Effect of Variability of Recycled Aggregate on Properties of Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 1122-1132
Author(s):  
Chao Jun Wan ◽  
Xu Chen ◽  
Teng Li ◽  
Tai Zhong Huang ◽  
Tian Ming Deng
Keyword(s):  
Mechanical Properties ◽  
High Variability ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Hardened Cement ◽  
Essential Factor ◽  
Hardened Cement Paste ◽  
Aggregate Concrete ◽  
Natural Aggregate

Low, medium and high variability of aggregates of concrete were designed and prepared and the influence of variability of recycled aggregates on the mechanical properties and durability of concretes was investigated. The experimental results indicated that the kinds of strengths, static compressive elastic modulus and durability of recycled concrete were decreased at engineering-acceptable level compared with natural aggregate concrete; the most properties of recycled concrete with high variability of recycled aggregates are not very different from that of recycled concrete with medium variability of recycled aggregates even that of natural aggregate concretes; however, the variability of properties of recycled concrete with high variability of recycled aggregates are much different from that of medium variability of recycled aggregates and more different from that of natural aggregate concretes, which means if only one or limited properties of recycled concrete were tested, the existing high variability of properties of concrete may not be revealed to a full enough extent, and the possible neglect of this high variability may result in potential engineering risk in application of high variability of recycled aggregate; the content of hardened cement paste and mortar attached to the recycled aggregate is found to be the essential factor to influence the properties of recycled concrete.

scholarly journals Virtual Revision on Compressive Srength of Conventional Concrete and Recycled Aggregate Concrete Consisting Treated Recycled Aggregate

2019 ◽  
Vol 8 (3) ◽  
pp. 3439-3443
Keyword(s):  
Experimental Studies ◽  
Strength Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Natural Aggregate

Use of reused aggregate in concrete can be useful for the ecological protection and economical terms. The application of recycled has been started in many construction projects. Paper hear says the basic properties of recycled concrete aggregate. It similarly relates the properties with natural aggregate, similarly the properties of recycled aggregates concrete were also determined and explained here. For the concrete grades of M25 and M30, the recycled aggregate concrete is produced by changing the natural aggregate, by recycled aggregate in conventional concrete with 5%, 10% and 15% of weight of natural aggregates. Experimental studies were carried out on influence of recycled aggregate treatment and comparison of strength properties of conventional cement concrete and recycled aggregate concrete at the curing of 7days and 28 days. They are two types of treatments under the considerations for recycled aggregates are Abrasion of recycled aggregate and chemical immersion

Study of Surface Modification of Recycled Aggregate and Mechanical Properties of the Resulting Concrete

2013 ◽  
Vol 712-715 ◽  
pp. 961-965
Author(s):  
Shu Qing Yang ◽  
Ting Peng ◽  
Wai Ching Tang ◽  
Hong Zhi Cui
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Performance Test ◽  
Test Methods ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Test Method ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete

In this paper, a method of aggregate surface modification using cement paste with RLP (Redispersable Latex Powder) was proposed aiming to improve properties of recycled aggregates and the resulting concrete. In this study, the cement pastes with different dosages of RLP on RA surface modification were used and the effects on the mechanical properties of the resulting concretes were studied. The experiments were carried in accordance with specifications and test methods in Building pebble and gravel (GB/T 14685-2001) and Ordinary concrete mechanics performance test method standard (GB/T 50081-2002). The test results showed that the properties of recycled aggregates were not as good as those of natural aggregates, thus resulting in poorer mechanical properties of the recycled aggregate concrete. By means of aggregate surface modification, the values of water absorption of the recycled aggregate were reduced and consequently the mechanical properties (i.e. compressive strength and elastic modulus) of the resulting recycled concrete were increased. This research provides some useful practical insights to improving mechanical properties of recycled aggregate concrete.

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

Study on the Basic Mechanical Properties of Recycled Concrete Hollow Block Masonry

2013 ◽  
Vol 438-439 ◽  
pp. 749-755 ◽  
Author(s):  
Tong Hao ◽  
Dong Li
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Shear Behavior ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Test Results ◽  
Aggregate Concrete ◽  
Mortar Strength ◽  
Hollow Block

By the experimental studying on the basic mechanical properties of recycled concrete hollow block masonry, the compressive and shear behavior of recycled aggregate concrete hollow block masonry under different mortar strength were analyzed. Research indicated that the compressive and shear behavior of recycled aggregate concrete hollow block masonry was similar to that of ordinary concrete hollow block masonry. The normal formula was recommended to calculate the compressive strength of the masonry. The shear strength of the masonry was affected by the mortar strength. The shear strength calculation formula of recycled concrete hollow block masonry was proposed according to the formula of masonry design code. The calculating results were in good agreement with the test results.

Study on Performance of Recycled Aggregate Concrete

2011 ◽  
Vol 477 ◽  
pp. 280-289 ◽  
Author(s):  
Shao Wei Yao ◽  
Zhen Guo Gao ◽  
Chang Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Physical And Mechanical Properties ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chemical Solution ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Natural Aggregate ◽  
Strength And Durability

The properties of recycled coarse aggregate and the slump, the physical and mechanical properties and durability of recycled aggregate concrete were studied through tests. The results indicate that the slump, compressive strength and durability of concrete with recycled aggregate are lower than that of concrete with natural aggregate when recycled coarse aggregate fully absorbs water. However, the slump can be similar to that of concrete with natural aggregate. The properties of recycled aggregate concrete can be improved by strengthening the recycled coarse aggregate, and it is also found that the recycled coarse aggregate strengthened by grinding is superior to that soaked by chemical solution.

scholarly journals MECHANICAL PROPERTIES OF RECYCLED AGGREGATE CONCRETE WITH STEEL FIBER: A REVIEW

2019 ◽  
Vol 26 (3) ◽  
pp. 37-42
Author(s):  
Ashtar S. Al-Luhybi
Keyword(s):  
Mechanical Properties ◽  
Steel Fiber ◽  
Recycled Aggregate Concrete ◽  
Strength Characteristics ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete ◽  
Building Process

In the building process, the recycling of aggregates arising from building and demolition debris is one of the best alternatives to maintain the environment and the areas needed to bury these debris. It also helps to preserve natural concrete sources from depletion efficiently. The use of recycled aggregates in new concrete manufacturing, however, leads to a decrease in concrete\\\’s strength characteristics. This reduction rises with the rise in the percentage of recycled aggregates used in concrete, which has caused many researchers to undertake many researches on how to enhance the characteristics of recycled aggregate-containing concrete. This paper presents several studies that examined the effect of adding steel fiber to improve the properties of concrete containing a coarse recycled aggregate.

scholarly journals Studies on Hemp and Recycled Aggregate Concrete

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Samer Ghosn ◽  
Nour Cherkawi ◽  
Bilal Hamad
Keyword(s):  
Mechanical Properties ◽  
Fiber Length ◽  
Plain Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Silane Treatment ◽  
Hemp Fiber ◽  
Fiber Treatment

Abstract This paper reports on the first phase of a multi-phase research program conducted at the American University of Beirut (AUB) on “Hemp and Recycled Aggregates Concrete” (HRAC). HRAC is a new sustainable concrete material where hemp fibers are incorporated in the mix, the coarse aggregate content is reduced by 20% of the concrete volume, and 50% of the natural coarse aggregates (NCA) are replaced by recycled concrete aggregates (RCA), thus saving on natural resources and addressing the problem of waste material disposal. The effect of the new material on concrete consistency and hardened mechanical properties was studied. Also, few durability tests were conducted. Variables included percentage replacement of NCA by RCA (0 or 50%), maximum size aggregate (10 or 20 mm), hemp fiber length (20 or 30 mm), and hemp fiber treatment (alkali or silane or acetyl). Fiber characterization tests were conducted including morphology, crystallinity, and thermal analysis. The tests indicated that alkali and acetyl fiber treatments were better than the silane treatment in removing impurities on the fiber surface. Also, alkali and acetyl treatments have increased the crystallinity of the fibers while silane treatment decreased it. Results of mechanical properties tests showed that while HRAC has considerable lower compressive strength and modulus of elasticity than plain concrete, the flexural strength and splitting tensile strength are not significantly affected. The flexural stress–strain behavior of HRAC is ductile as compared to the brittle behavior of the plain concrete beams indicating positive impact on toughness and energy dissipation. The durability tests indicated that whereas HRAC mixes have higher absorption than plain concrete, they have better thermal properties and their resistance to freeze–thaw cycles is comparable to plain concrete. All test results were not significantly affected by fiber length or fiber treatment.

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.

Shear strength of reinforced concrete beams with recycled aggregates

2019 ◽  
Vol 22 (8) ◽  
pp. 1938-1951 ◽  
Author(s):  
George Wardeh ◽  
Elhem Ghorbel
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Strain Softening ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Opening Displacement ◽  
Aggregate Concrete ◽  
Natural Aggregate ◽  
Hinge Model

This article presents an experimental program on the shear behavior of beams without transversal reinforcement manufactured with natural aggregate concrete and 100% recycled aggregate concrete. The beams were tested under four-point bending for a shear span-to-depth ratio ( a/ d) equal to 1.5 and 3.0. The mechanical properties of two mixes were characterized in terms of compressive strength, splitting tensile strength, and elastic modulus. Three-point bending tests were performed on plain pre-notched samples in order to determine the fracture properties by an inverse analysis of experimental force–crack mouth opening displacement curves using the analytical nonlinear hinge model and a power law strain-softening relationship. The strain-softening law is described by two parameters being, respectively, the power n and the critical crack opening displacement wc. The experimental results show that, for the same class of compressive strength, tensile strength, fracture energy, and the shear strength of recycled aggregate concrete are lower than natural aggregate concrete. The decrease in the fracture energy and the shear strength is consistent with the decrease in the splitting tensile strength of the recycled aggregate concrete mixes compared to the natural aggregate concrete. Critical shear crack theory was adopted to model the shear behavior of beams tested with a/ d = 3.0. For an accurate evaluation of the deformation capacity of tested beams, the nonlinear hinge model for recycled concrete members was extended to recycled concrete sections. For deep beams ( a/ d = 1.5), the strut-and-tie model was used. Finally, comparisons of prediction models to a wide range of experimental data are presented.

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