Test to Fly Ash Recycled Concrete under Different Water Cement Ratio

2013 ◽  
Vol 303-306 ◽  
pp. 2606-2610
Author(s):  
Ming Zheng Chen ◽  
Xian Feng Liu ◽  
Lin Qing Huang
Keyword(s):  
Fly Ash ◽  
Performance Test ◽  
Mechanical Performance ◽  
Influence Factors ◽  
Engineering Application ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Solid Foundation

The recovery and utilization to building solid waste is the current hot issues in the construction of towns. In this paper, 30 groups of fly ash recycled concrete test cube were designed and produced, through the mechanical performance test research, we analysised the main influence factors to the strength and performances of fly ash regeneration concrete test cube,such as recycled aggregate category, water cement ratio, the admix proportion of recycled aggregate. The test results would lay a solid foundation for the test research and engineering application of recycled concrete.

Study on the Frost Resistance of Artificial Aggregates Recycled Concrete

2012 ◽  
Vol 509 ◽  
pp. 82-87
Author(s):  
Jin Bang Wang ◽  
Zong Hui Zhou
Keyword(s):  
Elastic Modulus ◽  
Fly Ash ◽  
Silica Fume ◽  
Frost Resistance ◽  
Mechanical Performance ◽  
Recycled Concrete ◽  
Dynamic Elastic Modulus ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw

The recycled concrete was prepared by using the high-strength artificial aggregates. This kind of concrete can be completely regenerated to be cement, and the recycling utilization of the concrete can also be truly realized. The frost resistance and influencing factors of the recycled concrete were studied. The results show that the mechanical performance and frost resistance of artificial aggregates recycled concrete are better than those of the ordinary concrete under the same water/cement ratio condition. When the water/cement ratio is 0.40, the relative dynamic elastic modulus, weight loss and frost durability factor of the recycled concrete are 98.7%, 0.5% and 65.8 after 200 times freeze-thaw cycles. When the fly ash and silica fume were added into the recycled concrete, the frost resistance can be improved. The optimal amounts of fly ash and silica fume are 30% and 15% of cement by weight, respectively. The recycled concrete was prepared with the optimal fly ash and silica fume content, respectively. After 200 times freeze-thaw cycles, the relative dynamic elastic modulus of the recycled concrete are 99.1% and 99.2%, and the weight losses of the recycled concrete are 0.4% and 0.3%, and antifreeze durability coefficient of the recycled concrete are 66.07 and 66.13. Therefore, the recycled concrete with silica fume has better frost resistance performance than that with fly ash as admixture.

Mechanical Performance and Durability of Fly Ash Recycled Aggregate Concretes

2012 ◽  
Vol 538-541 ◽  
pp. 1568-1572
Author(s):  
Valeria Corinaldesi
Keyword(s):  
Fly Ash ◽  
Mechanical Performance ◽  
Point Of View ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Engineering Properties ◽  
Sustainable Construction ◽  
Reinforced Concrete Structure ◽  
Fly Ash Concrete ◽  
Natural Aggregates

According to the concept of sustainable development, the environmental load of a building must be evaluated throughout its life cycle, from design to construction, maintenance or repair, demolition, and rubble disposal. Therefore, from a holistic point of view, sustainable construction means designing a reinforced concrete structure with proper durability during a specified service life. This paper discusses the effect of partial and full replacement of natural aggregates by recycled concrete aggregates (RCA) in a fly ash concrete. Engineering properties and durability performance have been examined for mixtures designed with various proportions of the RCA by mass. Results obtained showed that the addition of RCA lowers concrete performance, but the combined use of RCA and fly ash could allow to achieve adequate engineering properties and durability.

Effect of Admixed Recycled Aggregate on Properties of Recycled Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 743-746
Author(s):  
Ya Jun Zhao ◽  
Ying Gao ◽  
Li Li He
Keyword(s):  
Compressive Strength ◽  
Design Method ◽  
Orthogonal Design ◽  
Plain Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
The Impact

The mixture proportion of recycled concrete was discussed by orthogonal design method. The influence of water-cement ratio, recycled aggregate quantity on workability, cube compressive strength of recycled concrete was analyzed. The experimental results indicated that，Recycled concrete mix proportion design should consider the impact of the water absorption of recycled aggregate. Unit water amount of recycled concrete should be plain concrete unit water consumption and recycled aggregate additional amount of water. Sand ratio should increase in the corresponding ordinary aggregate concrete sand ratio on the basis of 1 to 3 percent. When the water-cement ratio is 0.36 and construction waste content of 40% slag content of 20%, 28d compressive strength of concrete is 48.1MPa, slightly higher than the reference concrete (48.0MPa).

Effect of nanocomposite slurry on strength development of fully recycled aggregate concrete

2021 ◽  
pp. 136943322199248
Author(s):  
Tao Meng ◽  
Song-lin Yu ◽  
Huadong Wei ◽  
Sheng Zhu
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Natural Aggregate ◽  
Enhancement Method

Recycled concrete has been widely used in construction because of the gradual shortage of natural aggregate resources and the large amount of construction waste. In this study, concrete with 100% recycled aggregate was prepared, and its properties, microtopography, and potential enhancement method were investigated. The results indicated that the mechanical properties of the fully recycled aggregate concrete (FRC) were significantly inferior to the natural aggregate concrete. The compressive strength of the FRC with a water-cement ratio of 0.6 was noticeably improved by spraying a nanocomposite slurry on recycled aggregate, whereas this had little influence when the water-cement ratio was 0.3. The compressive strength of the FRC with a water-cement ratio of 0.3 could be improved by mixing with strengthening materials. The best improvement in the compressive strength of the concrete was observed at 28 days because a membrane covered the surface of the aggregate, creating a bond between the aggregate and cement, filling the pores between them, and compacting the concrete. This paper reports a prospective method for improving the properties of FRC, which will promote the application of recycled aggregate in industry.

scholarly journals Mechanical Performance of Concrete Made with Recycled Aggregates from Concrete Pavements

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yancong Zhang ◽  
Lingling Gao ◽  
Wei Bian
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Inhibitory Effect ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Pavements ◽  
Flexural Tensile Strength

This research aims at analysing the mechanical performance of concrete with recycled aggregates from concrete pavements. First, the characteristics of various natural and recycled aggregates used in the concrete were thoroughly analysed. The composition of the recycled aggregates was determined and several physical and chemical tests of the aggregates were performed. In order to evaluate the mechanical performance of recycled concrete, cube compressive strength and flexural tensile strength tests were performed. The effect of recycled aggregates on the strength of recycled concrete is related to the strength of recycled aggregates, the strength of natural aggregates, and the strength of old concrete. The strength of recycled concrete decreases with increasing water-cement ratio. However, due to the water absorption of the recycled aggregate, it has a certain inhibitory effect on the strength reduction. As the replacement rate of recycled aggregates increases, the optimal sand ratio decreases. The sand ratio is controlled between 32% and 38%, which is ideal for recycled concrete. With the increase of fly ash content, the 7 d strength of recycled concrete has decreased to some extent, but the 28 d strength has been slightly improved. In addition, for compressive strength and flexural tensile strength, the optimal content of fly ash is different.

scholarly journals Pore structure and strength of waste fiber recycled concrete

2019 ◽  
Vol 14 ◽  
pp. 155892501987470 ◽  
Author(s):  
Jinghai Zhou ◽  
Tianbei Kang ◽  
Fengchi Wang
Keyword(s):  
Mechanical Properties ◽  
Fractal Dimension ◽  
Pore Structure ◽  
Fiber Length ◽  
Volume Fraction ◽  
Fractal Theory ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio

The pore structure is one of the major factors affecting the mechanical properties of waste fiber recycled concrete. In this article, the pore structure and strength performance of waste fiber recycled concrete are experimentally studied. The design variables are water–cement ratio, recycled aggregate replacement rate, waste fiber length, and volume fraction of waste fibers. The pore structure characteristic parameters of waste fiber recycled concrete are investigated using mercury intrusion porosimetry test and fractal theory. The complex distribution of pore structure in space is quantitatively described by fractal dimension, and the pore structure is comprehensively evaluated. The results show that the water–cement ratio has the largest influence on the pore structure, and the fiber length has the least influence. The optimum volume fraction of waste fibers is 0.12%. There is an obvious linear relationship between the pore volume fractal dimension and strength. With the increase in the fractal dimensions, the compressive and splitting tensile strengths increase. Macroscopic mechanical properties of waste fiber recycled concrete can be predicted by the pore structure.

scholarly journals MECHANICAL PERFORMANCE OF RECYCLED AGGREGATE SELF-CONSOLIDATING CONCRETE COLUMN

2021 ◽  
Vol 27 (3) ◽  
pp. 188-202
Author(s):  
Feng Yu ◽  
Chaochao Feng ◽  
Shilong Wang ◽  
Wei Huang ◽  
Yuan Fang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Mechanical Performance ◽  
Engineering Application ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Conventional Concrete ◽  
Self Consolidating Concrete ◽  
Stress Strain Relation

The utilization of recycled concrete aggregate (RCA) can reduce the environmental impact and decreases the cost of concrete. In this study, a comprehensive assessment of self-consolidating concrete (SCC) using RCA as partial or total replacement of coarse aggregate was conducted. Recycled concrete aggregate self-consolidating concrete (RCA-SCC) mixtures with varied water-to-cement (W/C) ratios (0.28–0.46), sand-to-aggregate (S/A) ratios (48–52%), fly ash (FA) contents (20–40%), RCA replacement ratios (0–100%), and water reducer contents (0–1.5%) were designed and tested. 5 groups of the RCA-SCC columns with different W/C and replacement ratios of RCA were also investigated. The slump flow, the J-ring flow and the cubic compressive strength, and the compressive behaviors of the RCA-SCC columns were studied. Results indicated that W/C ratio was the dominant parameter in RCA-SCC mixture, and the failure modes of the RCA-SCC columns were similar to those of the conventional concrete columns. Based on the experimental results, the mechanical performance of RCA-SCC columns was evaluated quantitatively, and a stress–strain relation model for predicting the axial compressive behavior of RCA-SCC column was proposed. This study will provide a reference for the engineering application of the environment-friendly SCC using RCA that are derived from tested or returned concretes with better performance.

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

2009 ◽  
Vol 620-622 ◽  
pp. 255-258 ◽  
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.

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