Geotechnical properties of fresh cement grout—pressure filtration and consolidation tests

Abstract

This technical note examines the effects of removing water from a fresh cement suspension by pressure filtration, which turns the slurry into a material having significant effective stresses; it also clarifies some aspects of the consolidation behaviour of this filtered material. The test series covered: (1) a sulphate-resisting Portland cement (SRC); (2) an ordinary Portland cement (OPC); and (3) a super-fine Portland cement (MFC). They were all normal cements, obtained in 25kg batches. The experiments were like one-dimensional consolidometer tests with top drainage only, but used a slurry as starting material. The usual assumptions for one-dimensional consolidation analysis were made, and the filter cake was also treated as a stiff uniform layer. In the experimental procedure, the grout was mixed for a time in a high-shear disperser, then transferred to a consolidometer tube lubricated with mould release oil, with one layer of tissue and two layers of filter paper placed carefully on top of the grout. A displacement transducer measured the piston movement. Charts and tables are presented for the results of the filtration and consolidation tests. The analysis and data are required for quantitative assessment of construction effects, due to cement grouting or concrete placement in the ground.