scholarly journals Durability of concrete containing aggregate produced from recycled concrete affected by alkali-silica reaction

2021 ◽  
Author(s):  
Chris Christidis
Keyword(s):  
Coarse Aggregate ◽  
High Reactivity ◽  
Recycled Concrete ◽  
Alkali Silica Reaction ◽  
Concrete Aggregate ◽  
Freezing And Thawing ◽  
Salt Scaling ◽  
And Control ◽  
Minimal Information ◽  
Durability Of Concrete

Minimal information is available on the durability of concrete containing demolished concrete as an aggregate. The purpose of this study was to: investigate and control the reactivity of recycled concrete aggregate (RCA) produced from concrete that was suffering from alkali silica reaction (ASR); and investigate other durability issues of concrete containing RCA with emphasis on salt scaling and freezing & thawing. It was deduced that the RCA produced from ASR-affected concrete caused expansion when used in new concrete as an aggregate. This high reactivity of the tested RCA was attributable to its relatively high alkalis and calcium contents. Furthermore, a greater amount of SCM was required to reduce expansion compared to concrete containing raw natural reactive aggregate. In terms of freezing and thawing and salt scaling, concrete containing coarse RCA at a 100% replacement level of coarse aggregate showed lower durability compared to concrete made with natural coarse aggregate.

scholarly journals Durability of concrete containing aggregate produced from recycled concrete affected by alkali-silica reaction

2021 ◽  
Author(s):  
Chris Christidis
Keyword(s):  
Coarse Aggregate ◽  
High Reactivity ◽  
Recycled Concrete ◽  
Alkali Silica Reaction ◽  
Concrete Aggregate ◽  
Freezing And Thawing ◽  
Salt Scaling ◽  
And Control ◽  
Minimal Information ◽  
Durability Of Concrete

Minimal information is available on the durability of concrete containing demolished concrete as an aggregate. The purpose of this study was to: investigate and control the reactivity of recycled concrete aggregate (RCA) produced from concrete that was suffering from alkali silica reaction (ASR); and investigate other durability issues of concrete containing RCA with emphasis on salt scaling and freezing & thawing. It was deduced that the RCA produced from ASR-affected concrete caused expansion when used in new concrete as an aggregate. This high reactivity of the tested RCA was attributable to its relatively high alkalis and calcium contents. Furthermore, a greater amount of SCM was required to reduce expansion compared to concrete containing raw natural reactive aggregate. In terms of freezing and thawing and salt scaling, concrete containing coarse RCA at a 100% replacement level of coarse aggregate showed lower durability compared to concrete made with natural coarse aggregate.

scholarly journals Properties of concrete containing recycled concrete aggregate of preserved quality

2021 ◽  
Author(s):  
Jonathan Andal
Keyword(s):  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Salt Scaling ◽  
Concrete Properties ◽  
Comparable Quality ◽  
Scaling Resistance

Today, there is a growing need for the implementation of sustainability in construction. Continuous construction and rehabilitation projects have begun to deplete virgin aggregate sources. The use of recycled concrete aggregate (RCA) in concrete has been regarded as a sustainable and environmentally friendly alternative aggregate source. This thesis focuses on producing RCA of preserved quality through the use of a new protocol aimed at maintaining the original properties of returned-to-plant concrete. The performance of RCA with preserved quality and commercially available RCA when used in concrete was compared. Different concrete properties were evaluated including the fresh, hardened and durability characteristics. Results showed that the RCA with preserved quality performed better in many categories, including strength, drying shrinkage and salt scaling resistance compared to the commercial RCA. The use of 30% preserved-quality RCA as partial replacement of coarse aggregate produced concrete of comparable quality to that produced with virgin aggregate.

scholarly journals Untitled ItemProperties of Concrete Containing Recycled Concrete Aggregate of Preserved Quality

2021 ◽  
Author(s):  
Medhat Shehata ◽  
Jonathan Andal ◽  
Philip Zacarias
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
High Quality ◽  
Salt Scaling ◽  
Comparable Quality ◽  
Scaling Resistance

<p>This study focuses on evaluating recycled concrete aggregate (RCA) of high quality produced through a protocol that preserves the original properties of the concrete to be recycled. Concrete with RCA of preserved quality was compared to concrete with commercially available RCA. A total of 29 mixes were tested with RCA replacement ranging from 30% to 100% of the coarse aggregate. Results showed that concrete with RCA of preserved quality performed significantly better in compressive strength, drying shrinkage, and salt scaling resistance. Furthermore, the use of 30% RCA with preserved quality produced concrete of comparable quality to that of concrete with natural aggregate.</p>

scholarly journals Properties of Concrete Containing Recycled Concrete Aggregate of Preserved Quality

2021 ◽  
Author(s):  
Medhat Shehata ◽  
Jonathan Andal ◽  
Philip Zacarias
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
High Quality ◽  
Salt Scaling ◽  
Comparable Quality ◽  
Scaling Resistance

<p>This study focuses on evaluating recycled concrete aggregate (RCA) of high quality produced through a protocol that preserves the original properties of the concrete to be recycled. Concrete with RCA of preserved quality was compared to concrete with commercially available RCA. A total of 29 mixes were tested with RCA replacement ranging from 30% to 100% of the coarse aggregate. Results showed that concrete with RCA of preserved quality performed significantly better in compressive strength, drying shrinkage, and salt scaling resistance. Furthermore, the use of 30% RCA with preserved quality produced concrete of comparable quality to that of concrete with natural aggregate.</p>

scholarly journals Properties of concrete containing recycled concrete aggregate of preserved quality

2021 ◽  
Author(s):  
Jonathan Andal
Keyword(s):  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Salt Scaling ◽  
Concrete Properties ◽  
Comparable Quality ◽  
Scaling Resistance

Today, there is a growing need for the implementation of sustainability in construction. Continuous construction and rehabilitation projects have begun to deplete virgin aggregate sources. The use of recycled concrete aggregate (RCA) in concrete has been regarded as a sustainable and environmentally friendly alternative aggregate source. This thesis focuses on producing RCA of preserved quality through the use of a new protocol aimed at maintaining the original properties of returned-to-plant concrete. The performance of RCA with preserved quality and commercially available RCA when used in concrete was compared. Different concrete properties were evaluated including the fresh, hardened and durability characteristics. Results showed that the RCA with preserved quality performed better in many categories, including strength, drying shrinkage and salt scaling resistance compared to the commercial RCA. The use of 30% preserved-quality RCA as partial replacement of coarse aggregate produced concrete of comparable quality to that produced with virgin aggregate.

scholarly journals Properties of Concrete Containing Recycled Concrete Aggregate of Preserved Quality

2021 ◽  
Author(s):  
Medhat Shehata ◽  
Jonathan Andal ◽  
Philip Zacarias
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
High Quality ◽  
Salt Scaling ◽  
Comparable Quality ◽  
Scaling Resistance

<p>This study focuses on evaluating recycled concrete aggregate (RCA) of high quality produced through a protocol that preserves the original properties of the concrete to be recycled. Concrete with RCA of preserved quality was compared to concrete with commercially available RCA. A total of 29 mixes were tested with RCA replacement ranging from 30% to 100% of the coarse aggregate. Results showed that concrete with RCA of preserved quality performed significantly better in compressive strength, drying shrinkage, and salt scaling resistance. Furthermore, the use of 30% RCA with preserved quality produced concrete of comparable quality to that of concrete with natural aggregate.</p>

scholarly journals Recycled Concrete Aggregate for Medium-Quality Structural Concrete

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4612
Author(s):  
Dong Viet Phuong Tran ◽  
Abbas Allawi ◽  
Amjad Albayati ◽  
Thi Nguyen Cao ◽  
Ayman El-Zohairy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Predictive Equation ◽  
Recycled Concrete Aggregate ◽  
Structural Concrete ◽  
Medium Quality ◽  
Ultrasound Pulse

This paper reports an evaluation of the properties of medium-quality concrete incorporating recycled coarse aggregate (RCA). Concrete specimens were prepared with various percentages of the RCA (25%, 50%, 75%, and 100%). The workability, mechanical properties, and durability in terms of abrasion of cured concrete were examined at different ages. The results reveal insignificant differences between the recycled concrete (RC) and reference concrete in terms of the mechanical and durability-related measurements. Meanwhile, the workability of the RC reduced vastly since the replacement of the RCA reached 75% and 100%. The ultrasound pulse velocity (UPV) results greatly depend on the porosity of concrete and the RC exhibited higher porosity than that of the reference concrete, particularly at the transition zone between the RCA and the new paste. Therefore, the sound transmission in the RC required longer times than that in the reference concrete. Moreover, a predictive equation relating the compressive strength to the UPV was developed.

scholarly journals Effect of River Indus Sand and Recycled Concrete Aggregates as Fine and Coarse Replacement on Properties of Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3832-3835 ◽  
Author(s):  
A. R. Sandhu ◽  
M. T. Lakhiar ◽  
A. A. Jhatial ◽  
H. Karira ◽  
Q. B. Jamali
Keyword(s):  
Tensile Strength ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Compressive Strength Of Concrete ◽  
River Indus ◽  
Concrete Materials

As the demand for concrete rises, the concrete materials demand increases. Aggregates occupy 75% of concrete. A vast amount of aggregates is utilized in concrete while aggregate natural resources are reducing. To overcome this problem, River Indus sand (RIS) and recycled concrete aggregate (RCA) were utilized as fine and coarse aggregate respectively. The aim of this experimental investigation is to evaluate the workability, and compressive and tensile strength of concrete utilizing RIS and RCA. Concrete samples of 1:2:4 proportions were cast, water cured for 7, 14, 21 and 28 days, and tested for compressive and tensile strength. The outcomes demonstrate that concrete possessed less workability when RIS and RCA were utilized. It was predicted that compressive strength of concrete would reduce up to 1.5% when 50% RIS and 50% RCA were utilized in concrete and 11.5% when natural aggregate was fully replaced by RIS and RCA, whereas the tensile strength decreased up to 1.60% when 50% by 12% respectively.

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