Literature review
Before proceed to predict concrete strength equation, it is essential to have a clear concept and understanding on concrete. Below are review of concrete compositions and some concrete properties.
1.1- Cement
C.Deepa et. al (2010) states that cement is made of a mixture of chalk or limestone together with clay. It contains adhesive and cohesive properties which allowing it to link mineral piece into a solid mass. Cement through chemical reaction (hydration) to form a hardened mass. Among different types of cement, Portland cement is the most commonly used as binding material in nowadays civil engineering. The name "Portland cement" was originated in a patent obtained by Joseph ASP din of Leeds, England in 1824.
1.2- Water
Water undertake two important roles in concrete mixture. The first one is to act chemical reaction with cement and carry out cement hydration. Second one is to make the concrete become smooth and workable. Water used in concrete mixture should be clean and free of organic matter, any clear, drink and fresh water is acceptable. Impure water should be avoided in use and amount of water must be control carefully as they will lead to undesirable effect on concrete strength.
1.3- Aggregate
Aggregate generally means the component of different size of
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Concrete compressive strength is an important factor within the mechanical properties. In most building structures, concrete strength is used to resist compressive forces and support load act on the buildings. Compressive strength could be one of the basic measurement to review the overall quality of the concrete. Mindess et.al. (2003) states that water to cement ratio (w/c) has a great impact in the strength of the concrete. The higher the w/c, the lower the compressive strength. The lower the w/c, the higher the compressive
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.
Almost no other material manages to carry such contradictory associations. Stigmatized on one hand, celebrated on the other, it evokes highly diverse reactions this material is cement. Cement is a finely ground powder binder, a substance that sets and hardens and can bind other materials together, when mixed with water forms a hardening paste of calcium silicate hydrates and calcium aluminates hydrates. Cement is used in mortar and concrete (bulk rock-like building material made from aggregate, sand, and water). By modifying the raw material mix and the temperatures utilized in manufacturing, compositional variations can be achieved to produce cements with different properties. Cement, chemically speaking, is a product including lime as the
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.
Aitcin P.C, “Cements of yesterday and today Concrete of tomorrow”, Cement and Concrete Research, Vol. 30, (2000), pp 1349 - 1359.
2) While many High Performance Concretes exhibits rapid stiffening and early strength gain, other’s may have long set times and low early strengths.
[20] BS Part 116: 1983. Testing Concrete and determination of compressive strength. British Standards Institution ;
Concrete is one of the world’s most popular construction materials. Some six billion tonnes of concrete is produced each year in the world, making it approximately one ton of concrete for every human being per year (Fardis, 2012, p.116). However, the lifecycle of concrete does not make it the most sustainable building material at the moment. Because of limited natural resources, concerns over green house gases, and landfill problems, concrete production is being cut-back, or at least cannot be increased to keep up with population increase. In this essay, I will look at what makes concrete an unsustainable material and possible solutions to make concrete a more sustainable material.
Aggregate: in cement concrete to gain good quality aggregates are used in two groups. Sand and coarse
Concrete behaves as a back bone to nations building team. Concrete is a composite construction material composed primarily of aggregate, cement, and water. There are many formulations, which provide varied properties. But one of the disadvantages with the conventional concrete is high self weight of concrete. This heavy weight will make it some extent uneconomical structural material. Many attempts made in the past to reduce the self weight to increase the efficiency of concrete.
In this report, we will introduce and illustrate on precast concrete, pre-stressed concrete, ready-mix concrete, reinforced concrete, terrazzo and Urbanite in details.
Cement is a finely ground compound of limestone and clay or marl (Chandigarh, 2001). It is used in hydraulic binding since it hardens and binds together aggregates and becomes waterproof thereafter. The most popular use of sand is in building and construction where it is used to bind sand and gravel to obtain concrete used in constructing houses, roads, water channels, among others. Yanbu Cement company produces different types of cement such as Portland cement types I, II, III and IV.
Generally the strength of concrete is represented by the crushing stress of concrete cube of size ………………………………..
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).
This porous region is important because of the fluids contained inside them. These fluids will have free particles on cement that have not been reacted as well as unreacted ions. This liquid phase creates a link between the hydrated cement and outside environment as fluids can slowly travel through these pores.
Water-reducing admixtures reduce the amount of mixing water needed to produce concrete of a required slump, to reduce the water-cement ratio and the water content. These admixtures reduce the water content by 5-10%. Adding this type of admixture to concrete will increase the slump if the water content is not reduced. Slump loss results in decreased workability and reduced time for placing the concrete. When the water-cement ratio is decreased, the strength of the admixture increases. Concretes with an equal contents of water, air content and the slump; the 28-day strength of a water-reduced concrete consisting of a water reducer can be 10-25% greater than concrete without the