Internal curing effect on strength of recycled concrete and its enhancement in concrete-filled thin-wall steel tube

Wu, Kai; Chen, Feng; Xu, Chunxiao; Lin, Shiqi; Yang, Nan

doi:10.1016/j.conbuildmat.2017.07.117

Cited by 17 publications

(3 citation statements)

References 27 publications

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“…The water absorption of RBA is much larger than that of RCA and NA, as shown in Table 2; thus, in order to study the internal curing effect of RBA, an assumption is made that the curing effect of RCA and NA is ignored. In general, free water exists adequately in concrete in the first 7 days, and so the internal curing effect from RBA is mainly reflected after 7 days [30]. First, in RACI-0, which has no RBA, the strength increment ratio of the four curing periods is 1: 1.86: 2.92: 3.69 compared with the f ct from 0–7 days.…”

Section: Test Results and Analysismentioning

confidence: 99%

Internal Curing Effect and Compressive Strength Calculation of Recycled Clay Brick Aggregate Concrete

Feng

Liu

et al. 2019

Materials

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In order to investigate the internal curing effect of recycled brick aggregate (RBA) in recycled aggregate concrete (RAC) and calculate its contribution to the final compressive strength, two RAC groups with different recycled aggregates and 6 replacement ratios (r) under 4 curing ages were tested. Results show that the compressive strengths of RACI and RACII decrease steadily with the increase of r when below 40%, and that there is a significant drop once the r is higher than 60%. The internal curing effect for RAC with a low RBA ratio is mainly reflected during the curing age of 14–21 days, while for RAC with a high RBA ratio, this internal curing effect appears earlier, during 7–14 days, and becomes very obvious after 14 days. In addition, the actual tested compressive strength of RAC replaced by 100% RBA exceeds around 40% of the expected compressive strength at the age of 28 days. When the age of RAC entirely with RBA is 28 days, the compressive strength caused by the internal curing effect accounts for around 28% of the actual tested compressive strength. The most appropriate r of RBA for RAC production is between 40% to 60%. Finally, the equations for calculating the compressive strength of RAC are presented considering the curing ages, the replacement ratios and the internal curing effect of RBA. Further, a unified equation is suggested for convenience in calculation.

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Section: Test Results and Analysismentioning

confidence: 99%

Internal Curing Effect and Compressive Strength Calculation of Recycled Clay Brick Aggregate Concrete

Feng

Liu

et al. 2019

Materials

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“…Many of existing researches have been performed to study the mechanical performance of RAC confined by steel tube or fiber reinforced polymer (FRP) [ 22 , 23 ]. Wu et al [ 24 ] initiated an investigation about curing of RAC filled inside steel tubes. Taking into account internal curing, they also proposed a formula to calculate strength of recycle concrete filled steel tubes.…”

Section: Introductionmentioning

confidence: 99%

Axial compression behavior of carbon fiber reinforced polymer confined partially encased recycled concrete columns

Wang,

Liang,

Wang

et al. 2024

PLoS ONE

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Partially encased concrete (PEC) has better mechanical properties as a structure where steel and concrete work together. Due to the increasing amount of construction waste, recycled aggregate concrete (RAC) is being considered by more people. However, although RAC has more points, the performance is inferior to natural aggregate concrete (NAC). To narrow or address this gap, lightweight, high-strength and corrosion-resistant CFRP can be used, also protecting the steel flange of the PEC structure. Therefore, carbon fiber reinforced polymer (CFRP) confined partially encased recycled coarse aggregate concrete columns were studied in this paper. With respect to different slenderness ratios, recycled coarse aggregate(RCA) replacement ratios, and number of CFRP layers, the performance of the proposed CFRP restrained columns are reported. The RCA replacement ratio is analyzed to be limited negative impact on the bearing capacity, generally within 6%. As for the slenderness ratio, the bearing capacity increased with it. However, wrapping CFRP significantly increased the bearing capacity. Considering the arch factor, a simple formula for calculating the ultimate strength of CFRP-confined partially encased RAC columns is developed based on EC4 and GB50017-2017. By comparison with the experimental values, the error is within 10%.

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“…However, for the relatively poorer mechanical properties of RAC, they are generally limited to applications that do not require high structural performance. To fix such drawback, recycled aggregate concrete-filled steel tube columns were then developed, behavior of which were then studied by several researchers [8,9]. For example, Wang et al [10] investigated the effect of the strength of the parent waste concrete on the creep behavior of recycled aggregate concrete-filled steel tubes (RACFST), and a creep model for RACFST was provided.…”

Section: Introductionmentioning

confidence: 99%

Bond Behavior of CRACFST Columns after Exposure to Elevated Temperatures

Liang

2019

Advances in Civil Engineering

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The bond behavior of post-heated circular recycled aggregate concrete-filled steel tube (CRACFST) columns is experimentally investigated in this paper. A total of 24 heated push-out CRACFST specimens are prepared; at the same time, 3 unheated specimens are also prepared and tested for comparison. This paper investigates the effects of five variable parameters, namely, temperature, exposure period, recycled coarse aggregate (RCA) replacement ratio, concrete strength, and interface length-to-diameter ratio, on the bond stress-slip curves and bond strength. The results show that the push-out CRACFST specimens exhibit some differences in bond stress-slip curves at both ambient and high temperature. The bond strength increases with increasing temperature. Other parameters also have influence to some extent. On the basis of a regression analysis of the experimental data, a revised bond strength model is proposed to predict the post-heated bond behavior between recycled aggregate concrete and circular steel tube.

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Internal curing effect on strength of recycled concrete and its enhancement in concrete-filled thin-wall steel tube

Cited by 17 publications

References 27 publications

Internal Curing Effect and Compressive Strength Calculation of Recycled Clay Brick Aggregate Concrete

Internal Curing Effect and Compressive Strength Calculation of Recycled Clay Brick Aggregate Concrete

Axial compression behavior of carbon fiber reinforced polymer confined partially encased recycled concrete columns

Bond Behavior of CRACFST Columns after Exposure to Elevated Temperatures

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