Expansive Cement

expansive cement

[ek′span·siv si′ment]
(materials)
A type of hydraulic cement, usually of high sulfate and alumina content, that expands after hardening to compensate for drying shrinkage.

Expansive Cement

 

the generic name for a class of cements that increase in volume during hardening. In most such cements, the expansion is due to the formation of highly basic calcium sulfoaluminate hydrates in the hydrating binder. The volume of these calcium compounds is 1.5 to 2.5 times greater than the volume of the initial solid components as a result of a large quantity of chemically bonded water. The total expansion ranges between 0.2 and 2 percent; the strength ranges between 30 and 50 meganewtons/m2.

In the USSR, the most widely used types are waterproof expansive cement, expansive portland cement, gypsum-alumina expansive cement, and stressing cement. All expansive cements harden best and exhibit the greatest expansion in the presence of moisture. Since they are highly waterproof, expansive cements are used for sealing joints between prefabricated rein-forced-concrete structural members, for reliable waterproofing in certain hydraulic engineering structures, and for manufacturing of reinforced concrete pressure pipes.

expansive cement, sulfoaluminate cement

A cement which when mixed with water forms a paste that tends to increase in volume, after setting, to a significantly greater degree than portland cement paste does; used to compensate for volume decrease due to shrinkage or to induce tensile stress in reinforcement. Classified as Type K: Contains anhydrous aluminosulfate burned simultaneously with a portland cement composition, or burned separately when it is to be inter-ground with portland cement clinker or blended with portland cement, calcium sulfate, and free lime. Type M: A mixture of portland cement, calcium aluminate cement, and calcium sulfate. Type S: A portland cement containing a large computed tricalcium aluminate content, modified by an excess of calcium sulfate above usual optimum content.
References in periodicals archive ?
developing Type K expansive cement as its technical director.
Rubin effected a program of applied research and development on expansive cements, and invented methods of testing and measuring restraint of expansion, now used in ASTM C806 Standard Test Method for Restrained Expansion of Expansive Cement Mortar and C878 Standard Test Method for Restrained Expansion of Shrinkage Compensating Concrete.
The newly formed CTS Research Alliance will muster educational leaders to test and expand knowledge of calcium sulfoaluminate (CSA) rapid-hardening and expansive cements.