Nonshrink hydraulic cements have been formulated with various job conditions and requirements in mind. The materials discussed in this article are based mainly on portland cement but they contain expansion-causing agents and sometimes other modifiers.

PATCHING MORTARS AND CONCRETES

Most of these products contain components that cause the mortar or concrete to expand after it has hardened. The expansion is intended to overcome or compensate for the expected drying shrinkage and to maintain a tight bond to the material with which it is in contact.

GROUTS AND ANCHORING CEMENTS

Many grouts and anchoring cements are basically the same kinds of materials as the patching mortars and concretes--materials based on portland cement which derive their expansion from the formation of ettringite or from the release of air from the aggregate into the plastic mix. There is another system that gets its action from releasing gas into the plastic mix; in this case the gas is generated by the reaction of fine aluminum powder in the grout with the cement alkalies.

FIBROUS PATCHING MORTARS AND CONCRETES

Nonshrink mortars that contain steel fibers are for use where high impact strength, great ductility after cracking, and high flexural strength are needed.