Methodology for the integrated assessment on the use of recycled concrete aggregate replacing natural aggregate in structural concrete

2017 ◽  
Vol 166 ◽  
pp. 321-334 ◽  
Author(s):  
Mayuri Wijayasundara ◽  
Priyan Mendis ◽  
Robert H. Crawford
Keyword(s):  
Integrated Assessment ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Structural Concrete ◽  
Natural Aggregate

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 Effects of pre-wetting aggregate on the properties of mortars made with recycled concrete and lightweight aggregates

2019 ◽  
Vol 24 (2) ◽  
Author(s):  
Lidiane Fernanda Jochem ◽  
Diego Aponte ◽  
Marilda Barra Bizinotto ◽  
Janaíde Cavalcante Rocha
Keyword(s):  
Lightweight Aggregate ◽  
Heat Of Hydration ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Dry Density ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Natural Aggregate ◽  
Entrained Air ◽  
Dimensional Instability

ABSTRACT This paper examines the suitability of partially replacing natural aggregate, sand, (NA) with recycled concrete aggregate (RCA) or lightweight aggregate (LWA) in mortars, under the hypothesis that pre-wetting aggregates would produce improvement in mortar properties. Fresh mortar properties such as density, entrained air content, consistency and heat of hydration, as well as hardened mortar properties such as dry density, compressive and flexural strength, and dimensional instability at 0% and 100% saturation were determined. The results show that mortars made with natural aggregate (75%) and recycled concrete aggregate (25%) have similar properties to mortars made with only natural aggregate (100%) and that pre-wetting the aggregates does not influence the properties of mortars significantly. Therefore, partial replacement with recycled concrete aggregate is a viable alternative for producing mortar.

scholarly journals Influence of Partial Coarse Fraction Substitution of Natural Aggregate by Recycled Concrete Aggregate in Hot Asphalt Mixtures

2019 ◽  
Vol 12 (1) ◽  
pp. 250 ◽  
Author(s):  
Debora Acosta Álvarez ◽  
Anadelys Alonso Aenlle ◽  
Antonio José Tenza-Abril ◽  
Salvador Ivorra
Keyword(s):  
Asphalt Concrete ◽  
Coarse Fraction ◽  
Asphalt Mixtures ◽  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Demolition Waste ◽  
Natural Aggregate

The main objective of this work is to evaluate the properties of hot asphalt mixtures that have been manufactured with different recycled concrete aggregate (RCA) percentages (0%, 20%, 40%, 60% and 80% of the fraction 5–13 mm) and asphalt (4%, 4.5% and 5%). Dense asphalt mixtures were made; partially replacing the natural aggregate (NA) fraction between 5 and 13 mm. Marshall specimens were manufactured to determine the main properties of the asphalt concrete (AC) in terms of density, voids, stability and deformation. Additionally, the optimal asphalt content (OAC) was determined, and measured the water sensibility, the stiffness modulus and the permanent deformation. The results corroborate the potential for using these sources of construction and demolition waste (CDW) as a RCA in asphalt concrete and show that the hot asphalt mixtures with up to 40% substitution of natural aggregate by recycled aggregate in the fraction 5–13 mm present good behavior.

scholarly journals Evaluation of the Feasibility of Recycled Concrete Aggregate for Producing Structural Concrete

2020 ◽  
Vol 220 ◽  
pp. 01098
Author(s):  
Mohammad Tabrez Ali ◽  
Ibadur Rahman ◽  
Nirendra Dev ◽  
Priyanka Singh
Keyword(s):  
Compressive Strength ◽  
Construction Materials ◽  
Recycled Concrete ◽  
Environmental Benefits ◽  
Mix Design ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Structural Concrete ◽  
Average Value ◽  
Maximum Compressive Strength

When sustainability has become a primary measure of the selection of the building materials in the construction industry over the past decades, researchers all around the world have been looking upon for alternatives to reduce the overall environmental impact of the construction materials while not compromising the strength and durability. The factors like manufacturing, reusability, recyclability, disposal etc, are the criteria of utmost attention affecting the overall life cycle impact of the construction materials. In this prospect the Recycled Concrete Aggregate (RCA) has shown up as an exceptionally viable contender for the manufacturing of concrete with several environmental benefits over the Natural Aggregate (NA) and has already been identified by industry and several government agencies across the globe. The efficient material use of RCA can potentially deliver an inferior though competent concrete in comparison to the NA while averring the criteria of sustenance. The present study delves into the calculation of the proportion of the RCA in a mix design for achieving maximum compressive strength. The experimental setup constituted the casting of concrete cubes of control mix design of M40 grade with proportions of RCA varying from 0-100 percent spread over a space of 10% with NA which were later put to tests. The thorough investigation on the casted concrete cubes lead to the conclusion that the mix design with 50% proportion of RCA in addition to 50% proportion of NA delivered the maximum compressive strength, an average value of 8.23% higher than that of the normal concrete and the highest Rebound Number, an average value of 53.92 for the M40 grade concrete thereby showcasing the feasibility of producing structural concrete with RCA. The results are asserted to be governed by the better bonding between the RCA and NA and due to the significant increase in the water retention capacity by the provision of RCA in the mix.

scholarly journals Asphalt Mixes Processed with Recycled Concrete Aggregate (RCA) as Partial Replacement of the Natural Aggregate

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4196
Author(s):  
Carlos U. Espino-Gonzalez ◽  
Wilfrido Martinez-Molina ◽  
Elia M. Alonso-Guzman ◽  
Hugo L. Chavez-Garcia ◽  
Mauricio Arreola-Sanchez ◽  
...  
Keyword(s):  
Research Work ◽  
Construction Materials ◽  
Recycled Concrete ◽  
International Standards ◽  
Partial Substitution ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Asphalt Mixes ◽  
Natural Aggregate

Materials play a fundamental role in any branch of civil engineering. From ancient times to the present day, society has required enormous amounts of construction materials, which implies an excessive exploitation of the natural environment. The present research work consisted in the design and development of asphalt mixes with a partial substitution of the natural aggregate (NA) by means of recycled concrete aggregate (RCA). The mix was designed with the Marshall methodology, considering the next percentages of substitution and addition by mass: 90% NA and 10% RCA; 80% NA and 20% RCA; 70% NA and 30% RCA. The mixtures were elaborated and analysed under the international standards and the Mexican regulation of the Communications and Transport Ministry, to determine the best option regarding their performance. The materials were characterized according to the current regulations and later employed in the mixes design. A total of 38 specimens were elaborated for each mixture, determining the optimum asphalt content; after that, mechanical tests were performed to analyse and determine the best results. In the aftermath of the examination of all mixtures, we concluded that the 70%AN/30%RCA is the best alternative option according to its performance and numeric results, complying with the cited regulations, and allowing a lower content of asphalt during the process.

scholarly journals Influence of acid treatment and carbonation on the properties of recycled concrete aggregate

2018 ◽  
Vol 24 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Aleksandar Radevic ◽  
Iva Despotovic ◽  
Dimitrije Zakic ◽  
Marko Oreskovic ◽  
Dragica Jevtic
Keyword(s):  
Quality Improvement ◽  
Water Absorption ◽  
Acid Treatment ◽  
Cement Mortar ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Accelerated Carbonation ◽  
Natural Aggregate ◽  
Reduced Water

Recycled concrete aggregate (RCA), obtained by crushing of original (old) concrete, consists of natural aggregate grains and a cement mortar matrix. The presence of old adhered cement mortar, which has higher porosity than natural aggregate, causes unfavourable properties of RCA. The research conducted in order to improve the quality of RCA and to enable its greater application in the construction industry is presented in this paper. Therefore, RCA was subjected to quality improvement treatments with hydrochloric acid and carbon dioxide (accelerated carbonation). The first procedure was aimed at partially removing the adhered cement mortar and the second at reinforcing the cement matrix. The physical, mechanical and chemical properties of all three types of RCA were tested. After the pre-soaking acid treatment (0.1 mol/dm3 HCl), RCA showed reduced water absorption (up to 3%); the process of accelerated carbonation also led to reduced water absorption (13?20%) as well as to improved mechanical properties (?10%). A scanning electron microscopy investigation revealed that the carbonation process, as expected, significantly reduces porosity of RCA. The overall results show that if RCA is obtained by crushing of compact, high- -quality concrete, the procedures of aggregate quality improvement are not necessary.

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