Modification of AA Binder Matrix with the Use of PP Fibres – Strength Investigations

Abstract

The alkali-activated (AA) binders are assumed to be more ecological than ordinary Portland cement (OPC) binders, because of lower energy requisition and lower CO2 emissions during the production processes. The purpose of using polypropylene(PP) fibres in traditional concrete, geopolymers and mortars is to improve strength properties by inhibiting the growth of cracks that usually occur due to shrinkage, as well as improving the mechanical properties. This paper presents laboratory research into the fibre reinforcement impact on the strength properties of an AA binder made of fly ash suspension. In addition to the suspension, which is a waste product from the coal power plant, recycled ground glass and metakaolin were used as the precursors. The chemical activator of the geopolimerisation reaction was prepared using sodium hydroxide and sodium silicate. Five different sets of the prism samples 40x40x160 mm were made (with different PP fibres ratio, from 0% to 2% by weight) and then the flexural and compressive strength tests were performed. The addition of polypropylene fibres increased the bending strength, which produced the beneficial effect of reducing crack propagation in cases of tensile stress occurrence.
 Keywords: alkali-activated binders, geopolymers, polypropylene fibres, fly ash suspension, bending strength