Comparative study of tensile tests based on Hopkinson bar for recycled aggregate concrete

2018 ◽  
Vol 10 (1) ◽  
pp. 26-53
Author(s):  
Junzhou Duan ◽  
Yubin Lu ◽  
Shu Zhang ◽  
Xiquan Jiang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Coarse Aggregate ◽  
Tensile Tests ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Dynamic Tensile Strength ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Direct Tensile

To comparatively study the tensile properties and fracture patterns of recycled aggregate concrete with various replacement percentages (i.e. 0%, 25%, 50%, 75%, and 100%) of recycled coarse aggregate, the dynamic direct tensile tests, splitting tests, and spalling tests of recycled aggregate concrete in the strain-rate range of 100–102 s−1 were carried out using large diameter (75 mm) split Hopkinson tensile bar and pressure bar. Test results show that for recycled aggregate concrete, the quasi-static direct tensile strength is more marvelous than its quasi-static splitting strength. When recycled coarse aggregate replacement percentage is 0%–75%, the replacement percentage impact minimally on the quasi-static tensile strength of recycled aggregate concrete. In dynamic tensile tests, there exists apparent difference between the dynamic direct tensile strength and dynamic splitting. The dynamic tensile strength of recycled aggregate concrete increases with the increase of average strain-rate in all three kinds of tests. The average strain-rate affects the damage form of recycled aggregate concrete, which indicates that the recycled aggregate concrete has obvious rate sensitivity. There shows no obvious regularity between the dynamic tensile strength and the recycled coarse aggregate replacement percentage. And the indirect tensile strength calculation method used in this article offers the theoretical basis for the engineering application of recycled aggregate concrete.

Study on Performance of Recycled Aggregate Concrete

2011 ◽  
Vol 477 ◽  
pp. 280-289 ◽  
Author(s):  
Shao Wei Yao ◽  
Zhen Guo Gao ◽  
Chang Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Physical And Mechanical Properties ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chemical Solution ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Natural Aggregate ◽  
Strength And Durability

The properties of recycled coarse aggregate and the slump, the physical and mechanical properties and durability of recycled aggregate concrete were studied through tests. The results indicate that the slump, compressive strength and durability of concrete with recycled aggregate are lower than that of concrete with natural aggregate when recycled coarse aggregate fully absorbs water. However, the slump can be similar to that of concrete with natural aggregate. The properties of recycled aggregate concrete can be improved by strengthening the recycled coarse aggregate, and it is also found that the recycled coarse aggregate strengthened by grinding is superior to that soaked by chemical solution.

Experimental Research on Mechanical Properties of Recycled Aggregate Concrete under Uniaxial Loading

2013 ◽  
Vol 671-674 ◽  
pp. 1736-1740
Author(s):  
Xue Yong Zhao ◽  
Mei Ling Duan
Keyword(s):  
Elastic Modulus ◽  
Coarse Aggregate ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Peak Strain ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate

The complete stress-strain curves of recycled aggregate concrete with different recycled coarse aggregate replacement percentages were tested and investigated. An analysis was made of the influence of varying recycled coarse aggregate contents on the complete stress-strain curve, peak stress, peak strain and elastic modulus etc. The elastic modulus of RC is lower than natural concrete (NC), and with the recycled coarse aggregate contents increase, it reduces. While with the increase of water-cement ratio (W/C), recycled concrete compressive strength and elastic modulus improve significantly. In addition, put forward a new equation on the relationship between Ec and fcu of the RC.

scholarly journals Properties of Concrete Using Treated Low-Class Recycled Coarse Aggregate and Blast Furnace Slag Sand

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 843
Author(s):  
Yuji Miyazaki ◽  
Takeshi Watanabe ◽  
Yuji Yamada ◽  
Chikanori Hashimoto
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Hardened Concrete ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Furnace Slag

Since high quality natural aggregates are becoming scarce, it is important that industrial recycled products and by-products are used as aggregates for concrete. In Japan, the use of recycled aggregate (RG) is encouraged. Since, strength and durability of recycled aggregate concrete is lower than that of normal aggregate concrete, the use of recycled aggregate has not been significant. In order to improve physical properties of concrete using recycled coarse aggregate, blast furnace slag sand has been proposed. Recently, blast furnace slag sand is expected to improve durability, freezing, and thawing damage of concrete in Japan. Properties of fresh and hardened concrete bleeding, compressive strength, and resistance to freezing and thawing which are caused by the rapid freezing and thawing test using liquid nitrogen is a high loader than the JIS A 1148 A method that were investigated. As a result, concrete using treated low-class recycled coarse aggregate and 50% or 30% replacement of crushed sand with blast furnace slag sand showed the best results, in terms of bleeding, resistance to freezing and thawing.

Experimental Research on Main Properties of New Recycled Coarse Aggregate Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 19-23 ◽  
Author(s):  
Da Xing Qian ◽  
Ying Wei Yun ◽  
Ii Young Jang ◽  
Jong Hoe Kim
Keyword(s):  
Concrete Beam ◽  
Coarse Aggregate ◽  
Economic Benefits ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Secondary Process ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Waste Concrete

Recently reutilization of waste concrete becomes one of the hottest issues in civil engineering field throughout the world. However, most of the concerned research focuses on the RCA (recycled coarse aggregate) by simply crushing waste concrete. In this paper shucking technique is developed to secondary process the simply crushing waste concrete for improving the performance of RCA concrete. Test has been done to demonstrate that performances such as strength, elastic modulus et al. of shucking RCA concrete is better than those of common recycled concrete. Simultaneously, beam specimens are made to test the flexural behavior of shucking RCA concrete. Results showed that the deflection of shucking RCA concrete beam is approximately same with that of natural coarse aggregate concrete beam, which solves current problem that recycled aggregate concrete beam has bigger deflection than common concrete beam. The new shucking technique developed in this paper has many advantages to be applied in practical engineering and it has obvious economic benefits and social effect.

EXPERIMENTAL INVESTIGATION ON SELF CURING RECYCLED AGGREGATE CONCRETE MEMBERS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
V. Bhikshma ◽  
J. Ravi Kumar
Keyword(s):  
Coarse Aggregate ◽  
Heat Of Hydration ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Curing Agent ◽  
Rc Beams ◽  
Aggregate Concrete ◽  
Peg 6000 ◽  
Recycled Coarse Aggregate

Self-curing concrete is an important aspect in strength development, which is neglected due to various reasons such as shortage of water, inaccessibility of structures during curing. Self-curing agents play important role in heat of hydration and strength development. The present study involves the use of self-curing agent polyethylene glycol (PEG 6000). In this investigation, M20 to M50 grade concrete has been considered to evaluate strength characteristics and flexural behavior using natural and recycled aggregate concrete. The various percentages of PEG 6000 have been used. The test result indicates self-curing concrete has indicated strength enhancement compared to conventional curing concrete. The strength for normal coarse aggregate concrete with a self-curing agent (PEG 6000) at 2% with 10% GGBS is decreased when compared with recycled coarse aggregate concrete with 1% (PEG 6000) with addition 10% GGBS. Mechanical properties are 7% to 20% higher for self-curing concrete when compared to natural concrete. Similarly, the flexural strength of normal coarse aggregate concrete was found to be varying from 4% to 16% more than with recycled coarse aggregate concrete at 28 days. Ultimate deflection of RC beams is 10% greater than the NC beams and ultimate moments of RC beams were 1% to 3% less than the corresponding NC beams. The moment-curvature relationship and load-deflection characteristics of the NC beams and RC beams show a similar trend.

Reliability Analysis on Load-Bearing Capacity of Axially Loaded of Recycled Aggregate Concrete-Filled Steel Tube

2014 ◽  
Vol 711 ◽  
pp. 438-443
Author(s):  
Rong Hua Yang ◽  
Gao Bo Mai
Keyword(s):  
Reliability Index ◽  
Coarse Aggregate ◽  
Great Influence ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Order Moment ◽  
Aggregate Concrete ◽  
Concrete Filled Steel Tube ◽  
Recycled Coarse Aggregate

The first degree second order moment method (JC method) is applied to analyze the reliability of recycled aggregate concrete-filled steel tube (RACFST). Several performances are studies, which are the influences of different load combinations, specific values of loads,confinement coefficients and recycled coarse aggregate replacement percentage on the reliability of the column. It is found that the reliability index varied with the load combination and specific value of loads. The analytical results indicate that the reliability index of the round steel tube is higher than square steel tube and the influence of recycled coarse aggregate replacement percentage can almost be ignored It can be concluded that the formula had great influence on reliability index and the revised formula can meet the requirements of the ductility of structure reliability.

scholarly journals Quality Improvement of Recycled Aggregate Concrete using Six Sigma DMAIC Methodology

2020 ◽  
Vol 5 (6) ◽  
pp. 1409-1419
Author(s):  
Suhas Vijay Patil ◽  
Balakrishna Rao K. ◽  
Gopinatha Nayak
Keyword(s):  
Six Sigma ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Lower Grade ◽  
Test Results ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Concrete Mix

Recycled aggregates (RA) are obtained from construction and demolished waste, laboratory crushed concrete and concrete waste at RMC plants. The concrete made from recycled aggregate is known as recycled aggregate concrete. The use of recycled aggregate is very beneficial to the environment in civil works. Its usage also helps in financial saving as the cost of transportation and production energy cost of natural coarse aggregate (NCA) is reduced. In India, the recycled aggregate application in lower grade concrete work is observed. However, the effect of recycled aggregate on the strength and durability of concrete restricts its use in higher-grade work. This paper presents a series of tests carried out on recycled coarse aggregate (RCA) and recycled coarse aggregate concrete (RCAC) and test results are compared with the NCA and parent concrete made from NCA. Tests were carried out as per IS code and concrete was prepared using a two-stage mixing approach in the concrete mix design. M30 concrete mix of four RCAC samples was tested at 28 days of curing and in comparison with parent concrete, it is found that on an average compressive strength is decreased by 12.89% at 28 days curing. Adhered mortar increases the porosity of the recycled aggregate and forms a weak zone between aggregate surface and mortar. In addition, test results showed the defects in recycled aggregate and helped to identify the area where concentration is necessary to improve the quality of recycled aggregate using six sigma DMAIC methodology. Total of 12 defects were found in the process and raw material. Statistical analysis was used to evaluate the performance of all the mix made with RCA.

Properties of the Recycled Aggregate Concrete

2012 ◽  
Vol 217-219 ◽  
pp. 866-868
Author(s):  
Wei Ren
Keyword(s):  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Performance Impact ◽  
Construction Waste ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Concrete Blocks

This paper studies the construction waste recycled coarse aggregate concrete blocks including waste and brick, through the control of brick in the admixture of recycled coarse aggregate concrete, compound to regenerate waste away in the analysis and research of the brick dosage of recycled concrete performance impact.

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