Abstract:
The first section investigated the mechanical properties of concrete utilizing
coarse recycled asphalt pavement (CRAP) as a partial replacement for natural coarse
aggregate at replacement levels of 5, 10, 15, 20, 25, and 30% by weight. The
compressive strength of CRAP concrete was compared to that of natural aggregate
concrete, revealing a reduction in compressive strength ranging from approximately
3% to 22%. Furthermore, a predictive equation for the compressive strength of CRAP
concrete was successfully developed, which can estimate the strength within
acceptable engineering tolerances, achieving an R-Square value of 0.99. This section
also examined the impact of hooked-end steel fiber reinforcement at volumes of 0.25,
0.50, 0.75, and 1.00% on the concrete's mechanical properties. The inclusion of steel
fibers resulted in an increase in compressive strength by approximately 4.5% to 13.9%,
splitting tensile strength by about 16.6% to 57.5%, and flexural strength by around
13.6% to 66.3%.
The second section focused on the flexural behavior and failure characteristics
of precast reinforced concrete (RC) beams containing recycled asphalt pavement and
reinforced with steel fibers. Test results demonstrated that the beam specimens
exhibited linear elastic behavior initially, with the concrete and steel reinforcement
jointly resisting the load until the applied force reached about 40% to 50% of the
maximum load. The beam then entered a second stage where the slope of the load
deflection curve decreased slightly due to increased and expanded cracking in the
concrete tension zone and the yielding of the tensile reinforcement. Finally, the
cracking continued to grow until the beam failed. A comparison of the beam capacity
with the ACI reinforced concrete beam design equations confirmed that the ACI design
equations accurately predicted the strength of both the reference RC beams and the
RC beams containing recycled asphalt pavement. Moreover, the ACI design equations
conservatively predicted the load-carrying capacity of the steel fiber-reinforced RC
beams with recycled asphalt pavement, providing an increased safety margin of 5% to
6%.