Mechanical Properties and Uniaxial Compression Stress—Strain Relation of Recycled Coarse Aggregate Concrete after Carbonation

Chen, Tianwen; Wu, Jin; Dong, Guoqing

doi:10.3390/ma14092215

Cited by 11 publications

(6 citation statements)

References 38 publications

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“…The peak stress and slope of the ascending part of the curve declined with the increase of the replacement rate of RCA, which conformed to findings from other researchers [ 29 , 38 ]. Furthermore, as carbonation depths increased, peak stress increased and both the ascending and descending part of the stress–strain curves became steeper.…”

Section: Resultssupporting

confidence: 91%

“…In Figure 5 f, the failure mode of RAC100-35.0 mm, which was fully carbonated, is similar to the findings in the literature [ 38 ]. Although the interior of the fully carbonated concrete has a high degree of compactness, a large number of original cracks inside RCA was responsible for the failure of carbonated RAC.…”

Section: Resultssupporting

confidence: 86%

“…The results show that the peak stress of NAC, RAC50, and RAC100 specimens increased with the increase of carbonation depth. This is caused by the reactions between CO 2 and hydration products of cement, such as Ca(OH) 2 and C-S-H, which can reduce the porosity of concrete [ 33 , 34 , 37 , 38 , 39 ]. The peak stress of the concrete was increased by reducing the porosity [ 40 , 41 , 42 ].…”

Section: Resultsmentioning

confidence: 99%

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Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths

Jin

Wang

et al. 2022

Materials

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The stress–strain relation of recycled aggregate concrete (RAC) after carbonation is very important to the assessment of the durability of RAC. The objective of this study is to investigate the uniaxial compressive stress–strain curves of RAC after carbonation. In this study, the specimens were prepared with 70-mm diameter and 140-mm height cylinders, and the carbonation of the specimens was accelerated after curing 28 days. Then a uniaxial compressive loading test on the specimens was performed by using a mechanical testing machine. The results show that the peak stress (σ0) and elastic modulus (Ec) of all specimens increase with the increase of carbonation depth. The ratio of ultimate strain to peak strain (εu/ε0) and relative toughness of the specimens decrease with the increase of carbonation depth. Furthermore, carbonation has a stronger effect on natural coarse aggregate concrete (NAC) than the 50% replacement rate of RAC with similar compressive strength. Stress–strain models of recycled aggregate concrete with different carbonation depths were established according to experimental results.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths

Jin

Wang

et al. 2022

Materials

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“…The yield strength of steel is determined according to the experimental results of material properties. The elastic modulus of tension and compression is the same, where the slope of the first rising section is the elastic modulus of the steel itself, E s = 2.0 × 10 5 MPa; the second rising section is the steel strengthening section, and the slope at this time is 1/100 of the first rising section, E u = 2.0 × 10 3 MPa (Chen et al ., 2021). Poisson’s ratio ν = 0.3.…”

Section: The Establishment Of a Finite Element Modelmentioning

confidence: 99%

Study on the calculation method of the maximum number of bonded steel plates at the bottom of reinforced concrete beams

Wang,

Yu,

Xiao

et al. 2024

IJSI

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Purpose When the reinforced concrete beams are reinforced by bonding steel plates to the bottom, excessive use of steel plates will make the reinforced concrete beams become super-reinforced beams, and there are security risks in the actual use of super-reinforced beams. In order to avoid the occurrence of this situation, the purpose of this paper is to study the calculation method of the maximum number of bonded steel plates to reinforce reinforced concrete beams.Design/methodology/approach First of all, when establishing the limit failure state of the reinforced member, this paper comprehensively considers the role of the tensile steel bar and steel plate and takes the load effect before reinforcement as the negative contribution of the maximum number of bonded steel plates that can be used for reinforcement. Through the definition of the equivalent tensile strength, equivalent elastic modulus and equivalent yield strain of the tensile steel bar and steel plate, a method to determine the relative limit compression zone height of the reinforced member is obtained. Second, based on the maximum ratio of (reinforcement + steel plate), the relative limit compression zone height and the equivalent tensile strength of the tensile steel bar and steel plate of the reinforced member, the calculation method of the maximum number of bonded steel plates is derived. Then, the static load test of the test beam is carried out and the corresponding numerical model is established, and the reliability of the numerical model is verified by comparison. Finally, the accuracy of the calculation method of the maximum number of bonded steel plates is proved by the numerical model.Findings The numerical simulation results show that when the steel plate width is 800 mm and the thickness is 1–4 mm, the reinforced concrete beam has a delayed yield platform when it reaches the limit state, and the failure mode conforms to the basic stress characteristics of the balanced-reinforced beam. When the steel plate thickness is 5–8 mm, the sudden failure occurs without obvious warning when the reinforced concrete beam reaches the limit state. The failure mode conforms to the basic mechanical characteristics of the super-reinforced beam failure, and the bending moment of the beam failure depends only on the compressive strength of the concrete. The results of the calculation and analysis show that the maximum number of bonded steel plates for reinforced concrete beams in this experiment is 3,487 mm2. When the width of the steel plate is 800 mm, the maximum thickness of the steel plate can be 4.36 mm. That is, when the thickness of the steel plate, the reinforced concrete beam is still the balanced-reinforced beam. When the thickness of the steel plate, the reinforced concrete beam will become a super-reinforced beam after reinforcement. The calculation results are in good agreement with the numerical simulation results, which proves the accuracy of the calculation method.Originality/value This paper presents a method for calculating the maximum number of steel plates attached to the bottom of reinforced concrete beams. First, based on the experimental research, the failure mode of reinforced concrete beams with different number of steel plates is simulated by the numerical model, and then the result of the calculation method is compared with the result of the numerical simulation to ensure the accuracy of the calculation method of the maximum number of bonded steel plates. And the study does not require a large number of experimental samples, which has a certain economy. The research result can be used to control the number of steel plates in similar reinforcement designs.

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“…The deformation performance indicators such as peak strain ε v and elastic modulus E of the test block under different parameters (take the secant modulus at 0.4 times the peak stress in the ascending section of the axial stress-strain curve of the cylindrical test block [21]) are shown in Table 4. In order to reduce the error, three replicate test blocks were tested under each design parameter, and the average value was calculated under the premise of valid data.…”

Section: Deformation Performance Index Of Bfrac Test Blockmentioning

confidence: 99%

Experimental Study on Deformation Properties of Basalt Fiber Reinforced Recycled Aggregate Concrete

Zhu

Zhang

et al. 2022

Coatings

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In this paper, the effects of different substitution rates and basalt fiber (BF) contents on the deformation properties of recycled aggregate concrete (RAC) are studied, and the correlation degree of the changing parameters on the deformation properties of basalt fiber reinforced recycled aggregate concrete (BFRAC) is evaluated by gray correlation analysis. A total of 48 cylindrical test blocks are designed in this experiment, the failure modes of the test blocks are observed and analyzed, and performance indicators such as stress–strain curve, peak strain, and elastic modulus are obtained. The results show that the test block mainly suffers longitudinal splitting failure under uniaxial compression. The longitudinal cracks become denser and narrower with the increase in BF content. With the increase in BF content, the stress–strain curve decreases gradually, and the peak strain in the fully recycled aggregate concrete increases. There is no obvious change rule toward the peak strain with the increase in the substitution rate. The peak strain and elastic modulus of most test blocks show a trend of first decreasing and then increasing. At each substitution rate, when the BF dosage is 6 kg/m3, the elastic modulus of the test block is the minimum. Based on gray correlation analysis, the substitution rate has a greater impact on the deformation performance of BFRAC than fiber content. Therefore, an appropriate substitution rate has a better effect on improving the stiffness of test blocks and reducing the deflection of bending members.

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Mechanical Properties and Uniaxial Compression Stress—Strain Relation of Recycled Coarse Aggregate Concrete after Carbonation

Cited by 11 publications

References 38 publications

Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths

Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths

Study on the calculation method of the maximum number of bonded steel plates at the bottom of reinforced concrete beams

Experimental Study on Deformation Properties of Basalt Fiber Reinforced Recycled Aggregate Concrete

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