scholarly journals The Simple Mix Design Method and Confined Behavior Analysis for Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3533
Author(s):  
Chong Rong ◽  
Jing Ma ◽  
Qingxuan Shi ◽  
Qiuwei Wang
Keyword(s):  
Design Method ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Confined Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Aggregate Concrete ◽  
Confining Effect ◽  
Study Results ◽  
The Common

For the environment protection and sustainable development in building construction, waste concrete can be processed into recycled aggregate to mix the recycled aggregate concrete (RAC). However, the existing mix design methods of RAC were complex, and the mechanical properties of RAC were more weakened than ordinary concrete. This paper presents a simple mix design method for RAC, including orthogonal test and single-factor test. Then, in order to study the behavior of confined RAC, this paper presents a comprehensive experimental study on the RAC filled in steel tube (RCFST) specimens and the RAC filled in GFRP tube (RCFST) specimens. The results show that the proposed mix design method can mix different stable strength grades of RAC promptly and efficiently. In addition, the steel tube and GFRP tube can provide a well confining effect on core RAC to improve the mechanical behavior of column. Moreover, the properties of core RAC in steel tube are the same as the common passive confined concrete, and the properties of core RAC in the GFRP tube are the same as the common active confined concrete. The study results can provide reference for other kinds of RAC mixtures as well as be a foundation for theoretical studies on confined RAC.

A Study on the GA-Based Design for Recycled Aggregate Concrete

2013 ◽  
Vol 284-287 ◽  
pp. 1225-1229
Author(s):  
Won Jun Park
Keyword(s):  
Design Method ◽  
Optimization Technique ◽  
Evolutionary Process ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Aggregate Concrete ◽  
Fitness Functions ◽  
Mix Proportion ◽  
Object Problem

Various desired performances of concrete, i.e. strength, slump, durability, etc., cannot be always obtained by current conventional mix proportion design methods for recycled aggregate concrete (RAC), because recycled aggregate (RA) generally has lower quality than natural aggregate due to the residual cement paste attached on RA and various impurities. On the other hand, design of concrete mix proportion using RA can be solved as the multi-criteria problem to meet the various required performances. This paper suggests a new method for the mix proportion of RAC to reduce the number of trial mixes using genetic algorithm (GA) which has been an optimization technique to solve the multi-object problem throughout the simulated biological evolutionary process. In mix design method by GA, several fitness functions for the required properties of concrete, i.e., slump, strength, carbonation speed coefficient, price, and emission of CO2 were considered based on conventional data or adapted from various early studies. As a result, various optimum mix proportions for RAC that meet required performances were obtained according to assumed case studies.

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