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Superplasticizers (SPs), also known as high range water reducers, are additives used for making high-strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more.
Water reducers offer several advantages in their use, listed below: reduces the water content by 5-10%; decreases the concrete porosity; increases the concrete strength by up to 25% (as less water is required for the concrete mixture to remain workable) increases the workability (assuming the amount of free water remains constant)
These low range water reducing dispersants are commonly manufactured from lignosulfonates, a by-product from the paper industry. High range superplasticizers (dispersants) have generally been manufactured from sulfonated naphthalene condensate, although polycarboxylic ethers represent more modern alternatives. Both of these high range water ...
Self-consolidating concrete or self-compacting concrete (SCC) [1] is a concrete mix which has a low yield stress, high deformability, good segregation resistance (prevents separation of particles in the mix), and moderate viscosity (necessary to ensure uniform suspension of solid particles during transportation, placement (without external compaction), and thereafter until the concrete sets).
A reduction of 40 percent of Portland cement in the concrete mix is usually feasible when replaced with a combination of pozzolanic materials. Pozzolans can be used to control setting, increase durability, reduce cost and reduce pollution without significantly reducing the final compressive strength or other performance characteristics.
The performance of a concrete mix can be altered by use of admixtures. Admixtures can be used to reduce water requirements, entrain air into a mixture, to improve surface durability, or even superplasticise concrete to make it self-levelling, as self-consolidating concrete, [14] the use of admixtures requires precision in dosing and mix design ...
A cement accelerator is an admixture for the use in concrete, mortar, rendering or screeds. The addition of an accelerator speeds the setting time and thus cure time starts earlier. [ 1 ] This allows concrete to be placed in winter with reduced risk of frost damage. [ 2 ]
The cement reacts with the water through a process called concrete hydration [4] that hardens it over several hours to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. [5] This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed.