On the influence on the efficiency of anti-shrinkage additives superplasticizer

Abstract

Cement paste shrinkage and influence of the shrink-resistant additive Estrifan Additive RCL on this process were studied, both when the latter one was used independently, and in a combination with the superplasticizer Muraplast FK48, and powdery fillers - fly ash and silica fume Reftinskaya TPP ISU-85. It has been revealed that cement shrinkage in the presence of this additive is reduced regardless of the presence or absence of mineral microfillers. Moreover, these fillers have no impact on shrinkage. When the content of additives is more than 2% at the initial stage of hardening expansion was observed. The expansion period is getting longer, and the expansion deformation value is becoming higher with the increased dosage of the additive. Presence of the superplasticizer FK48 strengthens the effect of the initial expansion caused by the RCL additive, and also reduces shrinkable deformation in spite of the fact that this additive increases shrinkage of a cement stone when used independently. It has been established that the expansion is caused by the additive influencing the chemical processes of hydration, allegedly influencing the growth of crystals calcium gidrosulfoalyuminat. The expansion partially or completely compensates shrinkage which develops generally due to removal of moisture. The superplasticizer FK 48 slows down water evaporation and, thereby, increases efficiency of the RCL additive action. However, under the equal condition of moisture losses, the ability of the FK48 additive to slow down water evaporation loses its value and action of this additive is negative.

Keywords

• cement stone
• air shrinkage
• autogenous shrinkage
• expansion
• additives
• fillers
• synergy
• strength