Shear Performance of Concrete Beams with a Maximum Size of Recycled Concrete Aggregate

Abstract

e use of concrete mixes with recycled materials has gained traction in research communities. However, the major drawback of the recycled concrete aggregate (RCA) has been the contribution of the cement paste mortar attached to the surface. e quantity of surface-attached mortar on the virgin aggregate dominates and de nes the shear performance of concrete beams. Concrete shear failure is usually abrupt and catastrophic, especially in concrete beams without shear reinforcement. e e ectiveness of the maximum size of RCA for the performance of untreated and treated with pozzolanic cement and rice husk ash (RHA) slurry was investigated. A total of sixteen ( 16) beams containing RCA of four (4) maximum sizes, 10, 14, 20, and 25 mm, were prepared and tested after 28 days. e beams were loaded in shear using shear span-depth ratios of 1.25 and 2.50. e results showed that the shear strength of the beams increases as the aggregate size increases to a maximum size of 20 mm, beyond which the shear strength reduces. It was attributed to the attached mortar, which increased as the size of the aggregate increased, creating a weak zone for shear failure in the concrete. In addition, RCA pretreatment using slurry-containing cement and RHA strengthened the attached mortar on the aggregate surface. It resulted in a dense and more compact aggregate that slightly improved the shear strength by about 2.2% for beams containing 20 mm RCA size. e ultimate shear strength of the experimental work in the study was predicted using eight (8) selected models from the literature. Models that account for the aggregate size and shear span to depth ratio resulted in shear strength ratios of 1.

Effect of Treated/Untreated Recycled Aggregate Concrete: Structural Behavior of RC Beams

“…Their surfaces were then coated for an hour with sodium metasilicate pentahydrate solution. B. Ordo et al [186] used the application to structural concrete beams without shear stirrups, which will be guided by the pozzolanic preparation with slurry-containing cement and RHA for the ideal coarse RAC size. This work also suggests a surface treatment mechanism for RACs use a targeted strategy to improve the physical and mechanical characteristics of the aggregate to enhance aggregate performance in beams.…”

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

“…The usage of recycled concrete aggregates has been used in concrete members for the last several years, and its effect on the shear strength of the concrete beams has been investigated by several research teams lately. 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.…”

Effect of Concrete Strength on Shear Capacity of Reinforced High-Strength Concrete Continuous Beams without Web Reinforcements

“…(M/ Vd) still has physical signifcance at any cross-section of a beam. In addition, Brian et al [9] showed that regardless of the kind of the coarse aggregate material employed, the shear span-to-depth ratio was found to signifcantly infuence the shear strength of beams. Because continuous beams constitute the majority of the actual construction, understanding the efect of continuity on shear behavior is critical.…”

“…(9) Te values for the ACI equation became less conservative as a/d increased; the fexural moment might have had something to do with this.…”