Types of concrete

Types of concrete

Different types of concrete are produced depending upon the end application. The various types of concrete include the ones listed below:

• High strength concrete
• Precast concrete
• Pre-stressed concrete
• Green concrete
• Hardened concrete
• Ready mix concrete
• Reinforced concrete
• Fresh concrete
• Light weight concrete

Pre-stressed Concrete:

These are the types of reinforced concrete which the steel reinforcements are controlled in a tension when production so as to attain stiffness. By such doing, a lesser amount of steel used and concrete is kept in compression, allowing it to take more loads before overcoming the compression. The procedure of pre-stressing of concrete eliminates cracks. Pre-stressed concrete use little steel compare with reinforced concrete and it is commonly used. This is durable and free of maintenance.

Glass concrete:

Recycled glass used to replace an aggregate in concrete is now more accepted in present days. It brings down the aesthetic request of the concrete. Research has indicates improve elongated strength and enhanced thermal insulation because of its good thermal characteristics of the glass aggregate, (Poutos et al., 2008).

High performance concrete (HPC)

These kind of concrete go beyond the characteristics and construction of plain concrete. Plain and exceptional materials are made to construct these particularly design concretes which should fit up a combining of execution needs. Particular mixing, placing and curing patterns is required to make a treated high performance concrete. General execution tests which typically essential that show fulfilment on precise task desires ASCE (1993), Russel (1999), and Mitchell (2001). In it strength, durability and high modulus of elasticity, high performance concretes have been mainly applied in tunnels, bridges and high structures therefore; strength is not at all times the main essential characteristics. For instance, a normal strength concrete which has higher durability and has lower permeability is referred to have high performance characteristics, Bickly and Fung,(2001) shown that 40mpa (6000psi) high performance concrete for bridges can be efficiently made by attaining durability components for air void system and resistance to chloride infiltration.

Roller compacted concrete:

This type of concrete is also referred to as rollcrete, is a small cement firm concrete placed by skills lent by earthmoving and paving. The concrete is put outside to be covered, and is compressed in place by huge weighty rollers usually for earthwork. concrete mix attain a lofty density and cures for some time in a well-built monolithic block, (Portland cement Association, 2008).

Pervious concrete:

This is the combination of particularly placed coarse aggregate, cement, water with few   or excluding fine aggregates. Pervious concrete can be referred to as no fines or porous concrete mixing aggregates by cautiously controlled procedure produce a paste which coats and binds aggregate molecules. The set concrete comprises interrelated air spaces calculation roughly fifteen to twenty-five per cent. Water enters into the void in a pathway to the soil beneath, Lancaster L. (2005).

Light weight concrete

Structural light weight concrete (LWC) are usually produced by replacing a whole or a part of natural normal weight aggregate by artificial or natural light weight aggregate (LWA).There are many types of lightweight concrete and their properties cover wide ranges, such as: elastic properties, compressive and tensile strength, time dependent properties, durability, fire resistance, etcas dependent on the type of aggregate utilized in the concrete. Structural lightweight aggregate concrete is defined as concrete which is made with lightweight aggregates conforming to ASTM C 330.

It has a compressive strength of 2,500 psi (17MPa) at 28 days of age when tested in accordance with methods stated inASTM C 330 and has a dry density not exceeding 1,840 kg/m3 as determined by ASTM C 567, but job specifications gives room for unit weights up to 1,920 kg/m3 or more. Such aggregates are either natural or artificial and are available in various parts of the world. Oyster shell is a type of natural lightweight aggregates used to lighten in this study, and it is found abundantly in coastal areas of the world e.g. in countries like Chile, China, Ethiopia, Greece, Nigeria and Spain as stated by Guo et al; (1999).

Glenn (2004); in his statement describe Lightweight Aggregates as aggregates with special use that have an apparent specific gravity considerably below the normal conventional concrete that were used before, which made it obvious that lightweight aggregate is one of the critical elements that makes concrete flexible and versatile in making the overall structural design and specifications as to meet the construction requirements as argued by Chandra (2002).

The range of lightweight aggregate is extensive in nature from extremely light materials used for non-structural concrete and insulation, all the way to expanded clays and shales used for structural concrete as stated byNeville and Brooks, (1987).

This makes it clear that the lightweight aggregate in the concrete is mainly aimed to achieve high level of physical stability and compressibility through effectively utilization of the physical qualities of the aggregate materials.

This is further justified in the arguments of Chandra (2002) who argues that the lightweight aggregate in the concrete is a major step towards innovation in the field of engineering.

Also, the strength and the air trapped in each individual particle of the components of the aggregate materials are inversely proportional to each other thus making it clear that in order to gain lightweight aggregate the amount of air trapped in the individual particles must be high thus making it clear that the strength of the concrete thus obtained is low. The above relationship stated provides the guidance to ensure the balance between the air trapped and the strength required in the concrete mix thus making the overall lightweight aggregate concrete customizable to meet the structural requirements of the application on hand.