scholarly journals MECHANICAL AND PHYSICAL PROPERTIES OF RECYCLED AGGREGATES CONCRETE

2020 ◽  
Vol 29 (1) ◽  
pp. 259-274
Author(s):  
Mayara Turi Gerin ◽  
Almir Sales ◽  
Silvana De Nardin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Water Absorption ◽  
Experimental Tests ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Recycled Concrete Aggregates ◽  
Additional Water ◽  
Mixing Method ◽  
Natural Aggregates

Aggregate type - natural or recycled - governs a range of concrete properties (e.g. water absorption and workability). Knowing this, there are many recommended mixing methods for maintaining concrete workability. However, they may be not economic feasible or they may depreciate mechanical properties. In this work, four concrete mixtures were produced replacing 0, 30, 50 and 100% of natural aggregates by recycled concrete aggregates without any pre-wetting method or additional water. Instead of, the “Two-Stage Mixing Approach” mixing method was used. From the experimental tests it was possible to observe the influence of the substitution content on the workability, water absorption ability, density, voids index, compressive strength, tensile strength and modulus of elasticity.  In addition, the tensile strength and elastic modulus values of recycled concrete were also compared to those obtained in the equations recommended by ABNT NBR 6118:2014 for concrete with natural aggregates. The results showed that it is possible to maintain the workability of concrete without depreciating its mechanical properties.

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

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.

scholarly journals Modulus and Strength of Concretes with Alternative Materials

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4378
Author(s):  
Ana Elisabete Paganelli Guimarães de Avila Jacintho ◽  
Ivanny Soares Gomes Cavaliere ◽  
Lia Lorena Pimentel ◽  
Nádia Cazarim Silva Forti
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Model Code ◽  
Alternative Materials ◽  
Model Code 2010 ◽  
The Difference ◽  
Natural Aggregates ◽  
Predicted Values

This paper presents a study with concretes produced with natural aggregates, recycled concrete aggregates (RCA) and waste porcelain aggregates (WPA). The study analyzed the influence of recycled aggregates in the mechanical properties of conventional concretes and evaluated the difference between measured and predicted values of elasticity modulus. The incorporation of WPA in concrete showed better mechanical results compared to the concretes produced with RCA. Measured elasticity moduli were lower than moduli predicted by NBR 6118:2014 and fib Model Code 2010, while measured results were greater than values predicted by Eurocode 2:2004 and ACI 318:2014, as expected, which indicated the safety of the latter two standards.

Influence of the Crushing Process of Recycled Aggregates on Concrete Properties

2014 ◽  
Vol 634 ◽  
pp. 151-162 ◽  
Author(s):  
Diogo Pedro ◽  
Jorge de Brito ◽  
Luís Evangelista
Keyword(s):  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Efficient Production ◽  
Capillary Water ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Carbonation Resistance ◽  
Chloride Penetration Resistance ◽  
Durability Performance

This work intends to evaluate the (mechanical and durability) performance of concrete made with coarse recycled concrete aggregates (CRCA) obtained using two crushing processes: primary crushing (PC) and primary plus secondary crushing (PSC). This analysis intends to select the most efficient production process of recycled aggregates (RA). The RA used here resulted from precast products (P), with strength classes of 20 MPa, 45 MPa and 65 MPa, and from laboratory-made concrete (L) with the same compressive strengths. The evaluation of concrete was made with the following tests: compressive strength; splitting tensile strength; modulus of elasticity; carbonation resistance; chloride penetration resistance; capillary water absorption; and water absorption by immersion. These findings contribute to a solid and innovative basis that allows the precasting industry to use without restrictions the waste it generates.

scholarly journals Evaluation of Eco-Efficient Concretes Produced with Fly Ash and Uncarbonated Recycled Aggregates

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7499
Author(s):  
Miren Etxeberria
Keyword(s):  
Fly Ash ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Hardened Concrete ◽  
Conventional Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Carbonation Resistance ◽  
Chloride Resistance ◽  
Natural Aggregates

The fabrication of conventional concrete, as well as remains from demolition, has a high environmental impact. This paper assessed the eco-efficiency of concrete made with uncarbonated recycled concrete aggregates (RCA) and fly ash (FA). Two concrete series were produced with an effective water/cement ratio of 0.50 (Series 1) and 0.40 (Series 2). In both series, concretes were produced using 0% and 50% of RCA with 0%, 25% and 50% FA. After analysing the compressive strength, and carbonation and chloride resistance of those concretes, their eco-efficiency based on the binder intensity and CO2-eq intensity was assessed. We found that the use of 50% uncarbonated RCA improved the properties of concretes produced with FA with respect to using natural aggregates. The concrete made of 25% FA plus RCA was considered the most eco-efficient based on the tests of compressive, carbonation and chloride properties with the values of 4.1 kg CO2 m−3 MPa−1, 76.3 kg CO2 m−3 mm−1 year0.5 and 0.079 kg CO2 m−3 C−1, respectively. The uncarbonated RCA improved carbonation resistance, and FA improved chloride resistance. It can be concluded that the use of 50% un-carbonated RCA combined with FA considerably enhanced the properties of hardened concrete and their eco-efficiency with respect to concretes produced with natural aggregates.

scholarly journals Performance of Recycled Aggregate Concrete for M25 Grade Concrete

2019 ◽  
Vol 9 (2) ◽  
pp. 4694-4700
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete ◽  
Inorganic Particles ◽  
Natural Aggregates

Recycled aggregates (RCA) are the aggregates which are made up of crushed, inorganic particles that are obtained from the construction demolition debris. Now a day’s protection of environment is the ultimate challenge to the society. So the usage of RCA’s is the best alternative for the aggregates which are obtained naturally in the construction activity. The scope of using these recycled concrete aggregates is increasing day by day. It reduces the cost effectively as we are using waste concrete as recycled aggregates. The main focus of this paper is to use find the strength qualities of recycled aggregates so as to use it as an alternative for the natural aggregates in high strength concrete for various construction activities. Comparison of workability, compressive strength, tensile strength, elastic modulus and flexural strength of recycled aggregate concrete is made with natural aggregate concrete. Here M25 grade concrete is taken and the natural aggregates were replaced with recycled aggregates in various percentages of 0%, 25%, 50%, 75% and 100%. The mix design for these replacement ratios are done by using code of IS 10262-2009. In order to determine the properties which were mentioned above a total of 60 cubes, 10 beams and 40 cylinders were casted. The compressive strength and tensile strength of RCA concrete have been determined for 7 days and 28 days where as the modulus of elasticity and the flexural strength of RCA concrete are determined after curing for the period of 28 days. The tests done on RCA concrete are compared with concrete which is obtained by natural aggregates As per IS codification the parameters which were determined are reducing moderately as the amount of aggregates which are recycled is being raised

scholarly journals Experimental Investigation of Concrete with Recycled Aggregates for Suitability in Concrete Structures

2019 ◽  
Vol 9 (23) ◽  
pp. 5010
Author(s):  
Arkadiusz Denisiewicz ◽  
Małgorzata Śliwa ◽  
Krzysztof Kula ◽  
Tomasz Socha
Keyword(s):  
Experimental Investigation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Water Absorption ◽  
Frost Resistance ◽  
Experimental Tests ◽  
Strength Properties ◽  
Recycled Aggregates ◽  
Total Shrinkage ◽  
Structural Applications

This paper presents the experimental tests of concrete made on the recycled aggregates basis. Tests were carried out to determine the concrete suitability for construction purposes. The physical and strength properties were determined for three types of recycling aggregates. The aggregates were obtained from sanitary ceramics ‘SC’ (washbasins and toilet bowls), building ceramics ‘BC’ (solid bricks), and concrete rubble ‘CR’. The results obtained in tests of compressive strength, bending tensile strength, water absorption, total shrinkage, watertightness, and frost resistance of concrete made of SC and CR aggregates gave grounds for stating its suitability for structural purposes. Concrete based on the BC aggregates is not recommended for structural applications.

scholarly journals Natural aggregate totally replacement by mechanically treated concrete waste

2015 ◽  
Vol 10 (1) ◽  
pp. 83-90
Author(s):  
Jozef Junak ◽  
Nadezda Stevulova
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Reference Sample ◽  
Average Density ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregates ◽  
Recycled Material

Abstract This paper presents the results obtained from the research focused on the utilization of crushed concrete waste aggregates as a partial or full replacement of 4/8 and 8/16 mm natural aggregates fraction in concrete strength class C 16/20. Main concrete characteristics such as workability, density and compressive strength were studied. Compressive strength testing intervals for samples with recycled concrete aggregates were 2, 7, 14 and 28 days. The amount of water in the mixtures was indicative. For mixture resulting consistency required slump grade S3 was followed. Average density of all samples is in the range of 2250 kg/m3 to 2350 kg/m3. The highest compressive strength after 28 days of curing, 34.68 MPa, reached sample, which contained 100% of recycled material in 4/8 mm fraction and 60% of recycled aggregates in 8/16 mm fraction. This achieved value was only slightly different from the compressive strength 34.41 MPa of the reference sample.

New Concrete with Recycled Aggregates from Leftover Concrete

2015 ◽  
Vol 754-755 ◽  
pp. 389-394
Author(s):  
Ofelia Corbu ◽  
Attila Puskás ◽  
Andrei Victor Sandu ◽  
Adrian M. Ioani ◽  
Kamarudin Hussin ◽  
...  
Keyword(s):  
Concrete Strength ◽  
Ecological Impact ◽  
Experimental Tests ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
River Sand ◽  
Coarse Aggregates ◽  
Concrete Type ◽  
Natural Aggregates

We live in an era where people should be more aware of pollution and its consequences. The present paper reveals a way protecting the environment while producing high quality concrete. What make this type of concrete environmentally friendly are the recycled aggregates in the concrete composition amongst with eliminating the ecological impact by saving large amounts of natural aggregates resources. Recycling concrete comes with many other advantages that lead to waste reduction, economy in waste transportation and storage taxes, which are becoming increasingly expensive. This research is based on mix design and experimental tests carried out on C20/25 strength class concrete with uncontaminated leftover concrete aggregates (LCAgg). It reveals favorable results in order to militate for recycled concrete aggregate uses in regular concrete strength classes respectively for common structural elements, mainly for slabs. River sand (0/4 mm) and coarse aggregates (4/8 mm and 8/16 mm): natural sources or recycled concrete type-alternatively used in several mixes-were utilized in concrete mixes.

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.

Reuse of improved recycled concrete aggregates (RCA) for sustainable and environmental-friendly construction materials.

2021 ◽  
Author(s):  
Ahmad Sarhan Alyaseen ◽  
Siddharth Shah ◽  
Ravindra Solanki ◽  
Bhavik Daxini ◽  
Yogesh K. Alwani ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Industrial Development ◽  
Waste Treatment ◽  
Acetic Acid Solution ◽  
Construction Materials ◽  
Road Construction ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregates

Abstract Recycled aggregates have an essential role in constructing construction activities today to save natural aggregates because of industrial development. The research aims to assess the suitability of recycled aggregates for the construction of new roads, which will help achieve road construction efficiency and help prevent environmental deterioration in the extraction and reducing pollution. In contrast with natural aggregates, recycled aggregates are of lower quality, mainly due to the cement mortar's brittle nature attached to them. The point of the study is to increase the performance of RCAs in an environmentally friendly managing RCAs. In this process, RCAs are first soaked in acetic acid solution, in which acetic acid reacts with cement attached to the surface of the RCA. This reaction weakens the attached mortar and allows separating from the RCAs by using mechanical friction later. Treated RCAs have lower water absorption and more insufficient cement mortar adhesion. These RCAs used as aggregates in new the concrete increased the compressive strength, the tensile strength, and the concrete's flexural strength by 26%, 11%, and 26% at 28 days, respectively. It is clean, safe, efficient, and a new method to be applied, so no harmful products are used, and no dangerous substances are incorporated into the RCAs that are being treated. The waste treatment solution was used as a supplementary admixture construction, increasing the concrete's strength, and decreasing its environmental effects.

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