The engineering description of chalk: its strength, hardness and density

Abstract

The description of chalk for engineering purposes is reviewed and recommendations are made for a refined method for the field determination of chalk strength, hardness and density. The proposed method incorporates field descriptions, the current CIRIA intact dry density divisions and the strength terms of BS5930:1999. The recommendations arise from work on chalk tunnels where it was found that the previous methods of field assessment gave unreliable results. Specific fieldwork was carried out to develop the proposed system on a wide range of Middle and Upper white chalks in southern England.