Shear Strength of Concrete Beams without Stirrups Made with Recycled Coarse Aggregate

Abstract

Eco-friendly concrete that considers waste material and requires less energy for production is in demand because it produces less carbon dioxide, reduces the consumption of raw material, and can be a cheaper option to conventional concrete. The objectives of this study are to investigate the shear behavior of reinforced concrete beams made with locally produced recycled coarse aggregate from construction demolition waste, study the important parameters that affect the shear strength and ductility, and check the applicability of the available theoretical shear strength predictive equations to recycled concrete. An experimental program that involved the testing of fifteen half-scale beams in shear without stirrups was carried out with a theoretical component. Results of the study showed that recycled concrete beams employing 50% recycled coarse aggregate had on average 27% lower shear strength than corresponding beams made with natural aggregate when tested at a shear span-to-depth ratio equal to 1.15, and almost the same strength as the natural aggregate beams when subjected to a shear span-to-depth ratio equal to 2.5. On the other hand, the average shear strength of beams utilizing 100% recycled aggregate was lower by 5% than the strength of their natural aggregate counterparts, irrespective of the shear span-to-depth ratio. The longitudinal steel reinforcement ratio had less effect on the shear strength provided by recycled concrete beams than on those made with natural aggregate, possibly due to the reduced ability of such concrete to develop strong dowel action. Although the use of higher strength concrete improved the shear strength of recycled aggregate beams, there was no clear correlation between the square-root of the concrete compressive strength and the shear strength provided by the concrete. The theoretical part of the study showed that the ACI 318 code and the strut-and-tie method can be reliably used to predict the shear strength of concrete made with recycled coarse aggregate employed in shallow and deep beams, respectively.

Pervious Concrete Made with Recycled Coarse Aggregate and Reinforced with Date Palm Leaves Fibers

“…The experimental test results demonstrate that the tensile strength of pervious concrete drops from 1.56 MPa when natural aggregate is used to 0.67 MPa when recycled aggregate is used. Although concrete employing recycled aggregate is expected to be weaker in tension when compared with concrete containing natural aggregate, the observed drop is much more drastic when compared with previous studies by the authors [56][57][58][59][60][61] on non-pervious concrete. The inferior quality of the recycled coarse aggregate due to its higher water absorption, lower density, possible content of organic substances, higher level of crushability, and reduced abrasion resistance contributes to lower tensile strength of pervious concrete.…”

“…The tests showed that 100% replacement of the aggregate caused the compressive strength of pervious concrete to reduce by 36%, from 7.08 to 4.53 MPa. Earlier studies by the first two authors [56][57][58][59][60][61] on non-pervious concrete have indicated the full replacement of natural coarse aggregate with recycled aggregate from construction demolition waste obtained from the same source can reduce the compressive strength by an average of just 10-15%. The lack of adequate amount of fine aggregate in pervious concrete increases the importance of the coarse aggregates and the bond between them to the mechanical properties of the concrete.…”

The Structural Behavior of Reinforced Concrete Beams Made with Locally Produced Recycled Aggregate in the UAE

“…This improved result of the R-M-100 mix can be attributed to the rough texture of the RA, which enhances the interlocking action within the concrete. This interlocking effect contributes to an improved tension behavior in concrete containing RA [31]. The presence of such surface characteristics in the RA can create a more efficient stress transfer mechanism, resulting in the observed increase in tensile strength.…”

“…Most of the available research on the shear behavior of structural concrete made with recycled aggregate suggests that beams made with RA concrete possess either just about the same or marginally inferior ultimate shear strength compared to corresponding beams made with NA concrete. Table 2 summarizes some of the related research efforts found in the literature [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”

The Impact of Shear Reinforcement Amount and Arrangement on the Shear Capacity of Shallow RC Beams: An Experimental Study

“…Odero et al [21] tested sixteen concrete beams using RCA and concluded that at 10 mm aggregates, the shear capacity of the specimens was at its highest by 21.5%. Sagheer et al [22] had tested fifteen concrete beams with 50 % RCA for some and 100 % RCA for the others. The specimens with 100 had a 26% increase in their shear capacity compared to the 50 % RCA.…”