This report focuses on the properties of treated ground, where the objective of treatment has been the improvement of the load carrying characteristics of the ground. The only ground treatment methods included in this report are those that are used, or are suitable for use, in the UK. The report establishes the best assessments and measurements of engineering properties and performance of treated ground. It also explains how to carry out these assessments and measurements. It will be of direct use to geotechnical specialists and will also be of interest to a wide range of people involved in building and civil engineering projects requiring ground treatment. Guidance is given on good practice in evaluating the effectiveness of treatment. Where ground treatment is used, a successful outcome depends not only on technical factors but also on the use of an appropriate contractual framework within which the treatment is procured and executed. The report should lead to better use of ground treatment techniques and help to improve foundation design and construction on treated ground.This report is published together with C573 A guide to ground treatment (CIRIA, 2002), which provides an accessible introduction to ground improvement.