scholarly journals Mechanical and Damping Properties of Recycled Aggregate Concrete Modified with Air-Entraining Agent and Polypropylene Fiber

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2004 ◽  
Author(s):  
Chonggang Zhou ◽  
Xingwang Pei ◽  
Wenlong Li ◽  
Yijun Liu
Keyword(s):  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Favorable Effect ◽  
Damping Properties ◽  
Aggregate Concrete ◽  
Negative Effect

In this study, recycled aggregate concrete (RAC) modified with polypropylene fiber (PP) and air-entraining agent (AGA) was prepared, and the effects of PP and AGA on the static (compressive strength, Young’s modulus, and splitting tensile strength) and dynamic properties (dynamic modulus of elasticity and damping ratio) of RAC were investigated. The experimental results showed that the addition of an AGA and PP had a favorable effect on the damping ratio of the concrete, however, the addition of the AGA had a slightly negative effect on the mechanical performance of the concrete. The AGA and PP contents required to achieve the optimum damping ratio of the concrete with the least reduction in the mechanical performance were 0.02% and 0.10%, respectively. Furthermore, the addition of AGA was more effective than that of PP in improving the damping property of the concrete.

scholarly journals Experimental study on the compressive strength, damping and interfacial transition zone properties of modified recycled aggregate concrete

2019 ◽  
Vol 6 (12) ◽  
pp. 190813
Author(s):  
Bin Lei ◽  
Huajian Liu ◽  
Zhimin Yao ◽  
Zhuo Tang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Transition Zone ◽  
Loss Factor ◽  
Steel Fibre ◽  
Interfacial Transition Zone ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Damping Properties ◽  
Aggregate Concrete

At present, many modification methods have been proposed to improve the performance of recycled aggregate concrete (RAC). In this study, tests on the compressive strength and damping properties of modified RAC with the addition of different proportions of recycled coarse aggregate (RCA) (0, 50, 100%), rubber powder (10, 15, 20%), steel fibre (5, 7.5, 10%) and fly ash (15, 20, 5%) are carried out. To elucidate the effect of the modification method on the interfacial transition zone (ITZ) performance of RAC, model ITZ specimens are used for push-out tests. The results show that when the replacement rate of RCA reaches 100%, the loss factor of the RAC is 6.0% higher than that of natural aggregate concrete; however, the compressive strength of the RAC decreases by 22.6%. With the addition of 20% rubber powder, the damping capacity of the modified RAC increases by 213.7%, while the compressive strength of the modified RAC decreases by 47.5%. However, with the addition of steel fibre and fly ash, both the compressive strength and loss factor of the RAC specimens increase. With a steel fibre content of 10 wt%, the compressive strength and loss factor of the RAC increase by 21.9% and 15.2%, respectively. With a fly ash content of 25 wt%, the compressive strength and loss factor of the RAC increase by 8.6% and 6.9%, respectively. This demonstrates that steel fibre and fly ash are effective in improving both the damping properties and compressive strength of RAC, and steel fibre is more effective than fly ash. Two methods were used for modification of the RAC: reinforcing the RCA through impregnation with a 0.5% polyvinyl alcohol (PVA) emulsion and nano-SiO 2 solution, and strengthening the RAC integrally through the addition of fly ash as an admixture. Both of these techniques can improve the ITZ bond strength between the RAC and new mortar. Replacing 10% of the cement with fly ash in the new mortar is shown to be the best method to improve the ITZ strength.

scholarly journals Dynamic Characteristics and Chloride Resistance of Basalt and Polypropylene Fibers Reinforced Recycled Aggregate Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Dong Lu ◽  
Hui Cao ◽  
Qiangru Shen ◽  
Yue Gong ◽  
Cheng Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Damping Ratio ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Void Content ◽  
Polypropylene Fibers ◽  
Aggregate Concrete ◽  
Chloride Resistance ◽  
Air Void ◽  
Air Void Content

Fiber polymer has been extensively used to improve the mechanical properties and durability of concrete. However, the studies of the effect of fiber polymer on the dynamic performance of recycled aggregate concrete (RAC) is still very limited. In this study, we prepared two types of RAC formulations: RAC reinforced with basalt fibers (BFs) and RAC reinforced with polypropylene fibers (PPs), and compared the effects of fiber types and contents on the air void content, workability (slump), mechanical properties (compressive and flexural strength), dynamic characteristics (dynamic modulus of elasticity and damping ratio), and chloride resistance of RAC. The experimental results showed that the air void content and slump value decreased with the increase of replacement percentage of RCA and fiber contents. Adding PPs provided a more negative effect on the slump of RAC than BFs. The mixtures containing 0.2% PPs and BFs both obtained the highest flexural strength. The addition of PPs was more effective than BFs in improving the damping ratio of RAC, and the mixtures containing 0.3% PPs and BFs both obtained the highest damping ratio. Compared to the RAC without addition of fiber, the charge passed of specimen with addition of PPs approximately increased by 45%, while the specimen with addition of BFs approximately increased by 30%, when the fiber content was 0.3%. This study demonstrates the potential of using fiber to promote the dynamic properties of RAC.

Mechanical properties of recycled aggregate concrete containing crumb rubber and polypropylene fiber

2019 ◽  
Vol 225 ◽  
pp. 983-996 ◽  
Author(s):  
F.M. Zahid Hossain ◽  
Md. Shahjalal ◽  
Kamrul Islam ◽  
Mohammad Tiznobaik ◽  
M. Shahria Alam
Keyword(s):  
Mechanical Properties ◽  
Polypropylene Fiber ◽  
Crumb Rubber ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete

Evaluation of the mechanical performance of M25 grade recycled aggregate concrete

2020 ◽  
Vol 491 ◽  
pp. 012034
Author(s):  
B S Dhanya ◽  
Bino I Koshy ◽  
K V Jisha ◽  
Aisu Jayamohanan ◽  
Neethu Mathew
Keyword(s):  
Mechanical Performance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete

Carbonation Behavior of Recycled Aggregate Concrete under Loading

2011 ◽  
Vol 250-253 ◽  
pp. 779-782 ◽  
Author(s):  
Ping Hua Zhu ◽  
Xin Jie Wang ◽  
Jin Cai Feng
Keyword(s):  
Fly Ash ◽  
Detrimental Effect ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Loading Level ◽  
Natural Aggregate ◽  
Concrete Mixtures ◽  
Carbonation Resistance ◽  
Negative Effect

A study on carbonation resistance of recycled aggregate concrete (RAC) subjected to different loading level was carried out. Three series of concrete mixtures were prepared with loading level of 0.5, 0.8, and 1.2 of ultimately tensive strength of concrete. The coarse recycled aggregate was used as 30%, 60% and 90% replacements of coarse natural aggregate and fine recycled aggregate as 10%, 20%, and 30% replacements of fine natural aggregate. Moreover, the fly ash and slag were employed as 15%, 25%, and 35% addition of cement. Although the action of the tensile stress had a negative effect on the carbonation resistance of RAC, it was found that the addition of fly ash and slag was able to mitigate this detrimental effect. The carbonation depth would increase with an increasing loading level and reduce when increasing the sand ratio.

scholarly journals Dynamic Compressive Strength of Recycled Aggregate Concrete

2021 ◽  
Vol 8 ◽  
pp. 56-61
Author(s):  
Shamsoon Fareed ◽  
Asad-ur-Rehman Khan ◽  
Samra Masood
Keyword(s):  
Dynamic Properties ◽  
Compressive Loading ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Maximum Height ◽  
Environmental Preservation ◽  
Aggregate Concrete ◽  
Drop Hammer ◽  
Static Mechanical

Over the years the construction waste has enormously increased, this may be attributed to different factors such as (i) demolition (ii) accidents (iii) impact loads (iv) earthquakes. These activities have caused an increasing burden on already exhausted waste management system globally. As a result, the concrete waste produced in a large quantity has become a major issue to manage due to limited landfill sites. Therefore, the recycling of waste concrete can prove to be beneficial and necessary for the environmental preservation and effective utilization of natural resources. Number of studies have been conducted to study the static mechanical properties of recycled aggregate concrete; however, limited test data has been published which focused on the dynamic properties of the concrete prepared with recycled coarse aggregates. Therefore, in this investigation aim was to study the behavior of recycled aggregates concrete under increasing dynamic compressive loading. For this purpose, cylindrical specimens having a diameter of 100 mm and height of 200 mm were used. These specimens have been prepared with constant concrete mix ratio, having varying percentages of RA such as 0%, 30%, and 50% 70 % and 100%. The dynamic compressive behaviour was studied by using drop hammer system. The height drop hammer system consist of a frame having a maximum height of 15ft. Firstly, three samples (1, 1R, 2R) from each percentage replacement (0%, 30%, 50%, 70% and 100%) were tested on six different velocities of 2.44m/s, 3.45m/s, 4.23m/s, 4.89m/s, 5.46m/s and 7.45m/s with varying strain rates of 12.04/s, 17.00/s, 20.83/s, 24.08/s, 26.89/s and 36.73/s respectively. Weight of the drop hammer was 10 kg. Based on the detailed experimental investigation, it was found that the behaviour of the recycled aggregate concrete under dynamic loading differ significantly from the static loading.

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