Influence of Wetting and Drying on Swelling Parameters and Structure Performance

Abstract

Structures subjected to distress by expansive soils generally show cracks of various types. These cracks are frequently used as an excuse to adopt nonrealistic decisions in construction practice. It is quite common to opt for structures demolition or expensive retrofitting for just shown cracks and nonsignificant differential settlements. The influence of repeated wetting and drying on the swelling parameters is of concern when justifying such decisions. Expansive formations are inundated by periodic rainfall and storms or other sources. This study is aimed at investigating the geotechnical properties and parameters for an area known of being of serious hazard to buildings and infrastructure projects. This research study is conducted for Al Ghatt clay from Saudi Arabia. Swelling clays supporting superstructure loads of 50, 100, and 200 kPa as contact pressures were subjected to four cycles of wetting and drying. The compressibility and swelling profile were investigated for each stress level and cycle of wetting and drying. The main geotechnical parameters including the swell pressure and the swell potential were measured. The compressibility index and hydraulic conductivity were also computed for all cycles at different level of stresses. Repeated cycles of wetting and drying resulted in reduction of swelling pressure as well as the swell potential by more than four times. Conversely, the variations of the compressibility index were insignificant and the reduction in the hydraulic conductivity was also marginal. A building subjected to serious cracking and movement in the region was monitored over a 1-year period to observe the influence of wet and dry season on the size of the observed cracks. The outcome of this study can encourage engineering communities and contractors to consider observing the structures for a second and third cycle of wetting before choosing to demolish an affected structure.