ABSTRACT
Optimizing the composition of polypropylene fibre cementitious composites is proposed. Two parameters of fibres were taken into account in this test: their length and volume content in matrix. Basing on seven points statistical Box design, authors presented the optimization procedure, where both the bending strength and toughness index I5 were the criteria of optimization. This procedure is supported by statistical method of experiment design.
In this test the commercial polypropylene fibres were used and their length and volume changed from 5 mm to 30 mm and 0.1% to 3.0 % of matrix volume, respectively. The matrix was standard cement mortar using in Poland in cement strength testing and concrete with coarse aggregate 2–8 mm.
The results obtained are presented on the graphs in the form of relation: y = f(x 1, x 2), where y was property measured (bending strength or toughness index) and x 1, x 2 were test factors considered (fibre volume and fibre length). Thus the obtained relations show the changes of mechanical properties of composites tested fibre reinforced mortar and concrete as the function two variables.
Basing on analysis of these relations the authors concluded that the optimum composition taking into account both fibre volume and fibre length may be differed in dependence on property considered.
