Linear shrinkage test: justification for its reintroduction as a standard South African test method

Abstract

Several problems with the linear shrinkage test specified in Method A4 of the THM 1 1979 were addressed as part of this investigation in an effort to improve the alleged poor reproducibility of the test and justify its reintroduction into THM 1. A open-sided trough is recommended for the test which, if implemented will reduce the problem of bowing at high plasticity significantly and improve the accuracy of the actual shrinkage measurement. Recommendations are also given regarding the approperiateness of the correction factor for soils of increasing plasticity. The report also highlights the need to adhere rigidly to the test method, especially during the process of drying of the samples. Alternative drying methods may lead to a significantly variation in linear shrinkage results.