ABSTRACT
The performance of concretes reinforced with low contents of polypropylene fibres is expected to be improved by reducing sensitivity to cracking. The concepts of an improved method for measuring the cracking sensitivity using a modified ring test for restrained shrinkage evaluation is described. The test was used to study the influence of polypropylene fibre content and type on the cracking sensitivity of poorly cured concrete, either fresh concrete without any curing or concretes cured for 2 days prior to being exposed to drying conditions. The fibres were more effective in the case of the fresh concrete. Fibres of improved structure were required to provide reduced cracking sensitivity for the 2 days cured concrete.
