Superplasticizer Admixtures for Concrete

Superplasticizers are the improved construction chemical additives over plasticizers with highly effective plasticizing effects on wet concrete. Superplasticizers result in a substantial enhancement in workability, reduction of water content up to 30% may be achieved by the use of concrete superplasticizers. Superplasticizers can be used at higher dosages than conventional plasticizers in the range of 0.5% to 3% by weight of cement.

Superplasticizers transform stiff, low-slump concrete into flowing, pourable, easily placed concrete. They can improve workability, speed finishing, increase strength, conserve cement and help reduce shrinkage and thermal cracking.

Superplasticizer for cement can be used in three ways: to create flowing, self-leveling concrete without increasing water, without reducing cement and without sacrificing strength; to produce workable, high-strength concrete by reducing the water and thus the water-cement ratio; or, to save cement by reducing both the water and cement contents while maintaining the same water-cement ratio and the same workability. Although sodium lignin sulfonate retards the setting time by about an hour when used with certain cement types, superplasticizers generally do not affect the setting time. At most, they may retard the initial set for about 15 minutes.

Finishing problems, however, can occur. Because superplasticizer mixes, especially flowing superplasticizer mixes, have a proportionately large volume of mix mortar, they tend to be sticky. The concrete pulls or drags on the trowel, the surface tears, and the mix tends to move under the finisher's weight. Using coarser fine aggregate or a higher proportion of coarse aggregate stiffens the mix and provides a less-mortar-intensive appearance. Another remedy is simply to delay finishing. A superplasticizer is not a cure-all admixture; it has its own problems, which must be taken into account. Nonetheless, the dramatic transformation of stiff concrete into flowing concrete by adding a superplasticizer instead of water may be the most significant breakthrough in concrete technology since the development of air-entraining agents.

But the effectiveness of an admixture depends on several factors including type and amount of cement, water content, mixing time, slump, and temperatures of the concrete and air. Sometimes, effects similar to those achieved through the addition of admixtures can be achieved by altering the concrete mixture-reducing the water-cement ratio, adding additional cement, using a different type of cement, or changing the aggregate and aggregate gradation.

As a leading manufacturer and supplier of construction chemicals in China, Henan Kingsun Chemical Co., Ltd. has been committed to research and produce concrete admixtures for many years. Kingsun produces high-quality many different superplasticizers. Visit this site http://kingsunconcreteadmixtures.com to get more details about Kingsun products.