Effects of parent concrete and mixing method on the resistance to freezing and thawing of air-entrained recycled aggregate concrete

2016 ◽  
Vol 106 ◽  
pp. 264-273 ◽  
Author(s):  
Kaihua Liu ◽  
Jiachuan Yan ◽  
Qiong Hu ◽  
Yao Sun ◽  
Chaoying Zou
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Mixing Method

Quality Improvement of Recycled Aggregate Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 308-313 ◽  
Author(s):  
Vivian W.Y. Tam ◽  
X.F. Gao ◽  
C.M. Tam
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Two Stage ◽  
New Approach ◽  
Aggregate Concrete ◽  
Strength Based ◽  
Mixing Method ◽  
Strength Variability

The developments of recycled aggregate concrete pressing hard in construction activities; however, the limitations on their applications had never being ended. The focus of this paper is: i) investigating the waste management strategy in construction; ii) proposing the two-stage mixing approach (TSMA) to improve the quality of RAC; and iii) experimenting the TSMA and assessing the benefits possibly gained. It proposes a new approach in mixing concrete, namely, the two-stage mixing method, to improve compressive strength of RAC and lower its strength variability. The replacement ratio from zero to thirty is under experiment on their compressive strength. Based upon the experimental results, improvements of 31 % in strength at 28 days with 30 % RA substitute was achieved. The effect can be attributably to the porous nature of the RA and the pre-mix process which can make some pores filled up resulting in a denser concrete and thus leading to higher strength when compared with the traditional mixing approach. Therefore, two-stage mixing approach can open up a wider application of recycled aggregate concrete.

scholarly journals A Study on the Properties of Recycled Aggregate Concrete and Its Production Facilities

2019 ◽  
Vol 9 (9) ◽  
pp. 1935 ◽  
Author(s):  
Jung-Ho Kim ◽  
Jong-Hyun Sung ◽  
Chan-Soo Jeon ◽  
Sae-Hyun Lee ◽  
Han-Soo Kim
Keyword(s):  
Drying Shrinkage ◽  
Quality Standards ◽  
Poor Quality ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Freezing And Thawing ◽  
Construction Waste ◽  
Aggregate Concrete ◽  
Air Volume

In recent years, the amount of construction waste and recycled aggregate has been increasing every year in Korea. However, as the recycled aggregate is poor quality, it is not used for concrete, and the Korean government has strengthened the quality standards for recycled aggregate for concrete. In this study, research was conducted on the mechanical and durability characteristics of concrete using recycled aggregate, after developing equipment to improve the quality of recycled aggregate to increase the use of recycled aggregate for environmental improvements. The results illustrated improvements in the air volume, slump, compressive strength, freezing and thawing resistance, and drying shrinkage. Furthermore, this study is expected to contribute to the increased use of recycled aggregate in the future.

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.

Relationship between Microstructure and Mechanical Properties for Recycled Aggregate Concrete

2013 ◽  
Vol 811 ◽  
pp. 213-217
Author(s):  
Wei Li ◽  
Wen Sheng Ding ◽  
Hai Ying Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Average Pore ◽  
Aggregate Concrete ◽  
Active Particles ◽  
Lower Porosity ◽  
Porous Microstructure ◽  
Mixing Method

Microstructure is an important factor that influences the mechanical properties of recycled aggregate concrete (RAC). This paper was devoted to an investigation of the relationship between mechanical properties and porosity, hydrate, microstructure of interfacial transition zone (ITZ) in RAC. The result showed that mechanical properties of RAC can be further enhanced with lower porosity, and there was a good linear relation, whereas it did not exist between compressive strength of RAC and average pore diameter. Fine active particles and the hydrate were formed into the cracked and loose layer of ITZ in RAC by A tripe mixing method (TM). Through SEM observation, it is expected that the compressive strength of the RAC can be improved by modifying the porous microstructure and hydrate in ITZ.

An Experimental Study on the Chloride Penetration Resistance of Recycled Aggregate Concrete

2011 ◽  
Vol 71-78 ◽  
pp. 1255-1258
Author(s):  
Jian Jiang Ding ◽  
Jian Jun Zheng ◽  
Ting Lei ◽  
De Yu Kong
Keyword(s):  
Significant Influence ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete ◽  
Mixing Method ◽  
Chloride Penetration Resistance ◽  
Theoretical Evidence

The degradation of reinforced concrete structures due to chloride penetration has a significant influence on structural durability. In this study, an experiment is conducted to investigate the effects of the aggregate type, mixing method, and admixture type on the chloride penetration resistance of concrete. Based on the experimental results, it is found that, since more pores and microcracks are included in recycled aggregates, the chloride penetration resistance of recycled aggregate concrete is larger than that of natural aggregate concrete. Slag is more efficient than fly ash in increasing the chloride penetration resistance of recycled aggregate concrete. It is also found that the mixing method has a significant influence on the chloride penetration resistance of recycled aggregate concrete. These conclusions can provide theoretical evidence for the design optimization of recycled aggregate concrete properties.

Experiment on Freezing and Thawing Durability Characteristics of Recycled Aggregate Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 447-452 ◽  
Author(s):  
Hong Bing Zhu ◽  
Xiu Li
Keyword(s):  
Compressive Strength ◽  
Weight Change ◽  
Strength Test ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Rapid Freezing ◽  
Freezing And Thawing ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Compressive Strength Test

Recycling old concrete as an alternative source for production new concrete can solve the environment produced by old concrete. To make such recycling feasible, the strength and durability of the recycled aggregate concrete (RAC) must be assured. Prepared recycled coarse and fine aggregate using natural concrete specimens produced by compressive strength test of cubic concrete. Prepared recycled aggregate concrete which replacement ratios is 50% and 70%. Processed compressive strength test of cubic RAC specimens. Carried through the test for resistance of concrete to rapid freezing and thawing on both RAC and natural concrete. As a result of the experiment, the strength of the RAC can reach the design strength, however, the index for the resistance of concrete to rapid freezing and thawing depressed to a certainty degree relative to that of common concrete. Replacement ratio of aggregate influenced relative dynamic modulus of elasticity of RAC seriously. The weight change increased as long as the number of freezing and thawing cycles increased, and the weight change increased when replacement ratio elevation. RAC showed a sharp weight loss during the testing period, and reduce the water cement ratio can increase the durability characteristics of RAC. Also, absorption of the recycled aggregate influenced durability properties of RAC badly.

A Review of the Durability of Recycle Aggregate Concrete

2015 ◽  
Vol 744-746 ◽  
pp. 1357-1360 ◽  
Author(s):  
Hong Bo Liu ◽  
Jing Sun ◽  
Xiao Hong Cong
Keyword(s):  
Drying Shrinkage ◽  
Present Situation ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycle Aggregate ◽  
Freezing And Thawing ◽  
Chloride Permeability ◽  
Technical Problems ◽  
Aggregate Concrete ◽  
Related Literature

Analyzing the related literature at home and abroad, this paper summarized the results and shared them with reasearchers involved in the field on the recycled aggregate concrete (RAC). In this paper, the durability of RAC will be described from the following several aspects: absorption, chloride permeability, freezing and thawing resistance, carbonation, the sulfate corrosion resistance, drying shrinkage, creep and abrasion resistance. This paper expounded the present situation and progress in the study of the durability of recycled aggregate concrete.Then, some key technical problems needed to be studied were pointed out and many suggestions were put forward.

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