Measuring the water absorption of recycled aggregates, what is the best practice for concrete production?

Recycled aggregates have high water absorption and crushing index. In order to improve the properties of recycled aggregates in concrete production, various treatments were used to modify the aggregates. In recent years, bio-deposition as a new treatment method of recycled aggregates was environmentally friendly. An improved method of bio-deposition was implemented to modify the properties of recycled mortar aggregates (RMA). O-bio-deposition is based on aerobic bacteria induced CaCO3 precipitation by respiration by varying the distance between the RMA and the bottom of the container and by adding an oxygen release compound to the culture solution that contains bacteria to promote the induction of CaCO3. First, the physical properties, including water absorption, crushing value, and apparent density, of the coarse RMA under different treatment methods were determined, and an o-bio-deposition treatment method was obtained. The fine RMA was treated and compared with the untreated RMA. Concretes were then prepared from the treated coarse RMA, and compressive strength and slump were determined. In addition, the effect of the o-bio-deposition treatment on the RMA surface and the micro-cracks of concretes were observed by scanning electron microscopy (SEM). It was found that the water absorption and crushing index of the coarse RMA treated by o-bio-deposition were reduced by 40.38 and 19.76% compared with untreated RMA, respectively. Regarding the concrete, the slump and the compressive strength (28 d) of concrete were increased by 115% and 25.3%, respectively compared with the untreated concrete.

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

Sustainability ◽

10.3390/su10113862 ◽

2018 ◽

Vol 10 (11) ◽

pp. 3862 ◽

Cited By ~ 2

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.

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EFFECT OF RECYCLED CONCRETE AGGREGATE QUALITY ON PROPERTIES OF CONCRETE

Journal of Green Building ◽

10.3992/1943-4618.15.2.57 ◽

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.

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Effects of Concrete Grades on Strength Characteristics of Metakaolin Modified Recycled Aggregate Concrete

Nigerian Journal of Technological Development ◽

10.4314/njtd.v18i3.3 ◽

2021 ◽

Vol 18 (3) ◽

pp. 184-193

Author(s):

A.U. Adebanjo ◽

B.I.O. Dahunsi ◽

J.O. Labiran

Keyword(s):

Specific Gravity ◽

Water Absorption ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Conventional Concrete ◽

Aggregate Concrete ◽

Concrete Production ◽

Aggregate Impact Value ◽

Control Samples

In this study, locally produced Metakaolin (MK) was used as an admixture in recycled aggregate concrete of grades M 25 and M 30. The content of MK varied from 0-15% at 5% intervals. The physical and mechanical properties (bulk density, specific gravity, water absorption, aggregate crushing value and aggregate impact value) of aggregates were determined, the chemical composition as well as reactivity of MK was evaluated using X-Ray Fluorescence (XRF) technique and modified Chappelle test. The workability (slump) and strength (compressive and split tensile) properties of fresh and hardened RAC were examined relative to that of conventional concrete. The results of the experiments revealed that the specific gravity (SG), water absorption and aggregate impact value of recycled aggregates (RA) were 2.23, 5.35% and 32%, respectively. The MK used had an optimum reactivity of 2060.8 mg of Ca(OH)2 fixed at a temperature of 660 oC. The slump values for M 25 and M 30 control specimens were 72 mm and 65 mm, respectively while the slump values of MK modified RAC decreased from 67-45 mm for M 25 and 55-35 mm for M 30 as MK increased from 0-15%. The 56th-day compressive strength of the control samples was 21.73 N/mm2 for M 25 and 26.8 N/mm2 for M 30, respectively, while RAC samples ranged from 14.96 - 17.04 N/mm2 for M 25 and 20.55 - 22.67 N/mm2 for M 30 whereas the split tensile strength for the control samples was 2.71 N/mm2 and 3.06 N/mm2 for the two grades in that sequence, while those of RAC ranged from 2.26-2.49 N/mm2 for M 25 and 2.62 – 2.84 N/mm2 for M 30. Despite the fact that metakaolin modified RAC had lower strength properties than conventional concrete, the use of 10% metakaolin as a RA modifier in concrete production will provide a sustainable alternative to conventional aggregates in concrete mix design.

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Strength and Water Absorption of Sustainable Concrete Produced with Recycled Basaltic Concrete Aggregates and Powder

Sustainability ◽

10.3390/su13116277 ◽

2021 ◽

Vol 13 (11) ◽

pp. 6277

Author(s):

Ibrahim Sharaky ◽

Usama Issa ◽

Mamdooh Alwetaishi ◽

Ahmed Abdelhafiz ◽

Amal Shamseldin ◽

...

Keyword(s):

Water Absorption ◽

Edge Length ◽

Recycled Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Partial Substitution ◽

Small Reduction ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Sustainable Concrete

In this study, the recycled concrete aggregates and powder (RCA and RCP) prepared from basaltic concrete waste were used to replace the natural aggregate (NA) and cement, respectively. The NA (coarse and fine) was replaced by the recycled aggregates with five percentages (0%, 20%, 40%, 60% and 80%). Consequently, the cement was replaced by the RCP with four percentages (0%, 5%, 10% and 20%). Cubes with 100 mm edge length were prepared for all tests. The compressive and tensile strengths (fcu and ftu) and water absorption (WA) were investigated for all mixes at different ages. Partial substitution of NA with recycled aggregate reduced the compressive strength with different percentages depending on the type and source of recycled aggregate. After 28 days, the maximum reduction in fcu value was 9.8% and 9.4% for mixtures with coarse RCA and fine RCA (FRCA), respectively. After 56 days, the mixes with 40% FRCA reached almost the same fcu value as the control mix (M0, 99.5%). Consequently, the compressive strengths of the mixes with 10% RCA at 28 and 56 days were 99.3 and 95.2%, respectively, compared to those of M0. The mixes integrated FRCA and RCP showed higher tensile strengths than the M0 at 56 d with a very small reduction at 28 d (max = 3.4%). Moreover, the fcu and ftu values increased for the late test ages, while the WA decreased.

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Theoretical analysis of water absorption kinetics of recycled aggregates immersed in water

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.124156 ◽

2021 ◽

Vol 302 ◽

pp. 124156

Author(s):

Kun Liang ◽

Yingjie Hou ◽

Jianchun Sun ◽

Xiaoguang Li ◽

Jiahong Bai ◽

...

Keyword(s):

Theoretical Analysis ◽

Water Absorption ◽

Recycled Aggregates ◽

Absorption Kinetics ◽

Kinetics Of

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Concrete Production of Hot Asphalt Using Recycled Aggregates CDW

Materials Science Forum ◽

10.4028/www.scientific.net/msf.881.346 ◽

2016 ◽

Vol 881 ◽

pp. 346-350 ◽

Cited By ~ 2

Author(s):

Luzana Leite Brasileiro ◽

Fátima Maria de Souza Pereira ◽

Pablo de Abreu Vieira ◽

José Milton Elias de Matos

Keyword(s):

Solid Waste ◽

National Policy ◽

Mechanical Tests ◽

Construction And Demolition Waste ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Demolition Waste ◽

Final Destination ◽

Natural Aggregate ◽

Concrete Production

Every year, there is a considerable increase in the exploitation of deposits to supply the market for aggregates. On the other hand, so does the production of solid waste from construction and demolition waste (CDW). In 2010 Brazil approved the PNRS (National Policy on Solid Waste), which sets out how the country should have their waste, encouraging recycling and sustainability. As an alternative to the above problem, this paper aims to investigate the feasibility of partial and total replacement of the asphalt concrete aggregates by recycled aggregates from CDW in order to reduce the environmental impacts caused by the operation of quarries and give an adequate final destination the residue produced by man in construction. Were carried out five (05) projects mixture of: the first (parameter of our research) used only natural aggregates (0% CDW) in the second, third and fourth replaced 25%, 50% and 75% respectively of natural aggregate by the recycled aggregate and the fifth and last, used only recycled aggregates (100% CDW). They carried out the characterization of the aggregates by means of physico-chemical and mechanical, analyzing them with reference based on specific standards paving. For mixtures, they calculated the volumetric parameters and performed mechanical tests of tensile strength and stability. The results indicate that the recycled aggregate, in a defined proportion, can replace the natural aggregate in the flexible pavements

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Water absorption and frost heaving of recycled aggregates

Proceedings of the Institution of Civil Engineers - Construction Materials ◽

10.1680/coma.11.00037 ◽

2013 ◽

Vol 166 (3) ◽

pp. 127-132 ◽

Cited By ~ 2

Author(s):

Vahid Ayan ◽

Joshua R. Omer ◽

Mukesh C. Limbachiya ◽

Seyed Masoud Nasr Azadani

Keyword(s):

Water Absorption ◽

Recycled Aggregates ◽

Frost Heaving

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Strength Development and Durability of Concrete Containing Recycled Roof Tile Aggregate

Recycling ◽

10.3390/recycling4030029 ◽

2019 ◽

Vol 4 (3) ◽

pp. 29

Author(s):

Alhagie Bakary Ceesay ◽

Shingo Miyazawa

Keyword(s):

Physical Properties ◽

Water Absorption ◽

Recycled Aggregate ◽

Crushed Stone ◽

Strength Development ◽

Freezing And Thawing ◽

Aggregate Concrete ◽

Roof Tile ◽

Concrete Production ◽

Low Strength

The use of recycled aggregate in new concrete has often been limited due to concerns over their quality and structural performance. This research aims to investigate the physical properties of recycled roof tile aggregate and its suitability for concrete production. Physical properties of recycled roof tile aggregate are compared to normal crushed stone aggregate. Effects of recycled roof tile aggregates on strength and durability of recycled roof tile concrete was compared with normal aggregate concrete using mechanical properties and durability tests. The experimental results showed that high water absorption and low strength of aggregate have a great effect on the workability and strength of the concrete containing recycled roof tile aggregate. Aggregate density, water absorption, crushing value and abrasion value of the recycled roof tile aggregate were found to be lower than crushed stone aggregate and concrete containing recycled roof tile aggregate had low strength and slow strength development. Similar durability performance of recycled roof tile aggregate concrete and normal aggregate concrete was observed except when exposed to freezing and thawing.

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Durability Studies on the Recycled Aggregate Concrete in China over the Past Decade: A Review

Advances in Civil Engineering ◽

10.1155/2019/4073130 ◽

2019 ◽

Vol 2019 ◽

pp. 1-19 ◽

Cited By ~ 6

Author(s):

Zhiming Ma ◽

Qin Tang ◽

Dingyi Yang ◽

Guangzhong Ba

Keyword(s):

Water Absorption ◽

Absorption Rate ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Rapid Urbanization ◽

Aggregate Concrete ◽

The Past ◽

Water Absorption Rate ◽

Average Water

Since China hosted the Olympic Games in 2008, a mass of construction and demolition (C&D) wastes were produced with the rapid urbanization construction. Recycling the C&D waste into recycled aggregates (RA) is an effective method for reducing the amount of C&D wastes. Many studies on the properties of RA and the durability of recycled aggregate concrete (RAC) were conducted in China over the past decade. Due to the restrictions of various languages, some valuable studies on the durability of RAC are hard to be acquired by the scholars around the world. Therefore, this paper is developed to review the studies on the durability of RAC in China, and the shrinkage behavior, chloride permeability, carbonation behavior, and freeze-thaw resistance of RAC are, respectively, introduced. Considering the waste concrete, bricks, and ceramics used in preparing RA are frequently mixed together in China, this study proposes an index of average water absorption rate to quantify the effects of RA types, quality, and replacement percentages on the durability of RAC. Meanwhile, the relationship between the average water absorption rate of RA and the durability parameters of RAC is established. Finally, the improving methods of RAC durability are introduced, and the RA particle shaping and carbonation modification are emphasized.

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