Effect of substrate surface roughness on the flexural performance of concrete slabs strengthened with a steel-fiber-reinforced concrete layer

Abstract

In recent years a new strengthening technique that includes the addition of a thin layer made of steel-fiber-reinforced concrete (SFRC) over precast concrete slabs has been introduced. The desired structural performance for this strengthening method can only be achieved if the SFRC overlay and the precast concrete slab behave compositely. In this research, the effects of using different substrate treatments on the composite behavior of precast concrete slabs strengthened by an SFRC overlay are evaluated through experimental tests. In addition, the advantages and disadvantages of a SFRC topping over the conventionally reinforced concrete topping are investigated. The obtained results showed that presence of steel fibers in the concrete of toppings enhanced the deflection at the ultimate load, energy absorption capacity, and failure mode of the strengthened slabs. However, specimens strengthened by SFRC toppings exhibited slightly lower ultimate-load-carrying capacity compared with the conventionally reinforced topping. It was also found that a composite behavior for the strengthened specimens was achievable if the surfaces of substrates were roughened either transversally or longitudinally.