EFFECT OF MINERAL ADDITIONS ON THE DURABILITY OF REPAIR MORTARS IN HOT CLIMATE

Abstract

The aim of this work is to study the effect of supplementary cementitious materials (SCMs) as marble powder (MP) on the performance of self-compacting repair mortars (SCRMs) reinforced with polypropylene fibres (PPF). Two series of mortars (PPF and PPF+ MP) were prepared and evaluated. Previously, an optimisation of fibre dosage in terms of fresh and hardened states was assessed, then incorporating MP as cement replacement. The evaluation of repair mortars was carried out on rheological properties (slump flow, flow time, yield stress and plastic viscosity), fresh density and mechanical strength (compressive and flexural strength). In addition to elasticity modulus), thermal conductivity, shrinkage and durability properties (mercury intrusion porosity) and capillary absorption. Moreover, the effect of hot-dry climate was evaluated on adhesion strength between repair mortar and substrate concrete. Three bond strength test methods were assessed on composite specimens (repair mortar/substrate material) conserved in two conditions (standard climate T=20±2°C, RH= 30% and real hot climate T=40±5°C, RH= 10%). The obtained results revealed that, 0.06% of PPF is the optimum dosage with the highest compressive strength and good flexural strength. The introduction of MP decreases both plastic viscosity and yield stress. The combined use of PPF and MP showed good mechanical properties of SCRM which fulfilling the requirements of class R4 materials for structural repair products. Moreover, incorporating MP to fibre reinforced repair mortar increases its thermal conductivity compared to control mortar and reduces considerably porosity rate. On the other side, elasticity modulus has decreased with the increment of MP content however, a good correlation is attained between elasticity modulus and compressive strength. Adhesion test by slant shear method indicated that 15% of MP is the optimum dosage which provides 20% of gain in adhesion strength.