Research on the Influence of Amount of Fly Ash and Recycled Coarse Aggregate to the Performance of Recycled Concrete

2019 ◽  
Vol 08 (07) ◽  
pp. 1125-1132
Author(s):  
嘉诚 李
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Coarse Aggregate

Microscopic Mechanism Study on Carbonation Resistance of Recycled Aggregate Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1001-1006 ◽  
Author(s):  
Hai Feng Yang ◽  
Zhi Heng Deng ◽  
Xue Liang Li
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Concrete Carbonation ◽  
Carbonation Resistance

24 100mm × 100mm × 300mm recycled concrete prisms and 96 150mm × 150mm × 150mm cubes are completed in this paper.The relationships of the carbonation depth in each carbonation age with replacement rate of recycled coarse aggregate and fly ash is studied; The SEM is used to observe the interface structure of recycled coarse aggregate concrete and compared with ordinary concrete, and finally,a recycled concrete carbonation model is proposed. The results showed that: the substitution of recycled coarse aggregate and fly ash cut down the recycled concrete carbonation resistance significantly, which are related with the replacement rate; the content of Ca(OH)2 in the recycled aggregate concrete decreased ,also there are obvious interface transition zone between the recycled coarse aggregate and the new cement;obvious cracks and large voids are exist before the recycled aggregate concrete is loaded, which lead directly to lower carbonation resistance of the recycled concrete.

Flexural properties of steel fiber types and reinforcement ratio for high-strength recycled concrete beams

2017 ◽  
Vol 20 (10) ◽  
pp. 1512-1522 ◽  
Author(s):  
Hai-Long Zhang ◽  
Chang-Chun Pei
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Crack Width ◽  
Coarse Aggregate ◽  
Steel Fiber ◽  
High Strength ◽  
Recycled Concrete ◽  
Steel Fibers ◽  
Flexural Properties ◽  
Recycled Coarse Aggregate

This article took fly ash and silica fume as cementing materials to replace part of cement and took recycled coarse aggregate to replace part of gravel to mix plain concrete and studied the flexural properties of the beams with high-strength steel fiber–recycled concrete by changing the types of steel fiber and reinforcement ratio. The results showed that fly ash and silica fume could improve strength and flexural capacity of the recycled concrete beam by filling micro-cracks of recycled coarse aggregate and reduce the development speed of deflection and crack width of the test beam. Steel fibers could significantly slow the development of deflection and crack width of the beams with high-strength recycled concrete, and the difference in end-structure could increase the flexural capacity of the beams in varying degrees. The article put forward theory of improving the bearing capacity of the beam with three kinds of steel fibers by introducing the influence factor of steel fiber end-structure.

Experimental Study on Anti-Permeability of Active Admixture Recycled-Concrete

2013 ◽  
Vol 438-439 ◽  
pp. 121-124
Author(s):  
Ai Jiu Chen ◽  
Xiao Pei Sun ◽  
Fen Yang
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Polypropylene Fiber ◽  
Recycled Concrete ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Recycled Coarse Aggregate ◽  
Slag Powder ◽  
Optimum Proportion ◽  
Active Admixture

Active admixture recycled-concrete (AARC) is one of green high performance concretes, which took active admixture and fly ash into recycled concrete to replace part of cement. This paper researches the relationship of seepage resistance grade and chloride diffusion coefficient of recycled concrete by the regressive analysis of experimental data from NEL and gradually pressure method. The mufti-factor (slag powder, fly ash, air-entraining agent, polypropylene fiber, recycled coarse aggregate) and multi-level experiments of anti-permeability of concrete were carried out by orthogonal experiment method, and the optimum proportion of concrete is determined. The results show that seepage resistance grade of 16 groups AARC all reached W13, and chloride diffusion coefficient was between 0.5~1×10-8cm2/s, the permeability grade is IV. The impermeability of the AARC is excellent. The rate of recycled coarse aggregate and slag powder were the most important factors for the impermeability properties of concrete, the optimum proportion of concrete was 10% slag powder, 20% fly ash, 1/10000 air-entraining agent, 1.0 kg/m3 polypropylene fiber and 40% recycled coarse aggregate.

scholarly journals Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

2020 ◽  
Vol 12 (24) ◽  
pp. 10544
Author(s):  
Chunhong Chen ◽  
Ronggui Liu ◽  
Pinghua Zhu ◽  
Hui Liu ◽  
Xinjie Wang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Total Porosity ◽  
Recycled Concrete ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Carbonation Resistance ◽  
Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

scholarly journals Study on the Effect of Recycled Coarse Aggregate on the Shrinkage Performance of Green Recycled Concrete

2021 ◽  
Vol 13 (23) ◽  
pp. 13200
Author(s):  
Yang Yu ◽  
Peihan Wang ◽  
Zexin Yu ◽  
Gongbing Yue ◽  
Liang Wang ◽  
...  
Keyword(s):  
Primary Particle ◽  
Coarse Aggregate ◽  
Cementitious Material ◽  
Recycled Concrete ◽  
Low Carbon ◽  
Replacement Ratio ◽  
Recycled Coarse Aggregate ◽  
Shrinkage Property ◽  
Low Carbon Emission

Shrinkage property is a significant indicator of the durability of concrete, and the shrinkage of green recycled concrete is particularly problematic. In this paper, construction waste was crushed and screened to generate simple-crushed recycled coarse aggregate (SCRCA). The SCRCA was then subjected to particle shaping to create primary particle-shaped recycled coarse aggregate (PPRCA). On this basis, the PPRCA was particle-shaped again to obtain the secondary particle-shaped recycled coarse aggregate (SPRCA). Under conditions where the dosage of cementitious material is 300 kg/m3 and the sand rate is 38%, a new high-belite sulphoaluminate cement (HBSAC) with low carbon emission and superior efficiency was used as the basic cementitious material. Taking the quality of recycled coarse aggregate (SCRCA, PPRCA, and SPRCA) and the replacement ratio (25%, 50%, 75%, and 100%) as the influencing factors to prepare the green recycled concrete, the workability and shrinkage property of the prepared concrete were analyzed. The results show that the water consumption of green recycled concrete decreases as the quality of the recycled coarse aggregate (RCA) increases and the replacement ratio decreases, provided that the green recycled concrete achieves the same workability. With the improvement of RCA quality and the decrease of replacement ratio, the shrinkage of recycled concrete decreases. The shrinkage performance of green recycled concrete configured with the SPRCA completely replacing the natural coarse aggregate (NCA) is basically the same as that of the natural aggregate concrete (NAC).

scholarly journals Performance of Recycled Concrete Aggregate in Self Compacting Concrete

2018 ◽  
Vol 7 (3.35) ◽  
pp. 1
Author(s):  
T. V. Arul Prakash ◽  
Dr. M. Natarajan ◽  
Dr. T. Senthil Vadivel ◽  
K. Vivek
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Self Compacting Concrete ◽  
Fly Ash Concrete ◽  
Local Construction ◽  
Class F Fly Ash ◽  
Strength And Durability

This article presents the influence of the Recycled Concrete Aggregate (RCA) on the mechanical properties of self-compacting fly ash concrete (M30 Grade). The RCA from local construction demolition site were employed as a replacement for natural coarse aggregate (0% - 30%) in self-compacting concrete (SCC). The Viscosity modifying material used in this study was Class F fly ash. The results indicate that recycled concrete aggregate can be replaced by an optimal 25% replacement percentage in the manufacture of SCC without significantly affecting strength and durability.  

scholarly journals Seismic Performance of Recycled Concrete Filled Circular Steel Tube Columns

2020 ◽  
Vol 7 ◽  
Author(s):  
Dingyi Xu ◽  
Zongping Chen ◽  
Chunheng Zhou
Keyword(s):  
Seismic Performance ◽  
Coarse Aggregate ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Recycled Concrete ◽  
Load Range ◽  
Equivalent Viscous Damping ◽  
Displacement Ductility ◽  
Recycled Coarse Aggregate ◽  
Circular Steel Tube

This study was conducted to experimentally investigate the behavior of recycled concrete-filled circular steel tube (RCFST) columns subjected to cyclic loading. Ten specimens were prepared and tested. Four parameters were used to characterize seismic behavior: the replacement percentage of recycled coarse aggregate, slenderness ratio, axial compression level, and steel ratio. A novel calculation method for the bearing capacity for RCFST columns is established. The failure processes and modes of RCFST columns are found to be similar to normal concrete-filled steel tube columns. Varying the replacement percentage of recycled coarse aggregate has little effect on the hysteresis curves of the RCFST columns. The RCFST columns also show seismic performance similar to that of concrete-filled steel tubes. The displacement ductility of all specimens is larger than 3.0 and the equivalent viscous damping coefficients corresponding to the ultimate load range from 0.305 to 0.460.

Experimental Study on Flexural Behaviors of Steel Reinforced Recycled Coarse Aggregate Concrete Beams

2012 ◽  
Vol 166-169 ◽  
pp. 1614-1619 ◽  
Author(s):  
Wen Yue Qin ◽  
Yu Liang Chen ◽  
Zong Ping Chen
Keyword(s):  
Bearing Capacity ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Recycled Concrete ◽  
Flexural Behavior ◽  
Aggregate Concrete ◽  
Strength Grade ◽  
Recycled Coarse Aggregate ◽  
The Impact

In order to reveal the flexural behavior of normal section of steel reinforced recycled coarse aggregate concrete beams，6 steel reinforced recycled concrete beams were designed for flexural test，the study mainly considered the impact of coarse aggregate replacement rates and concrete strength grade two changing parameters on the flexural behavior of steel reinforced recycled coarse aggregate concrete beams. Through this test, the whole mechanical process、crack distribution and failure behavior of this kind of specimens were observed, and obtained the stress-strain distribution curves、the ultimate bearing capacity and load-displacement curves parameters. Based on the study measurement data, deeply analyzed the impact of coarse aggregate replacement rates and concrete strength grade on the flexural behavior of steel reinforced recycled coarse aggregate concrete beams. The result shows that: steel reinforced recycled coarse aggregate concrete beams’ failure pattern was similar to normal SRC beams, during loading process the section strain agreed with the plane-section assumption, and the beams have good bearing capacity and deformation performance.

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