Mechanical properties of steel fibre reinforced and rubberised cement-based mortars

Previous studies demonstrated that crack cutting bonded cement-based repairs is highly detrimental to the durability of such applications. Laboratory tests and field experience showed that fibre reinforcement allowing the control of the crack opening and assuring the structural continuity is a solution to enhance the durability of bonded cement-based repairs. In other respect, recent work pointed out that the use of rubber aggregates obtained from grinding end-of-life tyres is a suitable solution to improve the strain capacity of cement-based materials. The present contribution focuses on the synergetic effect of rubber aggregate incorporation and of fibre reinforcement from the point of view of the use of the composite in the repair work application.Effects of fibre reinforcement, of rubber aggregates incorporation and of their association are evaluated by comparing the mechanical response of the cementitious mortars in which they are used to the one of the control mortar. Fibre reinforced and/or rubberised cement-based mortar were cast using 20% and 30% by volume of rubber aggregates replacing mineral aggregates. To control the crack as soon as possible, a type of high bond steel fibre was selected in this study and contents of 20, 30, 40kg/m3 have been used. Direct tensile tests were firstly conducted to obtain the tensile strength, the straining capacity and the residual post peak behaviour. Compressive strength and Young’s modulus were determined from compressive tests. Results showed that despite rubber incorporation was detrimental to the material strength (compressive and tensile strengths) and reduced the modulus of elasticity, the strain capacity was enhanced. Results obtained on steel fibre reinforced and rubberised cement-based mortars (SFRRM) pointed out a positive synergetic effect: it is noted that one can make profitable the effects of rubber aggregates (high strain capacity) and those resulting from the fibre reinforcement (significant residual post peak strength) to get an interesting behaviour when resistance to cracking is a priority.