New Repair Material for Ordinary Concrete Substrates: Investigating Self-Compacting Sand Concrete and Its Interaction with Roughness of the Substrate Surface

This experimental investigation studied the development and use of a new self-compacting sand concrete (SCSC) to perform repairs on ordinary concrete (OC) substrates. This type of concrete should have the following characteristics: excellent fluidity, optimum stability, and acceptable bond strength. In addition, a new pouring method was used for the application of the repair layers. For this, nine SCSC compositions were tested for slump flow using an Abrams cone, passing ability by the L-box test, segregation resistance by the screen stability test, and compressive strength. The results obtained from these tests were then employed for selecting the best composition to use as a repair material. In addition, the volume of permeable pore and water absorption was determined by immersion tests. The compressive strength tests were carried out at three different ages, i.e., 7, 28, and 90 days, for the purpose of determining the physical and mechanical characteristics of ordinary concrete (OC) and those of SCSC, separately. The bond strength between the substrate (OC) and the repair concrete (SCSC) was evaluated by performing two tests: a tensile splitting test (indirect tension test) and a concrete pull-off test (direct tensile test), which was also used for the evaluation of the tensile strength of the concrete substrate (OC) and that of the repair concrete (SCSC). The resulting bond strength values showed that it is indeed possible to use SCSC as a repair material in thin and narrow places, and even those having complex geometries.