Effect of low modulus sisal and polypropylene fibre on the free and restrained shrinkage of mortars at early age

This is the first part of a two-part paper involving the study of the free plastic shrinkage and cracking sensitivity during early drying of mortars r einforced with low modulus sisal, coconut, and polypropylene fibres. This w ork also evaluates the effectiveness of crack control at early ages on the corrosion of steel bars, which are sensitive to the presence of cracks in t he matrix. The performance of cement-based material in the fresh state is e xpected to improve by reducing the free shrinkage and sensitivity to cracki ng due to the addition of a low content of polypropylene fibres. This paper discusses the effectiveness of the use of natural sisal fibres for control ling the free and restrained early age shrinkage of mortars and compares th eir performance with that of polypropylene fibre. In addition, a prediction model for the free plastic shrinkage of natural sisal fibre reinforced mor tars is proposed based on a factorial design of experiment. (C) 1999 Elsevi er Science Ltd. All rights reserved.