An experiential investigation on the compressibility behavior of cement-treated Indian peat

Abstract

The rapid population growth and urbanization all over India have created a need for the development of infrastructure which ultimately increases the demand even to utilize the most problematic peats also. Peat is known for its poor load-bearing capacity and high compressibility traits, so any construction undertaken without taking due account of its properties may lead to dreadful consequences. In India, the study in context to peat has been done in a very limited way and which consists mainly of highlighting the zonal occurrence and to some extent evaluating its basic properties only. This paper addresses the efficacy of cement usage on the compressibility behavior of Indian peat. The assessment of the compressibility and consolidation properties of peat treated with different percentages of cement (5, 10, and 15% by weight of dry peat) and curing periods (0 and 14 days) is investigated through one-dimensional consolidation test. Peats collected were of four different ranges of organic content variation (20–76%) covering three different states in the North Eastern Region of India to finally comprehend the effect of varying organic matter in the process of treatment. The laboratory investigation reveals that the Indian peats undergo high compressibility (cc~1.43–3.72), very low rate of consolidation (cv~0.15–0.78 × 10-8 m2/sec), and large creep behavior (cα~0.02–0.07). However, the optimistic outcome observed after cement treatment is the decrease in the compression index (cc), coefficient of compressibility (av), coefficient of volume compressibility (mv), and increase in the coefficient of consolidation (cv). The pre-consolidation pressure (σ/p) is also increased with the percentage of cement content. Further, secondary compression (cα) measured at high stress level is found to be decreased with increasing cement content and finally becomes negligible. The effect of curing days brings a further conducive change in the compressibility and consolidation characteristics of cement-treated peat. Further, the presence of the high organic matter hinders the reaction process between peat and cement, thus affecting the rate of hardening process and eventually the overall improvement. Finally, the test results are complemented by pH, electric conductivity (EC), and Fourier transform infrared (FTIR) spectroscopy analyses, which provide insight into the mechanism involved between peat and cement. The increased loss of mass that occurs after cement addition, studied through thermo gravimetric analysis (TGA), indicates the formation of new cementitious materials that are responsible for the overall improvement of Indian peat. Since in India, this kind of study is totally new thus it will help engineers practically to handle peat of this region in a far better way eventually bringing a sort of understanding over the construction-allied issues beforehand.