Influence of Coarse Aggregate Rubber on the Workability and the Mechanical Strength of Self-Compacting Concrete

Assessment of Special Rubberized Concrete Types Utilizing Portable Non-Destructive Tests

“…On the contrary, the tensile strength showed a performance of around 10% on average compared to the compressive strength. It should be mentioned that the range is usually between 10 and 15% [76,77] The literature should also provide discrepancies in the analysis considering the tensile strength while using crumb rubber for NC [24][25][26][27][28][29], SCC [40,41,[44][45][46][47]49,51,53,[58][59][60]63,64], and RCC [65,[67][68][69]72,73]. The splitting tensile strengths showed a relevant reduction to that available in this study at the level of crumb rubber replacement, whether it was fine or coarse or combined crumb rubber.…”

“…The reduction or enhancement of each strength has its reason. For instance, it was revealed that the ion charges on the surface rubber with the water added during the mixing process could cause repulsion forces, which help in standing still of the workability, and the changes nearly would be related to the crumb rubber aggregate shape whether angular or have a tendency towards flakiness or elongation [60]. Thus, this repulsion forms a thickness of ITZ between the cement matrix and aggregates.…”

“…Thus, this repulsion forms a thickness of ITZ between the cement matrix and aggregates. This consequently would lead to more weak layers and lower bonding between the ingredients of concrete, which is pronounced when the load applied in compression performs premature failure, which is clear in low compressive strength [60], as shown in Figure 11a. The microcrack seems to have occurred between the aggregate and paste, which prematurely failed inside the cube before the fracture occurred.…”

“…The latter explored rubber treatment by soaking it in water for 24 h and in 1 N NaOH solution, stirring it for about 20 min, and then washing it with water before adding it to the SCC mix. Other researchers [54,60,61] concluded that the total aggregate replacement with crumb rubber would perform better by lowering the strength reduction that occurs when adding crumb rubber to the concrete mix, as in the case of fine or coarse aggregate replacement. Similarly, in RCC, most of the researchers [65][66][67][68][69][70][71][72][73][74] studied the replacement of fine aggregate or combined (total aggregate).…”