Mechanical Properties of Recycled Aggregate Concrete Under Uniaxial Loading

Recycled aggregate from C&D waste & its use in concrete – A breakthrough towards sustainability in construction sector: A review

An overview of study on recycled aggregate concrete in China (1996-2011)

Properties and composition of recycled aggregates from construction and demolition waste suitable for concrete production

Construction and Demolition (C&D) waste constitutes a major portion of total solid waste production in the world, and most of it is used in land fills. Research by concrete engineers has clearly suggested the possibility of appropriately treating and reusing such waste as aggregate in new concrete, especially in lower level applications. This paper discusses different aspects of the problem beginning with a brief review of the international scenario in terms of C&D waste generated, recycled aggregates (RA) produced from C&D waste and their utilization in concrete and governmental initiatives towards recycling of C&D waste. Along with a brief overview of the engineering properties of recycled aggregates, the paper also gives a summary of the effect of use of recycled aggregate on the properties of fresh and hardened concrete. The paper concludes by identifying some of the major barriers in more widespread use of RA in recycled aggregate concrete (RAC), including lack of awareness, lack of government support, non-existence of specifications/codes for reusing these aggregates in new concrete.

Use of aggregates from recycled construction and demolition waste in concrete

This study is conducted (1) to examine the influence of recycled aggregate on interfacial transition zone (ITZ), strength, chloride penetration, and carbonation of concrete, and (2) to propose a method for improving strength, chloride penetration, and carbonation resistances of concrete using recycled aggregates Five types of recycled aggregate, and four levels of water-binder ratio are used in this study The recycled aggregate concrete is evaluated according to compressive strength, tensile strength, chloride penetration depth, and carbonation depth The characteristics of ITZs in recycled aggregate concrete are also measured and used to explain the influence of recycled aggregate on the mentioned properties Additionally, the double-mixing method for improving strength, chloride penetration, and carbonation resistances of recycled aggregate concrete is evaluated in this study

Influence of Recycled Aggregate on Interfacial Transition Zone, Strength, Chloride Penetration and Carbonation of Concrete

This study experimentally investigated the influences of bending crack and water-cement ratio (w/c) on the chloride-induced corrosion on main reinforcing bars and stirrups. Special features of this study included crack formation through application of bending load, consideration of main reinforcing bars and stirrups together, and measurements of both macrocell and microcell currents. An indoor examination investigated the corrosion of main reinforcing bars and stirrups on model beams. To clarify the indoor examination results, larger-scale beams exposed to an outdoor environment were investigated. Results showing the influences of bending cracks and w/c on the corrosion rate were reported.

Influences of Bending Crack and Water-Cement Ratio on Chloride-Induced Corrosion of Main Reinforcing Bars and Stirrups

Steel in concrete may corrode due to chloride or carbonation especially at cracks and joints. The objective of this study is to experimentally investigate comprehensively the pattern of corrosion cell formation (macrocell and microcell) as well as the corrosion rate using mortar specimens with defects simulating cracks and/or joints. The three important factors are listed as follows: 1) supply position of chloride ions or carbon dioxide, 2) environmental conditions, and 3) water-cement ratio of mortar. The results indicate that, in the case of chloride induced corrosion, decreasing the water-cement ratio (0.3) increased the activity of macrocell prominent corrosion. On the other hand, increasing the water-cement ratio (0.7) increased the activity of microcell prominent corrosion. Therefore, in the presence of defects, a high corrosion rate might be promoted even at a low water-cement ratio. The study also reveals that, in the case of carbonation induced corrosion, macrocell prominent corrosion occurred regardless of the water-cement ratio, and the lower the water-cement ratio, the lower the corrosion rate. Finally, the study proves that the corrosion rate induced by chloride was higher than that induced by carbonation.

Steel Corrosion Induced by Chloride or Carbonation in Mortar with Bending Cracks or Joints

Durability against Steel Corrosion of HPFRCC with Bending Cracks

本研究では, 塩害により劣化した鉄筋コンクリート構造物を断面修復工法により補修した後に発生する, 内部鉄筋のマクロセル腐食に関して, 実験的検討を行った. その結果, (1) 塩化物イオン含有量, 水セメント比および材料が, 打継目を貫く鉄筋のマクロセル発生機構に及ぼす影響, (2) 外部環境の湿度や温度がマクロセル腐食速度に及ぼす影響について評価することが出来た.

Shinichi Miyazato

Papers

Influence of Recycled Aggregate on Interfacial Transition Zone, Strength, Chloride Penetration and Carbonation of Concrete

Influences of Bending Crack and Water-Cement Ratio on Chloride-Induced Corrosion of Main Reinforcing Bars and Stirrups

Steel Corrosion Induced by Chloride or Carbonation in Mortar with Bending Cracks or Joints

Durability against Steel Corrosion of HPFRCC with Bending Cracks

The experimental study on corrosion mechanism of reinforced concrete at local repair part