Synthesis and evaluation of shrinkage-reducing admixture for cementitious materials

This paper describes a chemical process called ethoxylation to synthesize a shrinkage-reducing admixture (SRA). Using 2-butoxy ethanol and ethylene oxide (EO) or propylene oxide (PO), SRA was synthesized in a laboratory. SRA has a great reducing effect on the surface tension of its solution. Reduced free drying shrinkage (FDS) rate can be measured with the increment of dosage for both mortar and concrete. At 2% dosage, free drying shrinkage can be decreased by 30-40% for both mortar and concrete specimens at 60 days. It also reduces autogenous shrinkage for mortar about 20-30% at 90 days with 2% dosage. Comparing with expansive admixture, SRA performance was better than expansive admixture when no water curing is undertaken.