Rapid field evaluation of the strength of cement-stabilized clayey soil

This paper presents an investigation into the hardness and unconfined compressive strength (UCS) of cement-stabilized Shanghai clay. Various specimens with different cement content and curing time were made in order to conduct hardness tests and unconfined compression tests. The Shore-A durometer was used in a pioneer manner to measure the hardness of stabilized clay. Hardness tests suggest that the measured values of degree of hardness ranged from 1 to 87 DH, and the unconfined compression tests showed that the measured UCS varied from 56 to 1,061 kPa. Test results indicate that the average degree of hardness decreases dramatically with an increase in the clay-water/cement ratio. It is shown that the relationship between the degree of hardness and the curing time is approximately linear in the semi-logarithmic plot. An exponential equation is proposed to express the unique relationship between the UCS (qu) and the ratio of degree of hardness (S/Sr) by regression analysis. The expected prediction range of UCS using the Shore-A durometer was calculated to be between 0.04 and 1.79 MPa. The exponential equation proposed in this study may be used to produce a quick prediction of UCS by measuring the hardness of samples in the field.