Effect of pressure after casting on high strength fibre reinforced mortar

Abstract

This study investigates the effects of applying pressure after casting on the flexural response of high strength fibre reinforced mortar in which up to 5% fibres by volume were premixed. High mortar strength was achieved by reducing mix porosity (low water-cement ratio), adding fly ash and using superplasticisers. Variables included eigth different types of fibre, their volume fraction in the mix, two mortar matrices, two values of pressure after casting, and the casting orientation. It is found that pressure improves the proportional limit and the flexural strength of the composite but may lead to a deterioration in its postcracking response and toughness. Composite moduli of rupture of more than 5000 psi (37 MPa) are observed with steel fibres while highest toughness indices of up to 90 are reported with polypropylene fibres. It is concluded that the application of pressure after casting to improve composite properties is not economically justifiable.