Effect of superplasticiser type on the properties of cement grouts

The use of superplasticisers in microfine or regular cement-based grouts has become of vital importance in advanced professional grouting practices. These superplasticisers play an important role in the production of more durable grouts with improved rheological characteristics. This paper presents a laboratory study of the effects of a new-generation polycarboxylate superplasticiser on the rheological properties, mechanical strength, final setting time and bleeding of cement grouts in comparison to that of a polynaphthalene superplasticiser. The experiments are conducted using different superplasticiser dosages with cement grouts proportioned with a water-to-cement ratio of 0·33, 0·4 or 0·5. The results show that grouts with polycarboxylate superplasticiser have higher viscosity, slightly increased bleeding and longer setting times compared with the polynaphthalene superplasticiser admixture. However, the polycarboxylate superplasticiser improves the final strength, especially for grouts with a water-to-cement ratio of 0·4 and 0·5, and decreases the yield stress.