Properties of Concrete with Partial Replacement of Natural Aggregate by Recycled Concrete Aggregates from Precast Production

The influence of synchronous use of coarse and fine recycled concrete aggregates on durable performance of recycled aggregate concrete (RAC) in air environment were determined. In this study, three series of concrete mixtures were prepared, in which the coarse recycled aggregate was used as 0%, 30%, 60% and 90% replacements of coarse natural aggregate and fine recycled aggregate as 0%, 10%, 20%, and 30% replacements of fine natural aggregate. Meanwhile, fly ash and slag were used as 15%, 25%, 35% and 45% replacements of cement, respectively. The carbonation depths, compressive cube strength, workability of RACs were tested. The experimental results showed that RAC with synchronous use of coarse and fine recycled concrete aggregates had satisfactory durable performance. When RAC was used as structural concrete in air environment, the optimum synchronous replacements are 60% for coarse recycled aggregate and 20% for fine recycled aggregate.

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Design Strategy for Recycled Aggregate Concrete: A Review of Status and Future Perspectives

Crystals ◽

10.3390/cryst11060695 ◽

2021 ◽

Vol 11 (6) ◽

pp. 695

Author(s):

Natt Makul ◽

Roman Fediuk ◽

Mugahed Amran ◽

Abdullah M. Zeyad ◽

Sergey Klyuev ◽

...

Keyword(s):

Environmental Impact ◽

Natural Resources ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Construction And Demolition Waste ◽

Demolition Waste ◽

Construction Waste ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Natural Aggregate

Currently, a number of disadvantages hampers the use of recycled concrete aggregates (RCA). The current review proves that concretes made with complete replacement of natural aggregate with RCA allow the production of high-quality concrete. One of the possibilities for improving concrete properties with RCA is the use of extended curing and pozzolanic materials with varying cement ratios. The potential use of RCA concretes is in the production of high-value materials that increase environmental and financial benefits. RCA have strong potential in the development of a new generation of concrete and stimulate economic activity in many countries in addition to optimizing natural resources. Economic benefits include minimal travel costs; cheaper sources of concrete than newly mined aggregates; reduction of the landfill area required for the placement of concrete waste; the use of RCA minimizes the need for gravel extraction, etc. The proposed strategy could be to sequentially separate demolition waste such as roof finishes, waterproof materials, interior and exterior materials, etc. Closing life cycles is the main approach used for efficient structures for the recycling and reuse of construction and demolition waste in the production and recovery of materials, especially when recycling and reusing materials. In the life cycle, the recycling of recovered materials allows them to be used for new construction purposes, avoiding the use of natural concrete aggregates. Government, design institutes, construction departments and project managers should be involved in the creation and use of RCA. In demolition and construction, the main players are the project owners. Their obligations, expectations and responsibilities must be properly aligned. For the past 20 years, recycled concrete aggregate from demolition and construction waste has been considered as an alternative to pure concrete in structural concrete to minimize the environmental impact of construction waste and demolition waste and the conversion of natural aggregate resources. It is now recognized that the use of RCA for the generations of concrete is a promising and very attractive technology for reducing the environmental impact of the construction sector and conserving natural resources. In the market, the selling price is not an obstacle for market applications of RCA, as there are scenarios in which their cost is lower than the cost of products made from conventional building materials. This is more of an acceptance factor in the market for recycled concrete aggregates. In this sector, the lack of identification, accreditation and uniform quality certification systems and their narrow application cause some marketing problems. With proper RCA preparation, concrete with standard physical and mechanical properties and performance characteristics can be obtained.

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Characterization of pervious concrete with blended natural aggregate and recycled concrete aggregates

Journal of Cleaner Production ◽

10.1016/j.jclepro.2018.01.205 ◽

2018 ◽

Vol 181 ◽

pp. 155-165 ◽

Cited By ~ 37

Author(s):

Soon Poh Yap ◽

Paul Zhao Chiat Chen ◽

Yingxin Goh ◽

Hussein Adebayo Ibrahim ◽

Kim Hung Mo ◽

...

Keyword(s):

Recycled Concrete ◽

Pervious Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Natural Aggregate

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Rheology of Alkali-Activated Mortars: Influence of Particle Size and Nature of Aggregates

Minerals ◽

10.3390/min10080726 ◽

2020 ◽

Vol 10 (8) ◽

pp. 726

Author(s):

Sara Gismera ◽

María del Mar Alonso ◽

Marta Palacios ◽

Francisca Puertas

Keyword(s):

Particle Size ◽

Aggregate Size ◽

Recycled Concrete ◽

Partial Replacement ◽

Rheological Parameters ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

General Terms ◽

Dynamic Yield ◽

Alkali Activated

The effect of two precursors (slag and fly ash), different particle size distribution, and three types of aggregate (siliceous sand, limestone, and recycled concrete) on alkali-activated material (AAM) mortar rheology were studied and compared to their effect on an ordinary Portland Cement (OPC) mortar reference. Stress growth and flow curve tests were conducted to determine plastic viscosity and static and dynamic yield stress of the AAM and OPC mortars. In both OPC and AAM mortars, a reduction of the aggregate size induces a rise of the liquid demand to preserve the plastic consistency of the mortar. In general terms, an increase of the particle size of the siliceous aggregates leads to a decrease of the measured rheological parameters. The AAM mortars require higher liquid/solid ratios than OPC mortars to attain plastic consistency. AAM mortars proved to be more sensitive than OPC mortars to changes in aggregate nature. The partial replacement of the siliceous aggregates with up to 20% of recycled concrete aggregates induced no change in mixing liquid uptake, in either AAM or OPC mortars. All the AAM and OPC mortars studied fitted to the Bingham model.

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Preliminary Study of Recycled Aggregate Mortar for Electric Arc Furnace Dust Encapsulation

Applied Sciences ◽

10.3390/app11209525 ◽

2021 ◽

Vol 11 (20) ◽

pp. 9525

Author(s):

Enrique F. Ledesma ◽

Angélica Lozano-Lunar ◽

Ruan L. S. Ferreira ◽

José María Fernández-Rodríguez ◽

José Ramón Jiménez

Keyword(s):

Fine Fraction ◽

Recycled Concrete ◽

Recycled Aggregate ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Natural Aggregate ◽

Before And After ◽

Preliminary Study ◽

Natural Aggregates ◽

Mechanical Strengths

This article shows the preliminary results of a study carried out to determine the technical feasibility of encapsulating a high percentage of EAFD in cement-based mortars manufactured with the fine fraction of recycled concrete aggregates (RCA). Two families of mortars, with natural aggregate as a reference and with RCA, were studied. An incorporation rate by weight of two parts mortar to one part EAFD was tested. The mechanical strengths (compressive strength and tensile strength) before and after immersion in water, the rate of delitescence and the leaching behavior were studied. Mortars made with RCA showed similar mechanical strengths to the reference mortars made with natural aggregates; however, the incorporation of EAFD decreased the mechanical strengths. Encapsulation considerably reduced the leaching of heavy metals, although the Pb concentration remained above the hazardous waste limit. With this preliminary study, two wastes are managed together, and the results have shown that the use of RCA instead of natural aggregate is a viable alternative since it does not significantly impair the mechanical or leaching properties of the cement-based matrices used to encapsulate EAFD.

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Mechanical Behavior of Hot-Mix Asphalt Made with Recycled Concrete Aggregates from Construction and Demolition Waste: A Design of Experiments Approach

Sustainability ◽

10.3390/su11133730 ◽

2019 ◽

Vol 11 (13) ◽

pp. 3730 ◽

Cited By ~ 5

Author(s):

Juan J. Galan ◽

Luís M. Silva ◽

Ignacio Pérez ◽

Ana R. Pasandín

Keyword(s):

Hot Mix Asphalt ◽

Water Saturation ◽

Recycled Concrete ◽

Construction And Demolition Waste ◽

Demolition Waste ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Natural Aggregate ◽

Indirect Tensile ◽

Natural Aggregates

The present work is a re-evaluation of previous research on the durability of hot-mix asphalt made with recycled concrete aggregates from construction and demolition waste (CDW) with a different approach. Response surface methodology (RSM) was used to conduct this study. The kind of natural aggregates (schist and calcite-dolomite), the recycled concrete aggregates percentage (0%, 20%, 40% and 60%) and the water saturation (0% and 100%) were the pertinent factors for this methodology. Indirect tensile stress (ITS) was determined in mixtures fabricated with 0%, 20%, 40% and 60% recycled concrete aggregates. According to the results, the ITS of the bituminous mixtures increases as the percentage of recycled concrete aggregate increases. This behavior is more significant when calcite-dolomite is used as a natural aggregate. Water saturation has the same influence in both natural aggregates. The indirect tensile strength ratio (ITSR) was calculated to evaluate the stripping potential. According to the Spanish specifications, the results suggest that the percentage of CDW that can be used for hot mixes is 17% when schist is used as natural aggregate and 14% for calcite-dolomite.

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Interlocking Pavement Tiles using RCA with Industrial Waste as Admixtures

Proceedings of International Web Conference in Civil Engineering for a Sustainable Planet ◽

10.21467/proceedings.112.52 ◽

2021 ◽

Author(s):

Anjana S ◽

Diya Elizabeth Isaac ◽

Neelanjana S ◽

Aswathy G

Keyword(s):

Fly Ash ◽

Industrial Waste ◽

Recycled Concrete ◽

Partial Replacement ◽

Normal Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Coarse Aggregates ◽

Loss Of Strength ◽

Enormous Quantity

The unprecedented increase in construction and developmental activities in the current era brings with it many irreversible impacts on the environment. The major impacts being the depletion of natural resources and generation of an enormous quantity of Construction and Demolition (C&D) wastes. Hence it has become important to reuse and recycle C & D wastes generated. These wastes can be processed to obtain Recycled Concrete Aggregates (RCA), which can be used for producing recycled concrete. It was found that the strength of Recycled concrete matches with that of paver quality concrete. Therefore, the study aims at producing interlocking paver blocks by replacing the normal coarse aggregates in pavers by RCA along with fly ash as admixture, an industrial waste. Fly ash being a pozzolanic admixture is used in order to overcome the loss of strength due to the addition of RCA. In the present study, a 30% replacement of normal aggregates with RCA and 15% replacement of cement with fly ash in the mix was used as it was found to provide the optimum strength. A comparison of the important properties of paver blocks were conducted between normal concrete pavers, pavers with RCA replacement and pavers with RCA replacement and fly ash. It was found out from the study that Interlocking pavers with partial replacement of normal aggregates with RCA and fly ash obtained strength comparable to that of normal paver blocks. Hence these paver blocks can be used for laying of roads and can contribute towards a sustainable development.

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Punching Behavior Of Self-Compacting Concrete Slabs Incorporating Coarse Recycled Concrete Aggregates

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol8.iss1.147 ◽

2020 ◽

Vol 8 (1) ◽

pp. 1-11

Author(s):

Malik K. E. Altaee ◽

Jamal A. S. Khudair

Keyword(s):

Reinforced Concrete ◽

Recycled Concrete ◽

Reduction Ratio ◽

Partial Replacement ◽

Concrete Slabs ◽

Hardened Concrete ◽

Self Compacting Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Maximum Reduction

This paper presents an experimental investigation on the effects of incorporating coarse recycled concrete aggregates (RCA) on the punching and flexural behaviour of reinforced concrete two-way slabs. For this purpose, four concrete mixes were designed with various substitution ratios of natural coarse aggregates (NCA) by RCA 0% (reference mix), 25, 50 and 75%. Subsequently, fourteen 800 × 800 mm × variable thickness reinforced concrete slabs (two per concrete type) were cast and subjected to punching and flexural tests. Different parameters that affect the behavior of two-way slabs were studied including type of failure, replacement ratios of NCA by RCA, amount of main reinforcement, thickness and loading patch size. In order to investigate the effect of RCA incorporation on hardened concrete properties (compressive strength Fcu, tensile Ft strength, flexural Fr strength and modulus of elasticity Ec), different replacement ratios were considered, while the quantity of cement was kept equaled for all the mixes (with and without RCA). Hardened concrete samples results showed that Fcu, Ft, Fr and Ec were decreased by (8.62, 13.54 and 19.12%), (13.08, 17.63 and 25.46%), (10.02, 21.67%, and 34.30%) and (9.69, 15.65 and 16.62%) respectively, for the (25, 50 and 75%) replacement ratios compared with samples made from SCC without RCA. The experimental results of slabs showed that the cracking and ultimate load (11% maximum reduction ratio) and moment (19.5% maximum reduction ratio) capacities of slabs were decreased compared with slabs made from SCC without RCA. Moreover, the load deflection curves were almost identical with proportional increase to the RCA content. From the general behavior, ultimate capacity, deflections, failure angle and crack pattern results, it can be concluded that the recycled concrete aggregate can be used as a partial replacement of natural coarse aggregate to produce self-compacting concrete mixes, where the behavior of two-way slabs cast with SCC containing RCA can considered acceptable.

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Impact of Long-Term Loading on Reinforced Concrete Beams Made with Partial Replacement of Coarse Aggregates with Recycled Aggregates from Old Concrete

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.2498 ◽

2019 ◽

Vol 9 (1) ◽

pp. 3818-3821 ◽

Cited By ~ 1

Author(s):

M. Oad ◽

A. H. Buller ◽

B. A. Memon ◽

N. A. Memon

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Recycled Concrete ◽

Reinforced Concrete Beams ◽

Partial Replacement ◽

Short Term ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Coarse Aggregates ◽

Sustained Loading

This research work presents an experimental evaluation of the effect of sustained loading on reinforced concrete beams made with 50% replacement of natural coarse aggregates with aggregates from old concrete. A total of 9 RC beams were cast, 6 with natural coarse aggregates and 3 with recycled concrete aggregates. All beams were cured for 28 days in standard fashion. Among the first batch, 3 beams were used to test under short term loading till failure. An application of 50% of short-term loading followed on all beams assembled on purpose made frames. All beams were monitored for deflection, strain, and cracking. Both deflection and strain remained within limits. Crack monitoring revealed maximum crack width 0.5 mm. After six months of sustained load, beams were removed from the frames and tested in universal load testing machine with central point load till failure. The load-deflection pattern of all beams was observed to be almost similar and 22.12% higher in recycled concrete beams than all-natural aggregate beams. The results show promising use of recycled concrete aggregates in new concrete subjected to sustained loading.

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Evaluation of Mechanical Characteristics of Cement Mortar with Fine Recycled Concrete Aggregates (FRCA)

Sustainability ◽

10.3390/su13010414 ◽

2021 ◽

Vol 13 (1) ◽

pp. 414

Author(s):

Rebeca Martínez-García ◽

María Isabel Sánchez de Rojas ◽

Julia Mª. Morán-del Pozo ◽

Fernando J. Fraile-Fernández ◽

Andrés Juan-Valdés

Keyword(s):

Research Work ◽

Chemical Characterization ◽

Recycled Concrete ◽

Partial Replacement ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Fine Aggregates ◽

Simple Processing ◽

Processing Techniques ◽

Physical And Chemical

One of the growing demands in concrete manufacture is the availability of natural fine aggregates, which account for 35% to 45% of the total concrete. An alternative method of disposal of fine recycled concrete aggregates (FRCA) generated from demolition and construction waste (C&DW) is their usage in mortar and the development of recycled mortar. The main aim of this research work is to evaluate the viability of incorporating FRCA from urban C&DW for the manufacture of cement-based mortars. Simple processing techniques like washing and sieving are adopted to improve the FRCA quality. Physical and chemical characterization of ingredients is carried out. In total four mixes of 1:3 (cement: sand) mortar with partial replacement of normalized sand with FRCA (0%, 25%, 50%, and 100%) are evaluated for mechanical properties. Water to cement ratio for all four mortar mixes are determined by fixed consistency. Mechanical and physical properties like density, compressive strength, and flexural strength are studied for various curing periods, and the result is that the optimum usage of FRCA is 25% based on a 90-day curing period.

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