scholarly journals Mechanical Properties of a New Type Recycled Aggregate Concrete Interlocking Hollow Block Masonry

2021 ◽  
Vol 13 (2) ◽  
pp. 745
Author(s):  
Jie Li ◽  
Hao Zhou ◽  
Wenwen Chen ◽  
Zhongfan Chen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Shear Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Test Results ◽  
Hollow Block ◽  
New Type ◽  
Building Engineering

Considering the advantages of energy conservation and reducing the construction skill requirement of the workers, a new type of interlocking hollow block using recycled aggregates concrete (IHB-RAC) with the compressive strength up to 10 Mpa was proposed, which could help improve more than 56% of the construction efficiency compared to commonly used concrete hollow blocks. In order to study the mechanical properties and promote the application of this new type block in building engineering, the masonries considering different strengths of mortar and the concrete used in the grouting holes were designed, and the corresponding compressive and shear strength, as well as the failure mode of the masonries were studied according to the test results. Then, experimental results were compared with the calculated values obtained from Chinese code GB50003-2011 to check the suitability of the standards. In order to make an accurate prediction of the compressive strength of the masonry, modifying coefficients were suggested considering the positive contributions of the connecting keys. In addition, according to the test results, an appropriate calculation method for accurately predicting the shear strength of the grouted IHB-RAC masonry was proposed by separately considering the effort of the mortar and the grouting hole concrete.

Shear properties of a new type recycled aggregate concrete interlocking hollow block masonry with axial load

2021 ◽  
pp. 136943322110125
Author(s):  
Jie Li ◽  
Hao Zhou ◽  
Wenwen Chen ◽  
Zhongfan Chen
Keyword(s):  
Shear Strength ◽  
Axial Stress ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Positive Contribution ◽  
Shear Properties ◽  
Hollow Block ◽  
New Type ◽  
Building Engineering

Comprehensively considering the positive contribution of energy conservation and the reduction of the construction skill requirement for workers, a new type of interlocking hollow block using recycled aggregates concrete (IHAC) with the compressive strength defined as MU10 was proposed, which could help improve more than 56% of the construction efficiency compared to common used concrete hollow blocks. In order to study the shear properties and promote its application in building engineering, the shear strength of 10 groups (three specimens for each group) of masonries considering different axial stress level and whether or not to use concrete in the grouting holes were studied, and the failure mode as well as the shear strength of the masonries were analyzed. And then, the calculation formulas for predicting the shear strength of the IHAC masonry were obtained by using the parameter fitting method based on the Coulomb failure theory, which could well reflect the parabolic shaped changing characteristic of the shear strength with the increasing of the axial stress, and the maximum difference was within 18% between the calculated and test results.

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.

scholarly journals Experimental study on the influence of recycled aggregates on the mechanical properties of concrete

2021 ◽  
Vol 283 ◽  
pp. 01033
Author(s):  
Chuangui Li ◽  
Hongkui Zhao ◽  
Jianfeng Wu ◽  
Xiangang Li ◽  
Ya Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Solid Waste ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Cohesive Force ◽  
Recycled Aggregates ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Splitting Strength

Construction solid waste has become an important environmental pollution source in the city, and the treatment and application of construction solid waste has become the focus of attention. Construction waste recycled aggregates have defects such as high water absorption and micro cracks, which affect its extensive application. In order to improve the utilization rate of recycled aggregates, the influence of different replacement rates of recycled aggregates on the mechanical properties of concrete is studied in this paper. The results show that with the increase of replacement rate of recycled aggregates, the 3-day, 7-day and 28-day compressive strength, splitting strength and cohesive force of concrete decrease gradually, but the mechanical properties of concrete decrease slowly at 3 days and 7 days, and decrease obviously at 28 days. Moreover, with the increase of replacement rate of recycled aggregates, the decline trend of mechanical properties is not obvious. Compared with natural aggregate concrete, the 28-day compressive strength, splitting strength and cohesive force of 100% recycled aggregate concrete are reduced by 16.1%, 20.1% and 18.1% respectively, but the mechanical properties meet the requirements of C30 concrete, which provides a reference for engineering application.

scholarly journals Recycled Aggregates Concrete Compressive Strength Prediction Using Artificial Neural Networks (ANNs)

2021 ◽  
Vol 6 (2) ◽  
pp. 17
Author(s):  
Mohamad Ali Ridho B K A ◽  
Chayut Ngamkhanong ◽  
Yubin Wu ◽  
Sakdirat Kaewunruen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Strength Prediction ◽  
Concrete Compressive Strength ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Ann Models

The recycled aggregate is an alternative with great potential to replace the conventional concrete alongside with other benefits such as minimising the usage of natural resources in exploitation to produce new conventional concrete. Eventually, this will lead to reducing the construction waste, carbon footprints and energy consumption. This paper aims to study the recycled aggregate concrete compressive strength using Artificial Neural Network (ANN) which has been proven to be a powerful tool for use in predicting the mechanical properties of concrete. Three different ANN models where 1 hidden layer with 50 number of neurons, 2 hidden layers with (50 10) number of neurons and 2 hidden layers (modified activation function) with (60 3) number of neurons are constructed with the aid of Levenberg-Marquardt (LM) algorithm, trained and tested using 1030 datasets collected from related literature. The 8 input parameters such as cement, blast furnace slag, fly ash, water, superplasticizer, coarse aggregate, fine aggregate, and age are used in training the ANN models. The number of hidden layers, number of neurons and type of algorithm affect the prediction accuracy. The predicted recycled aggregates compressive strength shows the compositions of the admixtures such as binders, water–cement ratio and blast furnace–fly ash ratio greatly affect the recycled aggregates mechanical properties. The results show that the compressive strength prediction of the recycled aggregate concrete is predictable with a very high accuracy using the proposed ANN-based model. The proposed ANN-based model can be used further for optimising the proportion of waste material and other ingredients for different targets of concrete compressive strength.

scholarly journals Effect of Nylon Fiber Addition on the Performance of Recycled Aggregate Concrete

2019 ◽  
Vol 9 (4) ◽  
pp. 767 ◽  
Author(s):  
Seungtae Lee
Keyword(s):  
Mechanical Properties ◽  
Pulse Velocity ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Crushed Stone ◽  
Total Charge ◽  
Test Results ◽  
Aggregate Concrete ◽  
Nylon Fiber

The adhered mortars in recycled aggregates (RA) may lower the performance of the concrete, by for instance reducing its strength and durability, and by cracking. In the present study, the effect of nylon fiber (NF) on the permeability as well as on the mechanical properties of concrete incorporating 100% RA was experimentally investigated. Concrete was produced by adding 0, 0.6 and 1.2 kg/m3 of NF and then cured in water for a predetermined period. Measurements of compressive and split tensile strengths, ultrasonic pulse velocity and total charge passed through concrete were carried out, and the corresponding test results were compared to those of concrete incorporating crushed stone aggregate (CA). In addition, the microstructures of 28-day concretes were examined by using the FE-SEM technique. The test results indicated that recycled coarse aggregate concrete (RAC) showed a lower performance than crushed stone aggregate concrete (CAC) because of the adhered mortars in RA. However, it was obvious that the addition of NF in RAC mixes was much more effective in enhancing the performance of the concretes due to the crack bridging effect from NF. In particular, a high content of NF (1.2 kg/m3) led to a beneficial effect on concrete properties compared to a low content of NF (0.6 kg/m3) with respect to mechanical properties and permeability, especially for RAC mixes.

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.

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.

Shear strength of interfaces in natural and in recycled aggregate concrete

2017 ◽  
Vol 44 (3) ◽  
pp. 212-222
Author(s):  
Shakeel Ahmad Waseem ◽  
Bhupinder Singh
Keyword(s):  
Shear Strength ◽  
Shear Plane ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Failure Envelope ◽  
Interface Shear ◽  
Aggregate Concrete ◽  
Normal Strength ◽  
Strength Models

Shear strength of interfaces in natural aggregate concrete and in recycled aggregate concrete has been investigated using initially uncracked push-off specimens by varying the following parameters: replacement level of the recycled aggregates (0%, 50%, and 100%), concrete grade (normal-strength and medium-strength), and clamping force on the shear plane. Development of truss action for resisting interface shear was indicated by the observed crack patterns in the tested specimens and a truss-based analysis recommended in the literature in combination with a simplified failure envelope for concrete subjected to biaxial stresses has been used for shear strength predictions of the tested specimens. The proposed methodology, which is considered to be more rational than the empirical shear strength models available in the literature was calibrated for both the concrete types and gave conservative and reasonably accurate shear strength predictions for selected experiments taken from the literature.

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.

Investigation of the mechanical properties of concrete containing recycled aggregate and scrap crumb rubber and polypropylene fibers

2020 ◽  
pp. 147776062097750
Author(s):  
Moein Khoshroo ◽  
Ali Akbar Shirzadi Javid ◽  
Nima Rajabi Bakhshandeh ◽  
Mohamad Shalchiyan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Polypropylene Fiber ◽  
Crumb Rubber ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
Mixture Ratio ◽  
Coarse Aggregates

In this study, the effect of using crumb rubber and recycled aggregates on the mechanical properties of concrete has been evaluated as areplacement of fine and coarse aggregates In order to add the admixtures and evaluate their combined effect, 20 different types of concrete mixture ratio were prepared. The results indicated that in those samples containing crumb rubber and recycled aggregates the compressive strength is reduced and adding fiber up to 0.1%. to these concrete samples can improve the compressive strength Also, the tensile strength of the samples mixed with crumb rubber and recycled aggregates were decreased, and with the addition of propylene fiber up to 0.4%. the tensile strength slightly increased Moreover by adding the crumb rubber to the samples the elasticity modulus was reduced but by adding fiber to samples about 0.1% and 0.2.% the modulus of elasticity of concrete in all samples were increased. According to the results, it can be said that using the combination of 5% of crumb rubber as a replacement of fine aggregate, and the combination of 35% of recycled aggregates as a replacement of coarse aggregate, and also by adding 0.1% polypropylene fiber in volumetric percentage of concrete along with adding 7% of micro silica as a replacement of cement led to the best effect on the mechanical properties of concrete.

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