灌漑・排水システム工学

Performance Evaluation of Cement Grouting by Universal Testing Machine to Improve the Bearing Capacity of Sandy Soil

Abstract

Naveed Khan, Izaz Khan, Aman Ullah, Muhammed Yasir and Shoaib Naseer

The sandy soil of coastal areas of rivers and oceans due to permeable nature and high water table always provide weak foundations for construction purposes. Due to shear failure and excessive settlements, the sandy soil reduces the safe bearing capacity for high rise building and dam construction purposes. Because of these poor soil properties, several methods are reported to enhance the capability of the soil and apply different grouting materials for its improvement. In this study, several tests were applied to investigate the physicochemical properties of sandy soil and to improve their properties such as shear strength, reduction in settlements and increase the bearing capacity. The properties of sandy soil was measured such as size and moisture content by Sieve analysis, in-situ density by sand cone replacement method, specific gravity by using pycnometer. In similar fashion, cement was characterized such as fineness by sieve analysis, standard consistency, initial and final settlement time was measured by vicat apparatus, soundness and specific gravity of cement was checked by Le-chatlier flask. After material characterizations, shear strength and permeability tests were done to investigate the suitability of sandy soil for grouting applications. Normal and shear stress was measured by direct shear stress apparatus and both stresses increases with increase in load. The permeability of sandy soil was measured by constant head permeability and hydraulic conductivity was reported in medium range which is suitable for plate load test. The plate load test was done by Universal Testing Machine (UTM) for sandy soil. The high settlement of sandy soil by applying load revealed the low bearing capacity and grouting was needed. Cement grout was applied in different water cement ratios, such as 7:1 to 4:1 range. At ratio 7:1 (G1) the settlement was higher while applying the load than 4:1 (G4), which has the lesser settlement. However, when the water content was decreased than G4, then the work ability and flow of the grout was much less for applications. It is concluded that G4 is the best combination of cement grout which has least settlement and maximum bearing capacity which can be preferred combination for construction on sandy soils at coastal areas and deserts.