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Residual soils are produced from weathering of rocks and commonly found in tropical humid areas. The geotechnical properties of residual soils are a function of the parent rock, the degree of weathering, and climate which vary from region to region. A thorough quantification of the geotechnical characteristics of residual soils is required for a safe and economic structure design. This study attempts to summarize a series of important geotechnical properties of a Malaysian granitic residual soil grade V which determine the suitability and ability of the soil for construction including particles size distribution, specific gravity, plastic index, soil water characteristic curve, and shear strength. The findings were compared with geotechnical properties of other residual soils which were reported previously. The results showed weathering grade and the percentage of fine particles are the two important factors in controlling the geotechnical properties of residual soils.

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The removal of natural organic matter (NOM) using a continuous flow fixed bed granular activated carbon (GAC) column was studied and the results were then fitted with the Adams-Bohart, Bed-Depth-Service-Time and Clarks models. The GAC, KI-6070 and KI-8085 used in the study had external surface areas of 277 m2/g and 547 m2/g, respectively. Adsorption of NOM by the GAC was complex and involved more than one rate-limiting step. The critical bed depths for KI-6070 and KI-8085 were 0.24 m and 0.3 m, respectively. The Clark model was more effective in simulating the absorbent breakthrough process as compared to the Adams-Bohart model. The lower empty bed contact time (EBCT) i.e. 15 minutes gave a better fit to the Clark Model as compared to EBCT of 20 and 30 minutes.

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The shear strength of an unsaturated soil is controlled by two variables; net stress and suction. The conventional triaxial machine which is used for obtaining the shear strength of saturated soils cannot be used for unsaturated soil conditions due to weakness in suction control during the consolidation and shearing stages. In the view of this, the standard triaxial apparatus needs to modify and develop for unsaturated conditions. The main aim of this paper is devoted to give a description of current methods and techniques using triaxial apparatus for obtaining data to interpret the accurate shear strength behavior of unsaturated soils. In additional some of the key aspects related to air diffusion and volume change measurement are highlighted.