Experimental Study of Compressive Properties and Environmental Impact of Recycled Aggregate

As the main component of fiber-reinforced recycled aggregate concrete, the properties of recycled aggregate determine whether recycled aggregate concrete can be used in engineering applications. To study the compressive properties and environmental impact of recycled aggregate, large-scale indoor compression tests were carried out on recycled aggregate under different moisture contents, concrete aggregate ratios, dry-wet cycles, and loads. The results showed that the crushing rate and settlement first increased and then decreased upon increasing the moisture content. Upon increasing the concrete aggregate ratio, the settlement continuously decreased, and the crushing rate decreased from 157.2 to 82.5%. Upon increasing the number of dry-wet cycles, the settlement continued to increase to an upper limit of about 17.5%, and the crushing rate increased to 35%. Upon increasing the load, the settlement and crushing rate of the aggregate increased. These results show that the effects of aggregate ratio, moisture content, and dry-wet cycles on settlement were caused by crushing the aggregate. Based on this, a formula was constructed to predict the final settlement of reclaimed aggregate. The leaching amount of Cr in recycled aggregate was 0.0175–0.0375 mg/L under normal conditions, but under extreme conditions, the leaching amount of some sampling points was greater than in the standard requirements. This means that recycled aggregate may pose environmental risks that should be mitigated during use. Recycled aggregate can be used to construct sponge city storage and reuse facilities, as well as fiber-reinforced recycled aggregate concrete, but its sources need to be determined to ensure that it does not pose environmental risks.

Download Full-text

On the Structural Performance of Recycled Aggregate Concrete Columns with Glass Fiber-Reinforced Composite Bars and Hoops

Polymers ◽

10.3390/polym13091508 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1508

Author(s):

Ali Raza ◽

Ahmad Rashedi ◽

Umer Rafique ◽

Nazia Hossain ◽

Banjo Akinyemi ◽

...

Keyword(s):

Glass Fiber ◽

Compressive Loading ◽

Reinforcement Ratio ◽

Recycled Aggregate Concrete ◽

Experimental Results ◽

Recycled Aggregate ◽

Fiber Reinforced ◽

Aggregate Concrete ◽

Gfrp Bars ◽

Glass Fiber Reinforced

Structural members comprising geopolymer recycled aggregate concrete (RAC) reinforced with glass fiber-reinforced polymer (GFRP) bars have not been investigated appropriately for axial compressive loading cases. The present study addresses this knowledge gap by evaluating the structural efficiency of GFRP-reinforced geopolymer recycled aggregate concrete (GGRAC)-based members subjected to axial compressive loading. A total of nine compressive members (250 mm in cross-section and 1150 mm in height) were constructed to examine the effect of the number of longitudinal GFRP bars and the vertical spacing of transverse GFRP hoops/ties. The experimental results portrayed that the ductility of GGRAC compressive members improved with the reduction in the pitch of GFRP hoops. The axial load-carrying capacity (LCC) of GGRAC compressive members increased by increasing the number of GFRP bars up to eight (corresponding to a reinforcement ratio of 2.11%) while it decreased by using ten longitudinal GFRP bars (corresponding to a reinforcement ratio of 2.65%). Additionally, an empirical model was suggested to predict the axial LCC of GGRAC compressive members based on a large amount of experimental data of similar members. The experimental results and related theoretical predictions substantially prove the applicability and accuracy of the proposed model. The proposed column represents a feasible structural member in terms of material availability and environmental sustainability.

Download Full-text

Production of sustainable and structural fiber reinforced recycled aggregate concrete with improved fracture properties: A review

Journal of Cleaner Production ◽

10.1016/j.jclepro.2020.123832 ◽

2021 ◽

Vol 279 ◽

pp. 123832 ◽

Cited By ~ 2

Author(s):

Wisal Ahmed ◽

C.W. Lim

Keyword(s):

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Fiber Reinforced ◽

Aggregate Concrete ◽

Fracture Properties

Download Full-text

Compressive stress–strain behavior of steel fiber reinforced-recycled aggregate concrete

Cement and Concrete Composites ◽

10.1016/j.cemconcomp.2013.11.006 ◽

2014 ◽

Vol 46 ◽

pp. 65-72 ◽

Cited By ~ 105

Author(s):

Jodilson Amorim Carneiro ◽

Paulo Roberto Lopes Lima ◽

Mônica Batista Leite ◽

Romildo Dias Toledo Filho

Keyword(s):

Compressive Stress ◽

Steel Fiber ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Fiber Reinforced ◽

Stress Strain ◽

Aggregate Concrete ◽

Strain Behavior

Download Full-text

Recycling of Waste Concrete and Fly Ash for Recycled Aggregate Concrete: Fundamental Characteristics Evaluation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.620-622.255 ◽

2009 ◽

Vol 620-622 ◽

pp. 255-258 ◽

Cited By ~ 1

Author(s):

Cheol Woo Park

Keyword(s):

Fly Ash ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Experimental Program ◽

Concrete Aggregate ◽

Fine Aggregate ◽

Recycled Concrete Aggregate ◽

Aggregate Concrete ◽

Waste Concrete

As the amount of waste concrete has been increased and recycling technique advances, this study investigates the applicability of recycled concrete aggregate for concrete structures. In addition fly ash, the industrial by-product, was considered in the concrete mix. Experimental program performed compressive strength and chloride penetration resistance tests with various replacement levels of fine recycled concrete aggregate and fly ash. In most case, the design strength, 40MPa, was obtained. It was known that the replacement of the fine aggregate with fine RCA may have greater influence on the strength development rather than the addition of fly ash. It is recommended that when complete coarse aggregate is replaced with RCA the fine RCA replacement should be less than 60%. The recycled aggregate concrete can achieve sufficient resistance to the chloride ion penetration and the resistance can be more effectively controlled by adding fly ash. It I finally conclude that the recycled concrete aggregate can be successfully used in the construction field and the recycling rate of waste concrete and flay ash should be increased without causing significant engineering problems.

Download Full-text