Special types of concrete Light weight concrete The concrete which has substantially lower mass per unit volume than the concrete made of ordinary ingredients is called lightweight concrete. The aggregates used are lighter in weight. The strength of light weight concrete blocks varies from 7 MPa (1000 psi) - 40 MPa (5800 psi). Some times Air Entrained Admixtures are also added to it giving resistance to freezing and thawing along with strength. Self weight of light weight concrete varies from 300 to 1850 kg/m3. The advantageous of this type of concrete are as follows:

1. It helps reduce the dead load 1 . It helps reduce the dead load. 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.

2. Light weight concrete have low thermal conductivity 2 . Light weight concrete have low thermal conductivity. (In extreme climatic condition where air condition is to installed, the use of light weight concrete with low thermal conductivity is advantageous from the point of thermal comfort and low power consumption.

3. 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.

Aerated concrete is one of the types of lightweight concrete Aerated concrete is one of the types of lightweight concrete. Produced by the addition of an air-entraining agent to the concrete (or a lightweight aggregate such as expanded clay aggregate or cork granules and vermiculite) is sometimes called cellular concrete, lightweight aerated concrete, variable density concrete, Foam Concrete and lightweight or ultra-lightweight concrete.

Pervious concrete is another type of light weight concrete Pervious concrete is another type of light weight concrete. It is used in permeable paving, contains a network of holes or voids, to allow air or water to move through the concrete. This allows water to drain naturally through it, and can both remove the normal surface-water drainage infrastructure, and allow replenishment of groundwater when conventional concrete does not. It is formed by leaving out some or all of the fine aggregate (fines). The remaining large aggregate then is bound by a relatively small amount of Portland cement. When set, typically between 15% and 25% of the concrete volume is voids, allowing water to drain at around 5 gal/ft²/ min (70 L/m²/min) through the concrete.

Fiber-reinforced concrete Fiber-reinforced concrete. The concrete matrix can be reinforced with short, randomly distributed fibers. Fibers may be metallic (primarily steel), synthetic (such as polypropylene, nylon, polyethylene, polyvinyl alcohol, and alkaliresistant glass), or natural (such as sisal, coconut, and rice husk). Such fibers are typically used in addition to conventional steel reinforcement, but in some applications as its replacement. For example, precast glass-fiber- reinforced building façade elements are widely used in the many countries in the world. By being uniformly distributed and randomly oriented, the fibers give the concrete matrix tensile strength, ductility, and energy absorption capacities. In particular, when these fibers are engineered to optimize the fracture energy, so-called high performance fiber-reinforced concrete is obtained, which has remarkable deformational characteristics and extraordinary resistance to blast and impact loads. In the concrete industry, it is very common to add small amounts of polypropylene fibers to reduce the extent of shrinkage cracking

Roller-compacted concrete Roller-compacted concrete. This type of concrete is formulated with very low contents of Portland cement and water and therefore is of relatively low-cost. It is often used for pavements and dams. It can be transported by dump trucks or loaders, spread with bulldozers or graders, and compacted with vibratory rollers. Because the cement content is so low, the heat of hydration does not cause the kind of problems encountered in dams built with conventional concrete

Ultra-high-strength concrete Ultra-high-strength concrete. Whereas concretes with compressive strengths of 6000 to 12,000 lb/in.2 (40 to 85 MPa) can now be categorized as high-strength, a new technology has been developed that results in strengths of 30,000 lb/in.2 (200 MPa) and higher. The key ingredient of this ultra-high-strength concrete is a reactive powder; therefore, it is also known as reactive-powder concrete. Other characteristics of this material are low water–cement ratios, carefully selected high-strength aggregates, and small steel fibers.

Self-leveling concrete Self-leveling concrete. The need for good workability has been mentioned. The need for highly skilled workers who can properly compact concrete at the construction site prompted researchers in Japan to optimize the mix design such that the fresh concrete can flow into place without the need for further vibration. The main challenge was to obtain a low- viscosity mix without the threat of segregation. This innovation is particularly important in applications with dense steel reinforcement, which traditionally have caused severe difficulties of producing high-quality concrete.

Green concrete. Concrete is by far the most widely used building material. Well over 10 billion tons are produced worldwide each year, requiring enormous natural resources. Also, it has been estimated that the production of 1 ton of Portland cement causes the release of 1 ton of carbon dioxide (CO2) into the atmosphere, a gas that is known to contribute to global warming. Together with the large amounts of energy required to produce Portland cement, the cement and concrete industry has a major impact on the environment worldwide. Efforts are underway to reduce this impact and transform the industry to conform to the principles of sustainable development. The most significant step is the replacement of Portland cement by other cementations or pozzolanic materials, preferably materials that are by- products of industrial processes, such as fly ash (the by-product of coal-burning power plants) and granulated blast furnace slag (a by-product of the steel industry). To reduce the need for virgin aggregate, recycled concrete is the most promising approach, because construction debris, in particular demolished concrete, constitutes a major component of solid waste that fills up sparse landfill capacity. For the concrete industry to maintain its dominant position within the construction industry, it is undertaking major efforts to make concrete a more “green” material.

Polymer concrete (Latex concrete): Adding a polymer latex to concrete can improve strength, ductility and durability. The latex is essentially a bonding agent which can be mixed integrally with the concrete and gives it superior adhesive properties. The material shows good freeze-thaw, abrasion and impact resistance which allows it to be used for patching and overlays on bridge and parking decks. Latex modified concrete is usually applied in thin layers, and it is possible to get traffic back on the decks within a few hours. Air-entraining agents should not be used with latex modified concrete. In fact, antifoaming agents may be needed to prevent excessive air contents. The polymer latex is added to the concrete mix in a water solution during mixing. Proportioning and batching procedures are handled normally. The latex can be added to the mix at the jobsite as with superplasticizers or pigments.