Analysis of Stress - Strain Curve on Recycled Aggregate Concrete under Uniaxial and Conventional Triaxial Compression

2010 ◽  
Vol 168-170 ◽  
pp. 900-905 ◽  
Author(s):  
Hai Feng Yang ◽  
Zhi Heng Deng ◽  
Ying Huang
Keyword(s):  
Lateral Pressure ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Confining Pressures

43 Φ50mm × 100mm column stress - strain curve tests are completed through RMT-201, which studied the compressive stress - strain curves of recycled aggregate concretes at distinct confining pressures under conventional triaxial stress state. This article, has analyzed the influence of different water-cement ratios, confining pressures on the curves, and raised constitutive equations of triaxial compression stress - strain curves for the different strength of recycled aggregate concretes.The brittleness indexes for recycled aggregate concrete under distinct confining pressures were analyzed contrastively. The result showed that: the failure modes of recycled aggregate concrete specimens are similar to those of ordinary concretes, but the final failure patterns of recycled aggregate and ordinary aggregate are quite different; with the increase of lateral pressure, the peak stress and peak strain of recycled aggregate concrete show linear growth; recycled aggregate concrete compressive stress - strain curves under the uniaxial and triaxial stress states are similar to ordinary aggregate concrete, yet peak strain shows signs of larger growth; with the increase of lateral pressure, the brittleness of recycled aggregate concrete reduces. The brittleness index of high-strength recycled aggregate concrete is larger wholly than that of ordinary recycled aggregate concrete and with confining pressure reaching a certain value, the brittleness index remains stable.

Experimental Research on Mechanical Properties of Recycled Aggregate Concrete under Uniaxial Loading

2013 ◽  
Vol 671-674 ◽  
pp. 1736-1740
Author(s):  
Xue Yong Zhao ◽  
Mei Ling Duan
Keyword(s):  
Elastic Modulus ◽  
Coarse Aggregate ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Peak Strain ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate

The complete stress-strain curves of recycled aggregate concrete with different recycled coarse aggregate replacement percentages were tested and investigated. An analysis was made of the influence of varying recycled coarse aggregate contents on the complete stress-strain curve, peak stress, peak strain and elastic modulus etc. The elastic modulus of RC is lower than natural concrete (NC), and with the recycled coarse aggregate contents increase, it reduces. While with the increase of water-cement ratio (W/C), recycled concrete compressive strength and elastic modulus improve significantly. In addition, put forward a new equation on the relationship between Ec and fcu of the RC.

scholarly journals Stress–Strain Curve and Carbonation Resistance of Recycled Aggregate Concrete after Using Different RCA Treatment Techniques

2021 ◽  
Vol 11 (9) ◽  
pp. 4283
Author(s):  
Long Li ◽  
Dongxing Xuan ◽  
Chisun Poon
Keyword(s):  
Elastic Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Treatment Techniques ◽  
Carbonation Resistance

Five recycled coarse aggregate (RCA) treatment techniques including flow-through carbonation, pressurized carbonation, wet carbonation, nano silica (NS) pre-spraying and combined pressurized carbonation with NS pre-spraying, were utilized to improve the performance of recycled aggregate concrete (RAC). The characteristics of the stress–strain curves of RACs including peak stress, peak strain, elastic modulus, ultimate strain and toughness were evaluated after using the above RCA treatment techniques. A theoretical model for natural aggregate concrete was used to analyse the stress–strain curve of RAC. Additionally, the carbonation resistance of RAC after using different RCA treatment techniques were investigated. The results showed that the calculated stress–strain curve of RAC based on the theoretical model matched well with the experimental results. Among the three types of carbonation techniques, pressurized carbonation caused the highest improvement in peak stress and elastic modulus of RAC, followed by flow-through carbonation, the last was wet carbonation. The NS pre-spraying method contributed to even higher improvement in peak stress and elastic modulus of RAC than the pressurized carbonation method. The combined pressurized carbonation with NS pre-spraying exhibited the highest enhancement of RAC because both the RCA and the new interface transition zone (ITZ) were improved. The carbonation resistance of RAC was improved after using all the studied RCA treatment techniques.

Mathematical Model for Compressive Stress-Strain Curve of Recycled Aggregate Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 521-524 ◽  
Author(s):  
Wei Wang ◽  
Li Jun Yang ◽  
Xiao Ni Wang
Keyword(s):  
Mathematical Model ◽  
Compressive Stress ◽  
Strain Curve ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Experimental Investigations ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
New Model

For the effective utilization of recycled aggregate concrete (RAC), it is necessary to correctly describe its compressive stress-strain curve (SSC) in theoretical and numerical analysis as well as engineering design of RAC structures. The objective of this study is to establish a good mathematical model for SSC of RAC. Based on energy dissipation theory, the differential governing equation of SSC is deduced and a new mathematical model is obtained. The new model can well describe both hardening type SSC and softening type SSC. It can overcome the shortcoming of the traditional model. Finally, good agreements have been found between the new model and the experimental investigations.

scholarly journals Axial Stress-Strain Performance of Recycled Aggregate Concrete Reinforced with Macro-Polypropylene Fibres

2021 ◽  
Vol 13 (10) ◽  
pp. 5741
Author(s):  
Muhammad Junaid Munir ◽  
Syed Minhaj Saleem Kazmi ◽  
Yu-Fei Wu ◽  
Xiaoshan Lin ◽  
Muhammad Riaz Ahmad
Keyword(s):  
Axial Stress ◽  
Peak Stress ◽  
Polypropylene Fibre ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Peak Strain ◽  
Stress Strain ◽  
Polypropylene Fibres ◽  
Aggregate Concrete

The addition of macro-polypropylene fibres improves the stress-strain performance of natural aggregate concrete (NAC). However, limited studies focus on the stress-strain performance of macro-polypropylene fibre-reinforced recycled aggregate concrete (RAC). Considering the variability of coarse recycled aggregates (CRA), more studies are needed to investigate the stress-strain performance of macro-polypropylene fibre-reinforced RAC. In this study, a new type of 48 mm long BarChip macro-polypropylene fibre with a continuously embossed surface texture is used to produce BarChip fibre-reinforced NAC (BFNAC) and RAC (BFRAC). The stress-strain performance of BFNAC and BFRAC is studied for varying dosages of BarChip fibres. Results show that the increase in energy dissipation capacity (i.e., area under the curve), peak stress, and peak strain of samples is observed with an increase in fibre dosage, indicating the positive effect of fibre addition on the stress-strain performance of concrete. The strength enhancement due to the addition of fibres is higher for BFRAC samples than BFNAC samples. The reduction in peak stress, ultimate strain, toughness and specific toughness of concrete samples due to the utilisation of CRA also reduces with the addition of fibres. Hence, the negative effect of CRA on the properties of concrete samples can be minimised by adding BarChip macro-polypropylene fibres. The applicability of the stress-strain model previously developed for macro-synthetic and steel fibre-reinforced NAC and RAC to BFNAC and BFRAC is also examined.

scholarly journals Experimental and Theoretical Investigation on the Thermo-Mechanical Properties of Recycled Aggregate Concrete Containing Recycled Rubber

2021 ◽  
Vol 8 ◽  
Author(s):  
Yunchao Tang ◽  
Wanhui Feng ◽  
Zheng Chen ◽  
Yumei Nong ◽  
Minhui Yao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Microstructural Analysis ◽  
Strain Curve ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Recycled Rubber

The utilization of recycled aggregates made from construction wastes and recycled rubber made from waste tires is an effective method to realize the sustainable development. Thus, this study aims to determine the feasibility of using recycled aggregate concrete containing rubber, named rubberized recycled aggregate concrete (RRAC) as a new type of green-building material. The experimental carbon emissions test verified RRAC as a low-carbon material. In addition, the residual mechanical properties of RRAC were investigated under elevated temperatures. After exposure at 200, 400, and 600 C for 60 min, the stress−strain curve, compressive strength, energy absorption capacity, and spalling resistance of RRAC with recycled aggregate replacement ratios of 50 and 100%, rubber contents of 0, 5, 10, and 15% were explored with microstructural analysis. Moreover, empirical models were proposed to describe the effects of heated temperatures and rubber contents on the stress–strain relationship of RRAC. The results indicated that the rubber particles could reduce the spalling of specimens based on the vapor pressure theory. Therefore, this study provided scientific guidance for the design of structures made with RRAC for resisting high temperatures.

scholarly journals Compressive Mechanical Properties of a Novel Recycled Aggregate Concrete with Recycled Lightweight Aggregate

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Anjun Li ◽  
Gaoqiang Zhou ◽  
Xianggang Zhang ◽  
Ercong Meng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Lightweight Aggregate ◽  
Ultimate Strain ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Peak Strain ◽  
Replacement Ratio ◽  
Stress Strain ◽  
Aggregate Concrete

A novel recycled aggregate concrete was prepared by replacing the natural aggregate with recycled lightweight aggregate. Subsequently, the mechanical properties and compressive stress-strain constitutive relation of the recycled lightweight aggregate concrete (RLWAC) were explored. For this purpose, the recycled lightweight aggregate (RLWA) replacement ratio (0%, 25%, 50%, 75%, and 100%) was selected as a variable, and the compressive strength of 15 cube and 30 prism specimens was evaluated. The failure morphology of the specimen was subsequently characterized, along with the cubic compressive strength, axial compressive strength, peak strain, ultimate strain, and other performance indices. The influence of the replacement ratio for the specimen indices of the RLWAC was also analyzed. It was observed that the dry apparent density of RLWAC decreased gradually on increasing the replacement ratio. Compared with 0% replacement ratio, a decrease of 6.50%, 11.39%, 21.84%, and 27.54% was observed, respectively. On enhancing the RLWA replacement ratio, the compressive strength, peak strain, and ultimate strain of RLWAC were observed to be gradually reduced. As the replacement ratio was increased from 75% to 100%, the peak strain was noted to decrease the most by about 6.8%. As the replacement ratio was increased from 50% to 75%, the ultimate strain decreased the most by about 14.2%. Based on the experimental findings, the functional relationships of the strength indices and the conversion value of each strength index with the replacement ratio were also established. Finally, based on the model proposed by the existing model, the stress-strain equation of RLWAC was developed, and the fitting results were observed to be in good agreement with the test results.

scholarly journals Compressive Behavior, Microstructural Properties, and Freeze–Thaw Behavior of Tailing Recycled Aggregate Concrete with Waste Polypropylene Fiber Addition

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6712
Author(s):  
Fan Xu ◽  
Tao Li ◽  
Chenghua Li ◽  
Zhijun Li ◽  
Sheliang Wang ◽  
...  
Keyword(s):  
Polypropylene Fiber ◽  
Strain Curve ◽  
Peak Stress ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Cement Matrix ◽  
Peak Strain ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Thaw Cycle

To improve the high brittleness of recycled aggregate concrete containing iron ore tailings (TRAC), the feasibility of adding polypropylene fiber (PPF) to TRAC was studied by performing a compression stress–strain curve test, scanning electron microscope characterization, and a freeze–thaw cycle test. The results indicated that PPF had a beneficial impact on reducing the brittleness of TRAC. With the increase in PPF content, the peak strain increased, the elastic modulus decreased, and the peak stress and energy absorption capacity increased at first and then decreased. Furthermore, the microstructure investigation revealed that the interface friction between the PPF, aggregate, and cement matrix was the main source of energy dissipation. When the load acted on the concrete, the stress was dispersed to the fiber monofilaments, thus effectively enhancing the peak stress and peak strain of concrete and suppressing the generation and development of cracks in the concrete. In terms of freeze–thaw resistance, adding a small amount of PPF could reduce the negative effects of the freeze–thaw process on the cement matrix. On the premise of ensuring strength, the waste utilization should be as high as possible. Therefore, it was suggested that the content of PPF in fiber-reinforced tailings recycled aggregate concrete (TRAC-PP) should be 0.6%.

Mechanical Behaviors of High Performance Recycled Aggregate Concrete

2011 ◽  
Vol 80-81 ◽  
pp. 190-194
Author(s):  
Shu Hua Liu ◽  
Zhi Yang Gao ◽  
Li Hua Li
Keyword(s):  
Compressive Stress ◽  
High Performance ◽  
Constitutive Relations ◽  
Strain Curve ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mechanical Behaviors ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Uniaxial Compressive Stress

In this testing research, a series of High Performance Recycled Aggregate Concrete (HPRAC) with recycled aggregate were prepared and their mechanical behaviors were tested, especially uniaxial compressive stress-strain behavior. The influence of the recycled aggregate replacement on mechanical behaviors of HPRAC was studied by changing replacement ratio of recycled aggregate. Testing results show that the strength of HPRAC decrease a little with the increase of the content of recycled aggregate; the uniaxial compressive stress-strain curve of HPRAC is similar to that of ordinary concrete, and the ductibility of HPRAC improve with the increase of the content of recycled aggregate; the fitted regression curves (especially numerical model) approach to measured curves and can be used in constitutive relations analysis for concrete structure.

scholarly journals Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1257
Author(s):  
Shuling Gao ◽  
Guanhua Hu
Keyword(s):  
Strain Rate ◽  
Lateral Pressure ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Pressure Level ◽  
Strain Rates ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

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