EFFECT OF RECYCLED CONCRETE AGGREGATE QUALITY ON PROPERTIES OF CONCRETE

2020 ◽  
Vol 15 (2) ◽  
pp. 57-69
Author(s):  
Daniel Hatungimana ◽  
Şemsi Yazıcı ◽  
Ali Mardani-Aghabaglou
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Recycled Concrete Aggregate ◽  
Waste Concrete ◽  
Concrete Production

ABSTRACT The possibility of the use of recycled aggregates from the construction industry in green concrete production is of increasing importance to reduce the negative environmental impact associated with construction and demolition wastes. The objective of this study is to investigate the effect of recycled concrete aggregate (RCA) quality on the properties of hardened concrete properties such as compressive strength, splitting tensile strength, density, water absorption capacity and porosity accessible to water. The RCA used in this study was obtained from the crushing of waste concrete with two different compressive strengths (LRCA obtained from the crushing of waste concrete having compressive strengths below 30 MPa and HRCA obtained from the crushing of waste concrete having compressive strengths above 30 MPa). The natural coarse limestone aggregate was 100% replaced with coarse LRCA and HRCA. As a result of the study, the use of 100% HRCA and %100 LRCA instead of limestone coarse aggregate in the concrete adversely affected its mechanical and physical properties. In addition, HRCA showed better performance in terms of compressive strength, tensile strength, water absorption and porosity compared to the use of LRCA. Furthermore, the percentage of adhered mortar on the surface of LRCA and HRCA was analyzed using a computerized micro tomography device, and it was found that the percentages of attached mortar and aggregates are 61% and 35.5% for LRCA, whilst the attached mortar and aggregate contents for HRCA are 45.9% and 53.7%, respectively.

scholarly journals The Influence of Discharge Time, Kind of Additive, and Kind of Aggregate on the Properties of Three-Stage Mixed Concrete

2018 ◽  
Vol 10 (11) ◽  
pp. 3862 ◽  
Author(s):  
Alena Sicakova ◽  
Karol Urban
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Discharge Time ◽  
Concrete Mixtures ◽  
Concrete Properties ◽  
Concrete Production ◽  
The Impact

Application of recycled aggregates (RA) for concrete production is limited due to their poor quality. While the environmental benefits of using the RA are well accepted, some unsolved problems prevent this type of material from wide application in structural concrete. The research and development of techniques which can minimize the adverse effect of RA on the concrete properties are highly requested. A specific mixing approach can also be helpful; here, mineral additives play a significant role for improvement of RA performance within the mixing process. However, delivery process can influence the homogeneity and uniformity of the concrete mixtures, resulting in negative effect on technical parameters. In this study, the impact of delivery time (0 min, 45 min, and 90 min) on the set of hardened concrete properties is presented while the three-stage mixing is used. Two kinds of additives—fly ash (FA) and recycled concrete powder (RCP)—were tested to coat the coarse fraction of recycled concrete aggregate (RCA) in the first step of mixing. For comparison, cement as coating material and natural aggregate instead the RCA were also used. The following parameters were tested after 28 days of setting and hardening: density, compressive strength, splitting tensile strength, water absorption capacity, and depth of penetration of water under pressure. Generally, 90 min of working with concrete mixtures left no significantly negative influence on tested characteristics. Based on ANOVA results, with prolonged discharge time, the changes in composition of the mixtures become less important for compressive strength, density, and water absorption.

scholarly journals Mechanical Properties of Concrete with Recycled Concrete Aggregate and Fly Ash

Recycling ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 23
Author(s):  
Ihab Katar ◽  
Yasser Ibrahim ◽  
Mohammad Abdul Malik ◽  
Shabir Hussain Khahro
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Tensile Tests ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Recycled Concrete Aggregate ◽  
Replacement Level ◽  
Split Tensile Strength ◽  
Hardened State

Recycled concrete aggregate (RCA) collected from the demolition of old reinforced concrete structures can be reused to prepare structural and non-structural concrete, thereby protecting the environment by preserving natural resources. This study explores RCA’s use, collected from the crushed concrete of different building projects in Riyadh, to manufacture fresh self-compacting concrete (SCC) and investigate its properties in the fresh and hardened state. Four SCC mixes were prepared by replacing natural aggregate (NA) with RCA at 0%, 25%, 50%, and 75% replacement levels. The water-cement (w/c) ratio was maintained constant at 0.38 for all the mixes. Slump Flow, J-ring, and V-funnel tests were performed on the SCC mixes in the fresh state, and the compressive strength of hardened concrete was determined after seven, 14, and 28 days. Water absorption and split tensile tests were also carried out for all the mixes. The findings revealed that it is possible to reach compressive strengths higher than 40 MPa at 28 days for RCA replacement level of 75% by using a superplasticizer and low w/c ratio. The decrease in compressive strength concerning the SCC-NA mix was 25% for 75% replacement level. The highest split tensile strength at 28 days was around 3.3 MPa for a 50% replacement level. The lowest water absorption was 3.2% for SCC-NA, which was gradually increased and was highest at 5.6% for 75% replacement level.

scholarly journals Toward the use of high volume recycled concrete aggregate in new concrete production

2021 ◽  
Author(s):  
Anto Sucic
Keyword(s):  
High Volume ◽  
Recycled Concrete ◽  
Mix Design ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Fresh Properties ◽  
Waste Concrete ◽  
Concrete Production ◽  
Hardened Properties ◽  
Recycled Material

This thesis reports the findings of a study carried out to determine the feasibility of using Recycled Concrete Aggregate (RCA) in the production of newly made concrete at high replacement levels of conventional coarse Virgin Aggregates (VA). The study evaluated the properties of new concrete produced with coarse RCA, in order to address the issues typically associated with the characteristics of the recycled material. Concrete specimens were tested for fresh properties, hardened properties, as well as overall durability of mixes. Making minor modifications in mix design, the drawbacks typically associated with the use of RCA were successfully mitigated at high replacement levels, making up to a full 100% replacement feasible. Through the use of higher replacement levels of RCA in the production of concrete, the environmental impacts of VA harvesting may be significantly reduced, as well as providing a more economical means of waste concrete disposal for ready mix producers.

Influence of Waste Paper Sludge Ash (WPSA) and Fine Recycled Concrete Aggregate (FRCA) on the Compressive Strength Characteristic of Foamed Concrete

2012 ◽  
Vol 626 ◽  
pp. 376-380 ◽  
Author(s):  
Siti Shahidah Sharipudin ◽  
Ahmad Ruslan Mohd Ridzuan
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Waste Paper ◽  
Paper Sludge ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Production ◽  
Foamed Concrete ◽  
Paper Sludge Ash ◽  
Sludge Ash

In the effort to produce sustainable concrete, considerable attempt has been placed on replacing the main ingredients in concrete mixtures with more sustainable materials with the objective to reduce the carbon footprint. One of the replacement materials is waste paper sludge ash (WPSA), a local industrial by-product generated abundantly by newsprint mills which possesses considerable cementitious properties. Parallel to this, the high amount of construction waste, particularly concrete waste has become a difficult environmental issue to cope with in todays world. For this reason, recycling of concrete waste as a new alternative aggregate is being effectively utilized in concrete production. Thus, this paper reports on a study conducted to evaluate the compressive strength characteristics of the potential of using WPSA as a binder and fine recycled concrete aggregate (FRCA) as a virgin sand replacement in producing foamed concrete. The findings of this study exhibited that the inclusion of WPSA and FRCA for replacement ratios up to 20% and 15% respectively has significantly influenced the strength properties of foamed concrete.

Effect of Recycled Concrete Aggregate Properties on Mixture Proportions of Structural Concrete

2012 ◽  
Vol 2290 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Liam Butler ◽  
Jeffrey S. West ◽  
Susan L. Tighe
Keyword(s):  
Compressive Strength ◽  
Water Demand ◽  
Coarse Aggregate ◽  
Cement Content ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Recycled Concrete Aggregate ◽  
Aggregate Properties ◽  
Equivalent Control

This study focuses on characterizing several recycled concrete aggregate (RCA) sources, developing concrete mixture proportions that incorporate RCA as coarse aggregate, and investigating the effect of coarse aggregate properties on the main mixture proportion parameters [i.e., cement content, water demand, and water–cement (w/c) ratio]. Four aggregate types were investigated: one control virgin aggregate source and three RCAs produced from the crushing of hardened concrete. Numerous aggregate tests, including density, absorption, abrasion resistance, adhered mortar content, and crushing value, were performed. Fourteen mixture proportions were developed with the use of three mixture proportion scenarios (control, direct replacement, and strength based) and two compressive strength levels (40 and 60 MPa). The effect of RCA on compressive strength and workability was evaluated by replacement of natural coarse aggregate with RCA. Contrary to numerous studies, one of the RCA concretes (RCA-1) had compressive strengths up to 12% higher than the equivalent control mixture. Mixture proportions (water, cement, and w/c ratio) were later adjusted to ensure that the RCA concretes had compressive strength and slump values similar to the control concretes. Variations in water demand, cement content, and w/c ratio could then be directly attributed to the properties of the RCA source. RCA-1 concrete required less cement (and a higher w/c ratio) to achieve strengths and slumps similar to the control concrete. The findings and recommendations of this research will assist concrete producers, engineers, and field technicians involved in the selection of RCA sources in developing mixture proportions for structural-grade RCA concrete.

scholarly journals Toward the use of high volume recycled concrete aggregate in new concrete production

2021 ◽  
Author(s):  
Anto Sucic
Keyword(s):  
High Volume ◽  
Recycled Concrete ◽  
Mix Design ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Fresh Properties ◽  
Waste Concrete ◽  
Concrete Production ◽  
Hardened Properties ◽  
Recycled Material

This thesis reports the findings of a study carried out to determine the feasibility of using Recycled Concrete Aggregate (RCA) in the production of newly made concrete at high replacement levels of conventional coarse Virgin Aggregates (VA). The study evaluated the properties of new concrete produced with coarse RCA, in order to address the issues typically associated with the characteristics of the recycled material. Concrete specimens were tested for fresh properties, hardened properties, as well as overall durability of mixes. Making minor modifications in mix design, the drawbacks typically associated with the use of RCA were successfully mitigated at high replacement levels, making up to a full 100% replacement feasible. Through the use of higher replacement levels of RCA in the production of concrete, the environmental impacts of VA harvesting may be significantly reduced, as well as providing a more economical means of waste concrete disposal for ready mix producers.

scholarly journals Mechanical Behavior of Fine Recycled Concrete Aggregate Concrete with the Mineral Admixtures

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2264
Author(s):  
Minkwan Ju ◽  
Jae-Gwon Jeong ◽  
Martin Palou ◽  
Kyoungsoo Park
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Performance ◽  
Total Porosity ◽  
Recycled Concrete ◽  
Mineral Admixtures ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
The Relationship ◽  
Normal Dosage

The paper describes the mechanical behavior of fine recycled concrete aggregate (FRCA) concrete according to the mineral admixtures. Three types of the mineral admixtures, i.e., fly ash (FA), ground-granulated blast-furnace slag (GGBS), and silica fume (SF), are used and the replacement ratios of FRCA are 50% and 100%. The dosages of the admixtures of FA, GGBS, and SF are determined with the normal dosage (30%, 40%, and 5.0%, respectively) based on the ACI committee reports (No. 232, 233, and 234) and half-normal dosage. The mechanical performance is investigated with the compressive and splitting tensile strength, and elastic modulus. Additionally, the total porosity is measured in natural fine aggregate (NFA) and FRCA 100% replaced specimens by mercury intrusion porosimetry (MIP) for investigating the relationship with the compressive strength. Based on the experimental test results, the mineral admixtures improve the mechanical performance of FRCA concrete. The effective dosages of FA, GGBS, and SF for FRCA concrete are investigated according to the replacement ratio of the FRCA. In particular, FRCA 100% replaced concrete may be possible to be used for the structural concrete members with the specific dosage of the mineral admixtures. The prediction of the splitting tensile strength and the elastic modulus by the codes or previous formulas exhibits underestimated and overestimated results, respectively. The relationship between the total porosity and the compressive strength of the FRCA concrete should be modified with more experimental tests.

scholarly journals Properties of Concrete with Recycled Concrete Aggregate Containing Metallurgical Sludge Waste

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1448 ◽  
Author(s):  
Jan Pizoń ◽  
Jacek Gołaszewski ◽  
Mohamed Alwaeli ◽  
Patryk Szwan
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Recycled Concrete Aggregate ◽  
Metallurgical Waste ◽  
Illegal Mining ◽  
Marine Sand ◽  
Sludge Waste ◽  
Natural Aggregates

Sand has been considered to be something of an immeasurable quantity. There are many indications that this view is no longer valid and that the limiting of natural aggregates usage is doubly justified. Firstly, the extraction of natural aggregates is expensive and has a huge impact on the environment. The main issues in sand and gravel mining are the large areas that are affected, ground water level changes, illegal mining, unsuitability of desert and marine sand, and costs of transport. Secondly, metallurgical waste can be used as a substitute for natural aggregates. This is doubly beneficial—the waste is recycled and the use of natural aggregates is reduced. Waste is stored in landfills that take up large areas and there is also the possibility of ground and groundwater pollution by hazardous compounds. The research presented in this article focuses on the technological conditions of using metallurgical waste in its original form and as a component of recycled concrete aggregate (RCA). The use of metallurgical sludge waste or crushed or round RCA to produce concrete deteriorates the consistency and does not significantly affect the air content and density of the concrete mix. RCA lowers the density of hardened concrete. Metallurgical sludge waste or RCA usage adversely affect the absorbability and permeability of concrete. Concrete containing metallurgical sludge waste is of higher compressive strength after 7 and 28 days, with up to 60% of waste as a sand replacement. RCA concrete achieved higher compressive strength also.

scholarly journals Experimental Study on Self Compacting Fibrous Concrete Comprising Magnesium Sulphate Solution Treated Recycled Aggregates

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 340
Author(s):  
Parthiban Kathirvel ◽  
Gunasekaran Murali ◽  
Nikolai Ivanovich Vatin ◽  
Sallal R. Abid
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Magnesium Sulphate ◽  
Steel Fibre ◽  
Recycled Concrete ◽  
Sulphate Solution ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Split Tensile Strength

It appears that the awareness and intentions to use recycled concrete aggregate (RCA) in concrete are expanding over the globe. The production of self-compacting concrete (SCC) using RCA is an emerging field in the construction sector. However, the highly porous and absorptive nature of adhered mortar on RCA’s surface leads to reduced concrete strength, which can be removed with the application of various techniques, such as acid treatment. This study investigated the effect of the partial replacement of silica fume by cement and natural aggregate (NA) by RCA with and without steel fibre. The used RCA was treated with magnesium sulphate solution. It was immersed in solutions with different concentrations of 10%, 15% and 20% and for different periods of 5, 10 and 15 days. Sixteen mixes were prepared, which were divided into six groups with or without 1% of steel fibre content. The fresh properties, compressive strength, split tensile strength and impact resistance were examined. The results revealed that the strengths of the mixes with 20% RCA were marginally better than those of the control mixes. The compressive strength and split tensile strength were reduced by 34% and 35% at 60% RCA content, respectively, as compared to the control mixes.

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