STUDY OF MORTARS AND FERROCEMENT IN TENSION

Abstract

Ferrocement is essentially a composite material, usually consisting of multiple layers of closely-spaced small diameter continuous wire mesh as reinforcement encapsulated in portland cement mortar matrix and as such, the performance of ferrocement will depend upon the properties of both the constituents. The effect of sand/cement ratio, water/cement ratio and grading of sand on compressive and splitting tensile strength of mortar is studied alongwith the tensile response of ferrocement for varying reinforcement content. It is observed that the compressive and splitting tensile strength of mortar can be generally increased by decreasing water/cement ratio and sand/cement ratio and by using coarse sand. Splitting tensile strength of mortar is about 1/15th to 1/12th of its compressive strength. For rich mortar mixes, compressive strength. decreases rapidly with increasing water/cement ratio. The rate of gain of compressive strength at early age is higher for richer mixes with low water/cement ratio as compared to lean mixes. The influence of grading of sand on compressive strength is more significant for lean mixes as compared to rich mixes. Beyond a minimum reinforcement content, the load-elongation curve of ferrocement in tension can be divided into three stages, (1) Initial elastic stage without any cracks, (2) Multiple cracking stage and (3) Crack-widening stage. Ultimate load of ferrocement is nearly equal to the load carrying capacity of reinforcement in loading direction. For identical reinforcement in loading direction, ferrocement specimens with transverse reinforcement show better cracking characteristics as compared to specimens without transverse wires. The number of cracks at failure increases with increasing volume fraction of reinforcement in loading direction and consequently,..average crack-spacing and crack-width decrease. Load at first crack, ultimate load, elongation and toughness increase with increasing volume fraction of reinforcement.