Strength development in blended cement admixed saline clay

Cement stabilization is extensively used to improve engineering properties of soft saline clays. The effect of salinity, which is modified by geological and climate changes, on the strength development in cement admixed saline clay is investigated in this paper. For a particular curing time and salt content, the strength development in saline clay admixed with cement is governed by the clay-water/cement ratio, wc/C. The strength increases with the decrease of wc/C. The increase in salt content for a particular water content decreases the inter-particle attraction of the clay and the cementation bond strength. Hence, for the same clay-water/cement ratio, the strength of the cement admixed saline clay decreases with increasing salt content. In order to increase strength, and improve the economic and environmental impact, fly ash (FA) and biomass ash (BA) can be used to substitute Portland cement. The influence of FA and BA on the strength development of cement admixed saline clay was investigated with unconfined compressive (UC) test and thermogravimetric (TG) analysis. FA and BA were dispersing materials, increasing the reactive surface of the cement grains, and hence strength increases as well. The clay-water/cement ratio hypothesis was used successfully to analyze and assess the strength development of blended cement admixed saline clay at various salt contents. An addition of 25% ash can replace up to 15.8% of cement.

► Conduct index tests on saline clay samples with different salt contents.
► Explain the role of salt content on strength development in cement admixed saline clay.
► Analyze the strength development using the clay-water/cement ratio hypothesis.
► Develop a generalized strength equation for blended cement admixed non- to low-swelling clays.