Abstract
Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.
Highlights
Construction and demolition waste (CDW) resulting from the demolition of concrete structures that reach the end of their service life has a detrimental impact on the environment [1]
The shear behavior of the tested deep beams is evaluated based on the shear load–deflection response, shear cracking load, shear capacity, crack pattern, failure mode, and strain measurements
Specimens BR0-SF0 and BR100-SF0, without traditional shear reinforcement, exhibited a load decay at the onset of shear cracking followed by a significant change in slope of the deflection response
Summary
Construction and demolition waste (CDW) resulting from the demolition of concrete structures that reach the end of their service life has a detrimental impact on the environment [1]. Concrete mixtures made with RCAs, generally, possess inferior mechanical properties relative to those of NAs [2,3,4]. The effect of RCA replacement on the shear response of large-scale reinforced concrete (RC) beams is uncertain, since some researchers report an inferior shear behavior for RCA-based beams relative to that of NA-based counterparts [5,6,7,8,9], while others reported an insignificant variation in the shear response of NA- and RCA-based beams [10,11,12,13]. Arezoumandi et al [5] reported a 12% reduction in the shear strength of beams with a shear span-to-effective depth ratio (a/d) of 3 and a 100% RCA replacement percentage compared to that of their NA-based counterparts. Rahal and Alrefaei [6] reported shear strength reductions in the range of 13 to 18%
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