Static strength properties of artificially cemented sands.

摘要

In this thesis, the effects of cementation on a selected local dune sand have been studied under static loading. Stress-strain, strength and general characteristics of artificially cemented sands, were determined under different loading conditions, different cure periods, different cure types and different sample's density. The two cementing agents used were portland cement and calcium carbonate.; Artificially cemented sands were prepared in the laboratory where control over different parameters can be achieved. Unsaturated undrained static triaxial as well as drained static triaxial tests were performed on the artificially cemented sand specimens. Stress-strain and p-q diagrams were drawn and strength parameters (cohesion and angle of internal friction) were determined for all test samples.; The results show that the addition of a cementing agent to a wind-blown sand with uniform size distribution produces material with two components of strength--that due to the cementing agent itself and that due to the frictional component of the sand. Cemented sands distinguish themselves by having a well defined cementation/cohesion intercept while the angle of friction of a cemented sand is similar to that of uncemented sand. The results also show that drying process is essential in cementation development especially when calcium carbonate is used as an agent. The lower the moisture content at testing the higher the peak strength and initial tangent modulus values. Peak strength as well as initial tangent modulus values, increase with increasing cure period, confining pressure, cement content and density. Residual strength values seem to be independent of all parameters except confinement and density.