Characterization of Concrete with Red Mud Coarse Aggregate under Direct Shear Tests

This experimental work realized a series of direct shear tests on monolithic notched concrete blocks. The aim was to evaluate the performance of concrete with red mud coarse aggregate in the pure shear state. Its performance was compared with the shear strength results of mortar, gravel, and pebble concrete block series. In addition, the influence of the maximum size of the coarse aggregate, in different distribution ranges, on the gain in maximum strength was analyzed. The results showed that synthetic coarse aggregate had the best performance of all in terms of the concrete’s compressive strength, regardless of the size of the aggregate; however, the distribution with a trend toward larger sizes provided higher increases, as much as quadrupling the strength capacity compared to the mortar block. Thus, the work has demonstrated that synthetic aggregates can be viable in structural concrete applications, such as in concrete beams and slabs subjected to shear stresses, as well as being a sustainable alternative for mitigating environmental pollution caused by the accumulation of mining waste.