Introduction of Cement-based Self-leveling Screed Surface Layer
keywords
Cement-based Self-leveling Screed Surface Layer, retarder, ettringite, anhydrite, redispersible latex powder, antisettling agent
Overview
Cement-based Self-leveling Screed is a kind of cement base made of silicate cement, active mother material stimulator.
Cement-based Self-leveling Screed composed of a variety of active components of dry mixed type of powder materials, mixing water can be used. With a little scraper, you can get a high flat base surface. It has the advantages of fast hardening speed and fast construction.
Cement-based Self-leveling Screed Surface Layer is a special cement, OPC, gypsum as the main cementing material, adding filler and various admixtures made of new ground leveling decorative materials, can quickly, efficiently leveling the ground, and has excellent decorative effect, has good leveling, high early strength, easy laying, fast construction speed, short construction period, etc.
Mechanism of shrinkage and cracking of mortar
Cement-based Self-leveling Screed Surface Layer is usually large area construction, high surface volume ratio caused by evaporation and severe hydration reaction will cause significant chemical contraction to make it easy to produce shrinkage and cracking.
For the self-leveling mortar surface of the cement foundation layer with a thickness greater than 10mm, the shrinkage stress is the most important factor leading to its early cracking. As the strain of contraction (including self-contraction and dry contraction) increases, the foundation constraint on the ground cannot deform freely, thus forming the contraction stress distributed along its length. When the shrinkage tensile stress exceeds the tensile strength of the cement base leveling mortar, the self-leveling mortar will crack.
Therefore, controlling the shrinkage strain of cement foundation layer will be beneficial to reduce the cracking risk of autogenous leveling mortar.
Major factors
Ettringite is the main factor affecting the strength and volume change of cement foundation layer;
Gypsum is an important cementing material and expansion component of cement foundation leveling mortar in the cement foundation layer. Provide CaSO4 and cement reaction in the cement foundation leveling layer to offset the shrinkage of cement leveling mortar.
Retarder
Tartartaric acid is a commonly used slow coagulation component in cement base surface layer. The mixing amount of tartaric acid is an important additive to adjust the construction time and setting time of cement base surface layer.
Ingredients
Main materials: OPC, Calcium aluminum cement, quartz sand;
Additives: redispersible latex powder, polycarboxylate superplasticizer, defoaming agent, precipitation agent, early strength agent, tartaric acid, antisettling agent, anhydrite, coarse whiting, etc.
