Mechanisms of long-term decay of tension stiffening

Details of an extensive collaborative project to study tension stiffening have been recently published in a number of papers. Among other factors, the project investigated the loss of tension stiffening with time. It has been concluded that the reduction of tension stiffening to a constant long-term value is fairly rapid, being complete in 10–30 days. This paper explores the mechanisms that may operate to cause the reduction of tension stiffening with time. It is concluded that the loss is mainly attributed to cumulative damage resulting from either the formation of additional surface cracks or the formation or extension of internal cracks. It would appear that the final tension stiffening is only minimally dependent on concrete strength.