Superplasticizer’s efficiency on the mechanical properties of recycled aggregates concrete: Influence of recycled aggregates composition and incorporation ratio

2017 ◽  
Vol 153 ◽  
pp. 129-138 ◽  
Author(s):  
M. Bravo ◽  
J. de Brito ◽  
L. Evangelista ◽  
J. Pacheco
Keyword(s):  
Mechanical Properties ◽  
Recycled Aggregates ◽  
Incorporation Ratio

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.

Effect of mixed recycled aggregates on mechanical properties of recycled concrete

2015 ◽  
Vol 67 (5) ◽  
pp. 247-256 ◽  
Author(s):  
Desirée Rodríguez-Robles ◽  
Julia García-González ◽  
Andrés Juan-Valdés ◽  
Julia Ma Morán-del Pozo ◽  
M. Ignacio Guerra-Romero
Keyword(s):  
Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Mixed Recycled Aggregates

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.

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.

Influence of rice husk–bark ash on mechanical properties of concrete containing high amount of recycled aggregates

2008 ◽  
Vol 22 (8) ◽  
pp. 1812-1819 ◽  
Author(s):  
Weerachart Tangchirapat ◽  
Rak Buranasing ◽  
Chai Jaturapitakkul ◽  
Prinya Chindaprasirt
Keyword(s):  
Mechanical Properties ◽  
Rice Husk ◽  
Recycled Aggregates ◽  
Rice Husk Bark Ash

Enhancement on Mechanical Properties of Hybrid Concrete by Incorporating Fibers with Different Geometrical Dimensions

2011 ◽  
Vol 243-249 ◽  
pp. 5941-5945
Author(s):  
Ya Fang Zhang ◽  
Lin Li ◽  
Hao Liu
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Flexural Strength ◽  
Enhancement Effect ◽  
Polypropylene Fibers ◽  
Hybrid Fiber ◽  
Meso Level ◽  
Fiber Concrete ◽  
Geometrical Dimensions ◽  
Incorporation Ratio

With numerical modeling in meso level, impaction of incorporating polypropylene fibers with two different geometry dimensions on flexural strength and toughness of hybrid fiber concrete has been studied in this paper. Mechanism of such hybrid fiber reinforcement has also been analyzed. The results show that hybrid of fibers with different geometric dimensions would bring about synergy, thus fiber enhancement effect could be demonstrated. Furthermore, the closer the incorporation ratio of these two kinds fibers are to each other, the more evident the enhancement will be produced. The most optimized hybrid ratio is in between 2:1 and 1:1.

scholarly journals Impacts of Casting Scales and Harsh Conditions on the Thermal, Acoustic, and Mechanical Properties of Indoor Acoustic Panels Made with Fiber-Reinforced Alkali-Activated Slag Foam Concretes

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 825 ◽  
Author(s):  
Mastali Mohammad ◽  
Kinnunen Paivo ◽  
Karhu Marjaana ◽  
Abdollahnejad Zahra ◽  
Korat Lidija ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Comparative Study ◽  
Sound Absorption ◽  
Acoustic Properties ◽  
Recycled Aggregates ◽  
Fiber Reinforced ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Harsh Conditions ◽  
Alkali Activated

This paper presents experimental results regarding the efficiency of using acoustic panels made with fiber-reinforced alkali-activated slag foam concrete containing lightweight recycled aggregates produced by using Petrit-T (tunnel kiln slag). In the first stage, 72 acoustic panels with dimension 500 × 500 × 35 mm were cast and prepared. The mechanical properties of the panels were then assessed in terms of their compressive and flexural strengths. Moreover, the durability properties of acoustic panels were studied using harsh conditions (freeze/thaw and carbonation tests). The efficiency of the lightweight panels was also assessed in terms of thermal properties. In the second stage, 50 acoustic panels were used to cover the floor area in a reverberation room. The acoustic absorption in diffuse field conditions was measured, and the interrupted random noise source method was used to record the sound pressure decay rate over time. Moreover, the acoustic properties of the panels were separately assessed by impedance tubes and airflow resistivity measurements. The recorded results from these two sound absorption evaluations were compared. Additionally, a comparative study was presented on the results of impedance tube measurements to compare the influence of casting volumes (large and small scales) on the sound absorption of the acoustic panels. In the last stage, a comparative study was implemented to clarify the effects of harsh conditions on the sound absorption of the acoustic panels. The results showed that casting scale had great impacts on the mechanical and physical properties. Additionally, it was revealed that harsh conditions improved the sound properties of acoustic panels due to their effects on the porous structure of materials.

The Recycled Aggregates with Surface Treatment by Pozzolanics

2005 ◽  
Vol 287 ◽  
pp. 63-68 ◽  
Author(s):  
Jae Jun Kim ◽  
Sang Heum Youn ◽  
M.J. Cho ◽  
H.T. Shin ◽  
Jeong Bae Yoon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Surface Treatment ◽  
Water Absorption ◽  
Recycled Aggregates ◽  
Scanning Electron Micrographs ◽  
Cement Mortars ◽  
Pozzolanic Materials ◽  
Adsorption Treatment ◽  
Scanning Electron

To improve the mechanical properties of concretes containing recycled aggregates, pozzolanic materials were used to decrease the porosity of the recycled aggregates. These pozzolanic materials were adhered on the surface of recycled aggregates and closed the open pores so that the water absorption was decreased 1~2% as the amount of adsorption was increased. Compressive strength of cement mortars and concretes using surface treated recycled aggregates reaches above 95% of the strength of its natural counterparts. Investigation of the microstructures using the scanning electron micrographs showed the formation of dense interface after the adsorption treatment of pozzolanics to recycled aggregates.

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