ABSTRACT
Pastes made from conventional cements preserve their plasticity for several hours before setting and hardening. Such a plastic stage is necessary so that it is possible to produce a concrete/mortar mix of the desired consistency, transport it to the place where it is to be applied, and compact it after placing. In some special applications, however, cements with very short setting times are required. Examples of such applications are various repair works (repairs of pavements, for example) and emergency measures (such as plugging of leaks to prevent leakage of water or other liquids). Obviously, the use of such rapid-setting mixes requires particularly fast mixing, placing, and compacting. Mixes that set almost instantaneously cannot be used in the traditional way, and must be applied by spraying. The use of fast-setting cements in spraying applications makes it possible to build up thick layers of material in a single pass even on vertical backgrounds, thus increasing the effectiveness of this technology.
