is a mixture
(Mazzassa – Lea's science). Calcium silicate hydrate is the fundamental result of lime-pozzolan response. Calcium aluminous hydrate, hydrated gehlenite, calcium carboaluminate, ettringite and calcium aluminous monosulfate are a percentage of alternate items that outcome from the lime-pozzolan response notwithstanding calcium silicate hydrate. (Admixtures for cement T.erdogan). The hydration between slica of pozzolans and calcium hydroxide are given by mathematical statement.
Most people may not realise but concrete plays a vital part in our lives daily. It shapes and creates the built environment in which we are surrounded by, such as schools, bridges, roads, housing, hospitals, dams and so much mores. Concrete is the most used man made material in the world, averaging around 3 tonnes annually for each person. In comparison with other building materials such as wood, steel, plastic and aluminium, over twice as much concrete is used globally than any of these materials. It is the material choice of most purposes due to its strength, durability, thermal mass and its cost.
In this paper we have studied compressive strength of concrete by replacing natural aggregate with recycled aggregate by 25%, 50% and 75%.This mixture formed in the sample of cubes of dimension 150x150x150mm3.
Richard P, and Cheyrezy M, “Composition of Reactive Powder Concrete”, Cement and Concrete Research, Vol. 25, No.7, (1995), pp. 1501 – 1511.
2) While many High Performance Concretes exhibits rapid stiffening and early strength gain, other’s may have long set times and low early strengths.
[17] BS 4550-3.4:1978. Methods of testing cement, Physical tests, Strength tests. British Standards Institution ; 2007.
Aggregate: in cement concrete to gain good quality aggregates are used in two groups. Sand and coarse
Concrete is a composite material used widely in the construction industry. Concrete is basically a mixture of cement, water, aggregates and admixture (sometimes). Cement is a fine gray powder that consists of oxidizes calcium, silicon and aluminum. The aggregate used is normally gravel, crushed stone or sand. Admixture is a solid or liquid substance that gives a certain characteristics of the concrete. The cement reacts with water chemically and binds the aggregates together through a process called hydration during hardening or curing of concrete. It means that water helps in the hardening of the concrete while the cement bind the aggregate and also react with water to form a solid mass.
Throughout the construction industry, technology plays a role to help ease the completion of a project to all of the parties involved. The amount of technology application in the industry supports the belief that technology has a positive impact on project productivity. One of the main materials used in the construction industry that surrounds us every day, in which we overlook, is concrete. Concrete is an art form, in which it takes time and talent in order for it to be used efficiently, to produce its high strength and longevity. However, the downfall of this material is that it is extremely costly and nearly impossible to form it to an aesthetically pleasing surface. In spite of this, what if I told you that there is hope? That the dream of a material made of concrete, producing the same qualities, can be formed to any shape, and used anywhere was a reality.
A measure of how well concrete will handle freezing and thawing, wetting and drying, and physical wear.
In figure (2.26), eight equations proposed by different researchers have been plotted for lightweight concrete, as shown in table (2.12). The experimental splitting tensile strength values are calculated as follows: Eq. (2.23), (2.24), (2.25) (2.26) for cube specimens and (2.27), (2.28), (2.29), (2.30) for cylinder specimens. The splitting tensile strength of lightweight concrete for Eq. (2.23) ranged from 2.8 – 3.5 MPa, as shown in figure (2.23).
...nd Calderwood 1978; Suaris and Shah 1984), because it requires higher energy to split the fibers from the concrete.
In figure (2.26), eight equations proposed by different researchers have been plotted for lightweight concrete, as shown in table (2.12). The experimental splitting tensile strength values are calculated as follows: Eq. (2.23), (2.24), (2.25) (2.26) for cube specimens and (2.27), (2.28), (2.29), (2.30) for cylinder specimens. The splitting tensile strength of lightweight concrete for Eq. (2.23) ranged from 2.8 – 3.5 MPa, as shown in figure (2.23).
Previous study about the Ordinary Portland Cement (OPC), High Performance Concrete (HPC), And Ultra High Performance Concrete(UHPC) there are different result about the penetration of chloride ions to the specimen. This because, the reinforced concrete are exposed to harsh environment yet often expected to last with little or no maintenance for a long periods of time. The lacking maintenance of the concrete may cause this problem become worse and the concrete may not suitable to used.