Compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete incorporating class-F fly ash

2006 ◽  
Vol 21 (4) ◽  
pp. 130-136 ◽  
Author(s):  
Kou Shicong ◽  
C S Poon
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Chloride Ion ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Chloride Ion Penetration ◽  
Class F Fly Ash

scholarly journals Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

2015 ◽  
Vol 18 (2) ◽  
pp. 427-440 ◽  
Author(s):  
Rui Vasco Silva ◽  
Jorge de Brito ◽  
Rui Neves ◽  
Ravindra Dhir
Keyword(s):  
Chloride Ion ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Chloride Ion Penetration ◽  
Ion Penetration

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.

Influence of Recycled Aggregate Defects on the Durability of Recycled Aggregate Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 173-182 ◽  
Author(s):  
Gai Fei Peng ◽  
Juan Yang ◽  
Jing Yan Wang
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Sulfuric Acid Solution ◽  
Chloride Ion ◽  
Penetration Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Penetration ◽  
Aggregate Concrete ◽  
Chloride Ion Penetration

An experimental investigation was conducted on the durability of recycled aggregate concretes with the water to binder ratios of 0.26 and 0.60, including chloride ion penetration resistance test, freezing-thawing resistance test and water penetration resistance. Natural aggregate, recycled aggregate untreated and recycled aggregate treated by sulfuric acid solution, were employed. Results indicated that, 3 mol/L acid concentration and the 7 days soaking duration was the optimum to remove the attached mortars in recycled aggregate, and its removal rate could reach to 90.8%. Water penetration resistance, chloride ion penetration resistance and freezing-thawing resistance of concrete with 0.26 W/B was superior to that of concrete with 0.60 W/B. The more pores in the internal of concrete with 0.60 W/B could be attributed to that. Durability of recycled aggregate concrete, incorporating recycled aggregate treated by sulfuric acid solution, was improved. In particular, the improvement in recycled high strength concrete was significant.

scholarly journals Experimental study on mechanical properties and microstructures of steel fiber-reinforced fly ash-metakaolin geopolymer-recycled concrete

2021 ◽  
Vol 60 (1) ◽  
pp. 578-590
Author(s):  
Zhong Xu ◽  
Zhenpu Huang ◽  
Changjiang Liu ◽  
Xiaowei Deng ◽  
David Hui ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Steel Fiber ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Mix Proportion ◽  
Optimal Mix

Abstract Geopolymer cementitious materials and recycled aggregate are typical representatives of material innovation research in the engineering field. In this study, we experimentally investigated a method to improve the performance of geopolymer-recycled aggregate concrete (GRAC). The recycled concrete aggregates and steel fiber (SF), fly ash (FA), metakaolin (MK), and sodium silicate solution were used as the main raw materials to prepare fiber-reinforced geopolymer-recycled aggregate concrete (FRGRAC). First, the orthogonal test was carried out to study the GRAC, and the optimal mix proportion was found. Second, building on the optimal mix proportion, the effects of the SF content on the slump, 7 and 28 days compressive strength, tensile strength, and flexural strength of FRGRAC were further studied. Finally, the microscopic mechanism of FRGRAC was studied by scanning electron microscopy (SEM). The study results indicate that the slump continues to decrease as the fiber content increases, but the compressive strength, tensile strength, and flexural strength increase to a certain extent. Through SEM analysis, it is found that SF restrains the development of cracks and improves the strength of concrete.

scholarly journals Application of X-Ray Computed Tomography in Monitoring Chloride Ion Penetration Paths in Recycled Aggregate Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Yuan Zuo ◽  
Bing Qi ◽  
Jianming Gao ◽  
Weibin Li
Keyword(s):  
Computed Tomography ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
X Ray ◽  
Chloride Ion Penetration ◽  
X Ray Computed ◽  
Ion Penetration

The penetration paths of chloride ions in recycled aggregate concrete (RAC) are of significant interest and have not been well studied previously. This study used X-ray computed tomography (X-CT) as a novel approach to investigate chloride ion penetration paths in RAC. The results indicate that X-CT can be used for the constant monitoring of chloride ion penetration paths in RAC, and the influence of mix proportions on the chloride ion penetration can be understood through the X-CT visualization.

scholarly journals Effect of Mineral Admixtures on the Performance of Low-Quality Recycled Aggregate Concrete

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.

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