The current study examines the potential of lignosulfonate to enhance the engineering behavior of two locally available expansive soils. The expansive soils were collected from Vijayawada and Amaravathi, located in the Capital Region of Andhra Pradesh, India. The soils were treated with four different percentages (0.5, 1, 2, and 4) of lignosulfonate and were allowed to interact for 7 and 28 days. A series of laboratory tests such as unconfined compressive strength, cation exchange capacity and scanning electron microscopy were carried out on the soil specimens. The results indicated that lignosulfonate has significant influence on the strength behavior of expansive soils. The amount of fines content present in soils defines the optimum percentage of lignosulfonate. Lignosulfonate treatment resulted in reduced negative surface charge of soils and formation of Polymer chain microstructure along with flocculated or aggregated particle microstructure, which may attribute to the enhanced strength of the expansive soils.

Increasing number of failures of industrial structures due to distress caused by acid contamination of foundation soils prompted the present study. This study examines the effect of highly concentrated inorganic acids on the swelling and compressibility characteristics of commercially available bentonite and kaolin clay. Two concentrations of sulphuric acid and phosphoric acid are used as pore fluids. Experimental results showed that bentonite specimens contaminated with both acids exhibited significantly lower swelling and compressions than uncontaminated bentonite. Decrease in double layer due to replacement of sodium cations by hydrogen ions is responsible for lower swelling and compressions. On the other hand, kaolin clay exhibited higher swelling with both acids than uncontaminated kaolin clay. However, compressibility marginally increased with both sulphuric acid and phosphoric acid. Formation of flocculant fabric along with mineral dissolution is responsible for deviations in compressibility behaviour of contaminated kaolin clay. The structural alteration due to acid contamination was examined by FT-IR spectroscopy.

In recent years, permafrost warming has adversely affected the performance of infrastructure projects in northern Canada. The common construction practice in these permafrost-underlain areas is to use the pile foundation for building and infrastructure rather than using shallow foundations. Thus, the influence of warming permafrost on the loading capacity of pile foundations is critical for evaluating forthcoming changes under a warming climate. The present study was performed to assess the influence of temperature and loading rate on the adfreeze strength of piles in permafrost soil. A series of uniaxial compressive tests on wooden piles drilled into frozen soil were carried out at various temperatures, mimicking the conditions in warming permafrost. The results demonstrated that an increase in strain rate led to an increase in the adfreeze strength of piles. Moreover, the wooden piles exhibited peak adfreeze strength at a displacement of less than 2 mm for most temperature and deformation rate combinations. Interestingly, although the adfreeze strength of piles increased as temperatures cooled below −1°C, a transition phase between −3°C and −4.5°C was observed in which the adfreeze strength decreased. It could be noted that failure occurred in the wooden piles at temperatures colder than −5°C rather than frozen soil failure at these temperatures. These variations in the adfreeze strength were related to soil temperature, unfrozen water content, and the adhesive bonds at the interface between the frozen soil and pile.