Performance evaluation of structural concrete using controlled quality coarse and fine recycled concrete aggregate

2015 ◽  
Vol 61 ◽  
pp. 36-43 ◽  
Author(s):  
Abdurrahmaan Lotfy ◽  
Mahmoud Al-Fayez
Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4612
Author(s):  
Dong Viet Phuong Tran ◽  
Abbas Allawi ◽  
Amjad Albayati ◽  
Thi Nguyen Cao ◽  
Ayman El-Zohairy ◽  
...  

This paper reports an evaluation of the properties of medium-quality concrete incorporating recycled coarse aggregate (RCA). Concrete specimens were prepared with various percentages of the RCA (25%, 50%, 75%, and 100%). The workability, mechanical properties, and durability in terms of abrasion of cured concrete were examined at different ages. The results reveal insignificant differences between the recycled concrete (RC) and reference concrete in terms of the mechanical and durability-related measurements. Meanwhile, the workability of the RC reduced vastly since the replacement of the RCA reached 75% and 100%. The ultrasound pulse velocity (UPV) results greatly depend on the porosity of concrete and the RC exhibited higher porosity than that of the reference concrete, particularly at the transition zone between the RCA and the new paste. Therefore, the sound transmission in the RC required longer times than that in the reference concrete. Moreover, a predictive equation relating the compressive strength to the UPV was developed.


2020 ◽  
Vol 220 ◽  
pp. 01098
Author(s):  
Mohammad Tabrez Ali ◽  
Ibadur Rahman ◽  
Nirendra Dev ◽  
Priyanka Singh

When sustainability has become a primary measure of the selection of the building materials in the construction industry over the past decades, researchers all around the world have been looking upon for alternatives to reduce the overall environmental impact of the construction materials while not compromising the strength and durability. The factors like manufacturing, reusability, recyclability, disposal etc, are the criteria of utmost attention affecting the overall life cycle impact of the construction materials. In this prospect the Recycled Concrete Aggregate (RCA) has shown up as an exceptionally viable contender for the manufacturing of concrete with several environmental benefits over the Natural Aggregate (NA) and has already been identified by industry and several government agencies across the globe. The efficient material use of RCA can potentially deliver an inferior though competent concrete in comparison to the NA while averring the criteria of sustenance. The present study delves into the calculation of the proportion of the RCA in a mix design for achieving maximum compressive strength. The experimental setup constituted the casting of concrete cubes of control mix design of M40 grade with proportions of RCA varying from 0-100 percent spread over a space of 10% with NA which were later put to tests. The thorough investigation on the casted concrete cubes lead to the conclusion that the mix design with 50% proportion of RCA in addition to 50% proportion of NA delivered the maximum compressive strength, an average value of 8.23% higher than that of the normal concrete and the highest Rebound Number, an average value of 53.92 for the M40 grade concrete thereby showcasing the feasibility of producing structural concrete with RCA. The results are asserted to be governed by the better bonding between the RCA and NA and due to the significant increase in the water retention capacity by the provision of RCA in the mix.


2022 ◽  
Vol 315 ◽  
pp. 125384
Author(s):  
Helena Lunkes Strieder ◽  
Vanessa Fátima Pasa Dutra ◽  
Ângela Gaio Graeff ◽  
Washington Peres Núñez ◽  
Felipe Raul Meert Merten

Author(s):  
Xijun Shi ◽  
Anol Mukhopadhyay ◽  
Dan Zollinger

To overcome the challenges associated with natural aggregate shortage and the disposal of construction and demolition waste, recycled concrete aggregate (RCA) has been increasingly used in Portland cement concrete (PCC) pavement as a virgin aggregate replacement. The work in this study involved conducting a performance evaluation of the existing RCA-PCC pavements in Oklahoma from different aspects, including: laboratory determination of mechanical properties; a petrographic examination of the concrete; a field evaluation using a falling weight deflectometer (FWD) testing; and distress surveys to assess pavement behavior. The laboratory testing of the field cores confirmed that the addition of RCA into PCC causes a reduction in the modulus of elasticity and tensile strength; the reclaimed mortar was found to be the primary weak zone through which cracks pass. The surface condition survey data and analysis of the FWD results match each other, indicating that the RCA joined plain concrete pavement (JPCP) section exhibited lower performance compared with the control JPCP section. But this trend was not as definitive for continuously reinforced concrete pavement (CRCP). The relatively good performance of the RCA CRCP results from the section being rested on a stronger asphalt concrete base layer. Additionally, the inherent stiffness fundamental to the behavior of CRCP provides a superior level of protection of the base from erosion damage compared with a jointed pavement. The findings indicate that erosion-resistant base support and good load transfer are essential design considerations for JPCP made of RCA-PCC. CRCP appears to be more suitable for the use of RCA-PCC.


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