Effect of Superplasticizer Type and Dosage on Early-age Shrinkage of Portland Cement and Rice Husk Ash Pastes

摘要

In this work, the effect of superplasticizer type and dosage on early-age shrinkage of ordinary Portland cement (OPC) and rice husk ash paste (RHA) was investigated. The OPC and RHA pastes with a water/binder materials ratio (W/B) by weight of 0.22 and various dosages of polycarboxylate ether-based superplasticizers (PCE) and sulphonated naphthalene formaldehyde condensates (SNF) were investigated. RHA was partially substituted of 0%, 10% and 20% by weight of OPC. Volumetric shrinkages of the pastes at the first 72 hours of hydration have been found to range from 0.28 to 12.26 mm~3/g and from 0.20 to 9.04 mm~3/g of binder materials for SNF-based and PCE-based superplasticizers, respectively. The PCE-based superplasticizer can decrease an increase in shrinkage of the OPC and RHA pastes higher than those of containing the SNF-based superplasticizer.