scholarly journals Optimizing the Mixing Proportion with Neural Networks Based on Genetic Algorithms for Recycled Aggregate Concrete

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Sangyong Kim ◽  
Hee-Bok Choi ◽  
Yoonseok Shin ◽  
Gwang-Hee Kim ◽  
Deok-Seok Seo
Keyword(s):  
Neural Networks ◽  
Sensitivity Analysis ◽  
Genetic Algorithms ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mixing Ratio ◽  
Construction Process ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Mixing Proportion

This research aims to optimize the mixing proportion of recycled aggregate concrete (RAC) using neural networks (NNs) based on genetic algorithms (GAs) for increasing the use of recycled aggregate (RA). NN and GA were used to predict the compressive strength of the concrete at 28 days. And sensitivity analysis of the NN based on GA was used to find the mixing ratio of RAC. The mixing criteria for RAC were determined and the replacement ratio of RAs was identified. This research reveal that the proposed method, which is NN based on GA, is proper for optimizing appropriate mixing proportion of RAC. Also, this method would help the construction engineers to utilize the recycled aggregate and reduce the concrete waste in construction process.

scholarly journals Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2312
Author(s):  
Xin Liang ◽  
Fang Yan ◽  
Yuliang Chen ◽  
Huiqin Wu ◽  
Peihuan Ye ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Force ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Displacement Curve ◽  
Direct Shear ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Failure ◽  
Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

Experimental Study on Compressive Strength of Recycled Aggregate Concrete with Different Replacement Ratios

2012 ◽  
Vol 174-177 ◽  
pp. 1277-1280 ◽  
Author(s):  
Hai Yong Cai ◽  
Min Zhang ◽  
Ling Bo Dang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Failure Mode ◽  
Failure Process ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Replacement Ratio ◽  
Aggregate Concrete

Compressive strengths of recycled aggregate concrete(RAC) with different recycled aggregates(RA) replacement ratios at 7d, 28d, 60d ages are investigated respectively. Failure process and failure mode of RAC are analyzed, influences on compressive strength with same mix ratio and different RA replacement ratios are analyzed, and the reason is investigated in this paper. The experimental results indicate that compressive strength of recycled concrete at 28d age can reach the standard generally, it is feasible to mix concrete with recycled aggregates, compressive strength with 50% replacement ratio is relatively high.

scholarly journals Compressive performance of 50 MPa strength concrete-filled square and circular tube (CFT) columns using recycled aggregate

2018 ◽  
Author(s):  
Sung-Mo Choi ◽  
Won Ho Choi ◽  
Kangseok Lee ◽  
Jae-Yong Ryoo ◽  
Sunhee Kim ◽  
...  
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Steel Pipe ◽  
Strength Development ◽  
Fine Aggregate ◽  
Mixing Ratio ◽  
Compressive Behavior ◽  
Aggregate Concrete ◽  
Cft Column

Recycled aggregate is an environmentally self-sustainable solution that can reduce construction waste and replace natural aggregates. However, there is a disadvantage in concrete such as initial strength drop and long-term strength development. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. In order to develop a concrete with compressive strength of 50 MPa as a recycled aggregate, we carried out a mixing experiment and fabricated 18 specimens to confirm the compressive behavior of a RCFT (Recycled Concrete Filled Tube) column that can be applied to actual buildings. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. The optimum mixing ratio for recycled aggregate concrete to be filled in the CFT filled steel pipe was found through three concrete preliminary mixing experiments. In addition, the compression test of the RCFT column was carried out to observe and analyze the buckling shape of the CFT column. Based on the analysis of the buckling configuration and the experimental data, the load-displacement curves of the specimens were drawn and the compressive behavior was analyzed. 

scholarly journals Basic Mechanical Properties of Basalt Fiber Reinforced Recycled Aggregate Concrete

2017 ◽  
Vol 11 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Huaxin Liu ◽  
Jianwei Yang ◽  
Xiangqing Kong ◽  
Xuxu Xue
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Basalt Fiber ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mixing Ratio ◽  
Fiber Reinforced ◽  
Aggregate Concrete ◽  
Chopped Basalt Fiber

In order to study the basic mechanical properties of basalt fiber reinforced recycled aggregate concrete, the concrete mix ratio, the length and the volume mixing ratio of chopped basalt fiber yarn are designed for changing factors. A total of 324 specimens have been completed for this investigation. The compressive strength, splitting tensile strength, elastic modulus and axial compressive strength of basalt fiber recycled concrete have carried on the experimental study and theoretical analysis as 81 specimens, respectively. In all specimens, coarse aggregate were replaced by recycled aggregate with a replacement rate of 100%. Experimental results show that the failure process and failure pattern of basalt fiber recycled concrete and ordinary concrete are similar; With the improvement of concrete strength grade; When the volume mixing ratio of chopped basalt fiber yarn is 0.2%, the mechanic performance can effectively improve, and the length of chopped basalt fiber has less effect on the mechanical indexes; The conversion relation between common concrete mechanics index is no longer suitable for basalt fiber recycled concrete, new conversion formulas for basalt fiber recycled concrete between the mechanics index were presented through fitting experimental data.

scholarly journals Reliability-Based Analysis of Recycled Aggregate Concrete under Carbonation

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Flora Faleschini ◽  
Mariano Angelo Zanini ◽  
Lorenzo Hofer
Keyword(s):  
Prediction Models ◽  
Probabilistic Method ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Ratio ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Carbonation Resistance ◽  
Environmental Actions ◽  
Experimental Works

Durability represents a crucial issue for evaluating safety and serviceability of reinforced concrete structures. Many studies have already focused on carbonation-induced corrosion of natural aggregate concrete (NAC) structures, leading to several prediction models to estimate carbonation depth. Less research is devoted instead on recycled aggregate concrete (RAC), about which limited experimental works exist aimed at assessing the carbonation coefficient in accelerated tests. Additionally, deteriorating processes are subject to uncertainty, when defining materials, geometry, and environmental actions during the service life of structures. This work presents a reliability-based analysis of carbonation resistance of RACs, using experimental carbonation coefficients derived from the literature, and applied in the full-probabilistic method prosed in fib Bulletin 34. Results demonstrate how aggregates replacement ratio and w/c ratio influence the reliability of RAC carbonation resistance.

Axial behavior of carbon fiber-reinforced polymer–confined recycled aggregate concrete-filled steel tube slender square columns

2021 ◽  
pp. 136943322110339
Author(s):  
Jiongfeng Liang ◽  
Siqi Lin ◽  
Mizan Ahmed
Keyword(s):  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Fiber Reinforced Polymer ◽  
Recycled Aggregate ◽  
Fiber Reinforced ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Filled Steel Tube ◽  
Reinforced Polymer ◽  
Axial Behavior

The behavior of fiber-reinforced polymer (FRP)–confined recycled aggregate concrete-filled steel tube (RACFT) columns is barely studied. Especially, that of slender specimens has not been investigated so far. In this article, an experimental test of FRP-confined RACFT slender square columns was conducted to study the influences of recycled aggregate (RA) replacement ratios, FRP thicknesses, and wrapping schemes on their axial behavior. Results in this article suggest that the RA replacement ratio barely affects the initial stiffness of load-deflection curves of specimens. Moreover, the specimen with a higher RA replacement ratio has a lower axial stress but larger strain at the peak point. The external FRP jackets (either partial or full wrap) can effectively improve the performance of axially loaded RACFT columns, and the improvement of ductility due to the increase of the FRP thickness is more significant than that of axial compressive strength. Additionally, it was found that the axial strength and ultimate axial strain decrease with increasing slenderness ratios. Furthermore, the influences of slenderness ratios on the behavior of such columns are more significant for the column with a larger length-to-width ratio. Finally, a design model for FRP-confined RACFT slender square columns is developed, which can predict the results of the present test accurately.

Compressive Behaviour of Recycle Concrete Cubes after Freeze-Thaw Cycles

2013 ◽  
Vol 671-674 ◽  
pp. 1865-1868
Author(s):  
Tao Long ◽  
Shi Hai Dong ◽  
Shi Ming Cui ◽  
Qing Yuan Wang
Keyword(s):  
Carrying Capacity ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Recycle Concrete ◽  
Ultimate Carrying Capacity

It is widely considered that crushed construction aggregate waste creates a lower compressive strength kind of concrete. This paper presents experimental investigation on axial compression strength of 18 recycled aggregate concrete cubes under the freeze-thaw test. The research has focused on the effect of the freezing-thawing test on the ultimate carrying capacity of recycled concrete cubes with different coarse aggregate replacement ratio. This study confirms that freezing-thawing cycles have a greater effect on the ultimate bearing capacity of recycled concrete cubes. Some measures should be taken to prevent the recycle concrete from the freeze-thaw damage, for example add air entraining agent to concrete.

Mechanical properties of recycled aggregate concrete under multiaxial compression

2020 ◽  
Vol 23 (12) ◽  
pp. 2529-2538
Author(s):  
Yumei Wang ◽  
Zhiheng Deng ◽  
Jianzhuang Xiao ◽  
Jun Sheng
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Failure Criterion ◽  
Stress Ratio ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Multiaxial Compression

The mechanical properties of recycled aggregate concrete under multiaxial compression were tested by servo-controlled setup (TAWZ-5000/3000). Properties of strength and stress–strain relation were obtained, and the influence factors of stress ratio and recycled coarse aggregate replacement ratio were analyzed. The results show that the strength of recycled aggregate concrete under multiaxial compression is higher than that of under uniaxial state, the stress ratio and recycled coarse aggregate replacement ratio have obvious effect on strength, and the shape of stress–strain curve is also varied with different levels of the two factors. Failure criterion can reflect the strength relation for recycled concrete under multiaxial stress state. Kupfer’s failure criterion is selected to describe strength properties under biaxial stress state, and the failure envelope reflects the energy absorption of different mix series. Based on octahedral stress theory, the tensile and compressive meridians have been proposed to analyze the strength characteristics under triaxial compression, and the theoretical values are well coherent with the test data.

Experiment on Properties of Recycled Aggregate Concrete

2013 ◽  
Vol 377 ◽  
pp. 99-103 ◽  
Author(s):  
Hai Tao Yang ◽  
Shi Zhu Tian
Keyword(s):  
Mechanical Properties ◽  
Abrasion Resistance ◽  
Coarse Aggregate ◽  
Objective Measure ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Aggregate Content

Objective: Measure and study the mechanical properties and abrasion resistance of recycled aggregate concrete in order to provide experimental basis for the application of recycled aggregate concrete in engineering. Method: Use recycled aggregate concrete with replacement ratio of recycled coarse aggregate respectively for 0%, 30%, 50%, 80% and 100% to do the slump, compressive strength, modulus of elasticity and abrasion resistance tests on them. Result: The workability of concrete decreases with the increase of recycled coarse aggregate content. Mechanical properties of concrete change as the replacement ratios of recycled coarse aggregate change. Conclusion: The recycled aggregate concrete and natural aggregate concrete have similar abrasion resistance. The recycled aggregate concrete can be applied in engineering.

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