Unlike traditional sand cement screeds, self-levelling screed is casted with a liquid consistence. This allows an easier application, with no need of trowelling and surface finishing (a light wobbling is enough). As the name says, this screed levels by itself. The fluid rheology of the ix makes this kind of screed particularly suitable to be casted over under floor heating systems.
Self-levelling screed are characterized by a lower thickness than traditional screed (on average 3 cm instead of 5 cm).
Self-levelling screeds can be anhydrite or cement based. In any case their formulation must take into account many possible problematic aspects, in particular the hygrometric shrinkage and thus cracking and curling. For this reason, the largest part of the self-levelling screeds is delivered as dry premixed material, produced by specialized companies, in order to guarantee the correct ratio of all the components, among them chemical additives play a major role.
K.G. Bontira developed PLM-AL2, a mobile plant for self-levelling floor screeds, which is an evolution of the commonly used continuous mixing pumps built up for this kind of application. PLM-AL2 of K.G. Bontira works continuously too. However, the volume of the mixing chamber is much bigger and therefore, the blending of the screed is longer and more accurate. As a primary consequence, the desired consistency is reached with less water and this gives a tremendous advantage to the screed, which has less shrinkage – thus less cracking and curling – and higher mechanical strength.
Levelling compounds and smoothing pastes with low thickness and high mechanical strength can be applied with PLM-AL2 of K.G. Bontira.
Polymer fibres are also often used to improve the quality of the screed, since their effect on the microstructure control the shrinkage, reduces the microcracks and improves the flexural strength. PLM-AL2 of K.G. Bontira features an automatic dosing system for polymeric fibres. The fibres, delivered on rope rolls, can be supplied by K.G. Bontira (Smart Fibers).