Effects of fillers on the properties of cement grouts

Abstract

Cement grout is a mixture utilized for connecting different precast sections, filling voids or sealing joints. The present study reports the suitability of incorporation of fillers such as fine sand and fly ash in cement to develop grouts and evaluation of the flowability and mechanical properties of the prepared grouts. Filler incorporated mixes at low water-cement ratios were not workable. Hence, the workability had to be achieved by addition of chemical admixture, i.e., superplasticizer. In this study, polycarboxylate ether based superplasticizer is added during the mixing process. Different compositions of grouts are prepared for the experimental study. 10% of cement mass is replaced with silica fume in all the grouts whereas up to 50% of cement mass is replaced with fillers in certain mixes and the fresh and hardened state properties are evaluated. Excessive bleeding, grout instability, long setting times and low mechanical strengths are some of the problems associated when the water-cement ratio is increased. Mixes incorporating silica fume only showed poor workability at low water-cement ratios but improved strength compared to other mix types. Grouts incorporating fine sand and fly ash showed poor early age strengths compared to cement grouts containing silica fume only. Also, grouts with fine sand as filler showed improved performance for shrinkage and water absorption over plain cement grouts.