Chemically stabilised sandstone sub-base: A comparative investigation of the relationship between California bearing ratios of top and bottom sample surfaces

There are limited previous investigations on the contributory factors to the relationship between California bearing ratios (CBR) of top and bottom surfaces of chemically stabilised sandstone samples. The aim of this paper is to consider three of these factors: gradation, stabilisation type and soaking condition. Three sandstone gradations of different gravel-to-sand ratios were considered: 2.1, 1.2 and 0.4. Four stabilisation types were inspected: unstabilised, cement-stabilised, polymer-stabilised and polymer-cement stabilised. Two soaking conditions were examined: unsoaked and 4-day soaked. The conclusions from the investigation were: (1) CBR values of samples increased with increasing G:S ratios, (2) cement stabilisation provided the greatest CBR values and this was followed by polymer-cement and lastly, polymer, (3) bottom surfaces of unsoaked samples generally had greater CBR values than those of top surfaces, and the opposite was true for soaked samples and (4) bottom surfaces of the samples were more sensitive to soaking than top surfaces.