Performance of Repair Mortar with Natural Fibers

Abstract

ABSTRACTConcrete is the most used material in the world after water because of its good mechanical characteristics and its reasonable cost. However, reinforced concrete structures can be damaged by corrosion or other chemical attacks and require repair and maintenance. The repair materials need to satisfy some mechanical and physico-chemical characteristics. Ready-made repair mortars are widely used. However, they are quite expensive, generally imported and they frequently incorporate low volume of synthetic fibers. This paper reports an experimental investigation designing an environmental friendly repair mortar made of local mineral addition (natural pozzolan (PN) and slag (SL)) and local natural fibers. The natural fibers used are Alfa fibers and date palm tree fibers at a volume ratio of 0.75%. The physical and mechanical properties studied are compressive strength, bending strength, total shrinkage and bond strength by slant shear and pull-off tests. The durability of the mortar was assessed by water capillary absorption. The results are compared to those of a reference mortar. The results showed that the substitution of cement by slag and natural pozzolan lead to a decrease in shrinkage (at 28 days of age). The use of date palm and alfa fibers improves the bending strength but reduces compressive strength. According to the results of the pull-off tests, only mortars containing slag meet the minimum value (1.5 MPa) required by EN1504-3. The types of failures observed for most composites show that they can be successfully applied with 20 mm thick layers.