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.

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 Properties of Concrete Prepared with Recycled Aggregates Treated by Bio-Deposition Adding Oxygen Release Compound

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2147 ◽  
Author(s):  
Yaguang Zhu ◽  
Quanquan Li ◽  
Peizhen Xu ◽  
Xiangrui Wang ◽  
Shicong Kou
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
High Water ◽  
Treatment Method ◽  
Recycled Aggregates ◽  
Culture Solution ◽  
Oxygen Release ◽  
Micro Cracks ◽  
Concrete Production ◽  
New Treatment

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.

scholarly journals Reusing of Construction Debris in Plain Concrete Elements

2021 ◽  
Vol 9 (3) ◽  
pp. 81-87
Author(s):  
A. Abdelrahman Abuserriya ◽  
B. Bashir H. Osman ◽  
C. Salma Y. Mahmoud
Keyword(s):  
Compressive Strength ◽  
Sea Water ◽  
Plain Concrete ◽  
Absorption Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Content ◽  
Concrete Production ◽  
Concrete Blocks

Construction is a serious environmental problem and a challenge for people who concerned with sustainability in the construction field. Previous studies showed positive results for the use of recycled aggregates in the concrete production. This study portrays the results for utilizing construction debris for casting different types of concrete blocks. The recycled concrete debris was used in different ratios (0%, 50%, and 100%) in replacement for natural coarse aggregates for different targeted compressive strength (B250, B300, B350 and B400). Two types of water (pure and sea water) were used for curing the blocks. In addition, hollow block and paving block were casted with different ratios of recycled aggregate (0%, 20%, 45% and 100%) and cured with two types of water. The results showed a decrease in compressive strength with the increase recycled aggregate content. It was also noticed that the absorption capacity increases with high recycled aggregate content.  

scholarly journals A Study Based upon the Usage Recycled Aggregate to Enhance the Strength Aspects of Conventional Concrete: A Critical Review

2021 ◽  
Vol 9 (VI) ◽  
pp. 1567-1570
Author(s):  
Suhail Mushtaq Khan
Keyword(s):  
Chloride Ions ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Split Tensile Strength ◽  
Conventional Concrete ◽  
Natural Aggregate ◽  
Concrete Production

Recycled aggregates are those crushed cement concrete or asphalt pavement which comes out from the construction debris which is reused in construction. They are made from the reprocessing of materials which have been used in previous constructions. This paper discusses about the study of properties of recycled aggregates from the sources which has already been published. The results are that 100% replacement of natural aggregate by recycled concrete aggregate effect on chloride ions resistance, it plays negative effects on durability of recycled concrete aggregates, and addition of fiber in recycled aggregate concrete mixture gave more effective in the performance of concrete. On experimental study of recycled aggregate, compressive, flexural and split tensile strength of the recycled aggregate were found to be lower than that of the natural aggregate. Use of recycled aggregate in a new concrete production is still limited. Recommendation of introduction of recycled aggregates standard is required for the materials to be used successfully in future. Gaps in literature reviews are also included in this paper.

scholarly journals Recycled aggregate amount variation of fraction 4/8 mm and 8/16 mm in the concrete mixture

2020 ◽  
Vol 15 (2) ◽  
pp. 49-54
Author(s):  
Jozef Junák ◽  
Natália Junáková
Keyword(s):  
Compressive Strength ◽  
Reference Sample ◽  
Point Of View ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Economic Point ◽  
Aggregate Fractions ◽  
Aggregate Amount

AbstractThe introductory part of the paper is devoted to the classification of aggregates according to various criteria, one of them is the geographical origin of aggregates. From the point of view of the circular economy, the use of recycled aggregates comes to the fore, mainly from the ecological point of view but also from the economic point of view.The paper summarizes the results of research focused on the variation of the amount of 2 Recycled concrete aggregate fractions in concrete, followed by an evaluation of the effect of the presence of recycled material in the mixture on the selected property, specifically compressive strength. The highest compressive strength 34.7 MPa after 28 days hardening reached sample containing 100% recycled fraction 4/8 mm, and 60% recycled fraction 8/16 mm. This value is only slightly different from the compressive strength of the reference sample (34.4 MPa).

scholarly journals Long-term performance of sustainable pavements using ternary blended concrete with recycled aggregates

2021 ◽  
Author(s):  
Gilson Lomboy ◽  
Douglas Cleary ◽  
Seth Wagner ◽  
Yusef Mehta ◽  
Danielle Kennedy ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Concrete Aggregates ◽  
Concrete Mixtures

Dwindling supplies of natural concrete aggregates, the cost of landfilling construction waste, and interest in sustainable design have increased the demand for recycled concrete aggregates (RCA) in new portland cement concrete mixtures. RCA repurposes waste material to provide useful ingredients for new construction applications. However, RCA can reduce the performance of the concrete. This study investigated the effectiveness of ternary blended binders, mixtures containing portland cement and two different supplementary cementitious materials, at mitigating performance losses of concrete mixtures with RCA materials. Concrete mixtures with different ternary binder combinations were batched with four recycled concrete aggregate materials. For the materials used, the study found that a blend of portland cement, Class C fly ash, and blast furnace slag produced the highest strength of ternary binder. At 50% replacement of virgin aggregates and ternary blended binder, some specimens showed comparable mechanical performance to a control mix of only portland cement as a binder and no RCA substitution. This study demonstrates that even at 50% RCA replacement, using the appropriate ternary binder can create a concrete mixture that performs similarly to a plain portland cement concrete without RCA, with the added benefit of being environmentally beneficial.

scholarly journals The Effect of Mixing Technique and Prolonged Mixing Time on Strength Characteristics of Concrete

Proceedings ◽  
2018 ◽  
Vol 2 (20) ◽  
pp. 1290
Author(s):  
Karol Urban ◽  
Alena Sicakova
Keyword(s):  
Compressive Strength ◽  
Mixing Time ◽  
Strength Properties ◽  
Recycled Concrete ◽  
Strength Characteristics ◽  
Concrete Aggregate ◽  
Splitting Strength ◽  
Mixing Method ◽  
Tensile Splitting Strength ◽  
The Impact

The experiment aims to test the triple mixing (3M) technique to produce the concrete with recycled concrete aggregate (RCA). Then, the impact prolonged mixing, representing the influence of delivery and discharge time in praxis, is analysed by the change in strength properties. Both the 28-day compressive strength and tensile splitting strength are evaluated in two aspects: the prolonged mixing time (0, 45 and 90 min after initial mixing), and the mixing method (normal and triple). Prolonged mixing time brought both the positive and negative changes in strength characteristics however the worst difference between initial mixing (0′) and 90′ minutes of mixing was only 8.4% for compressive strength and 8.5% for tensile splitting strength.

Influence of Morphology of Cathode-Ray Tube Glass as Coarse Aggregates on Compressive Strength and Water Absorption of Concrete

2018 ◽  
Vol 280 ◽  
pp. 399-409
Author(s):  
Nurul Noraziemah Mohd Pauzi ◽  
Maslina Jamil ◽  
Roszilah Hamid ◽  
Muhammad Fauzi Mohd Zain
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Coarse Aggregate ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Coarse Aggregates ◽  
Concrete Properties ◽  
Concrete Production ◽  
Cathode Ray Tube ◽  
Texture Size

The study on the substitution for natural coarse aggregates using waste CRT funnel glass in spherically shapes is still limited. In this paper, the waste CRT glass has been processed to form a spherical CRT glass (GS) and crushed CRT glass (GC), which were used as a coarse aggregate in concrete production. Results indicated that the inclusion of GS and GC has lower the compressive strength and decreased the rate of capillary water absorption of concrete. It was demonstrated that the morphology properties of GS and GC (shape, surface texture, size, grading) is significantly affected the concrete properties.

scholarly journals Experimental Research on Strength of Concrete Prepared by using Coarse Aggregate from Concrete Debris

2019 ◽  
Vol 8 (6S3) ◽  
pp. 1533-1537
Keyword(s):  
Coarse Aggregate ◽  
Economic Benefits ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Main Role ◽  
Fine Aggregate ◽  
Investment Funds ◽  
Waste Transfer ◽  
The Impact

Cement is the blend of cement, fine aggregate, coarse aggregate with addition of water. In this coarse aggregate plays the main role. But the resources of coarse aggregate get reduces day by day. So we have to found out the alternate way. The complete quantum of waste from development industry is evaluated to be 12 to 14.7 million tons for each annum out of which 7 to 8 million tons are concrete and block squander in India. These days, practically all obliterated cement has been for the most part dumped to landfills. As concrete is a basic, masscreated material in the development business, endeavours have been made to reuse and to monitor it. Solid reusing have as of late turned out to be significant parts of the development business. Solid reusing can be cultivated by reusing solid items, and after that prepared into optional crude materials as filling materials, street bases and sub bases or total for the creation of new concrete. The utilization of reused totals from development and destruction squanders is indicating planned application in development as option in contrast to essential totals. It preserves regular assets and lessens the space required for the landfill transfer. Recycled aggregates are comprised of crushed and graded materials that have been utilized in the development. The point of our research is to decide the characteristic quality of reused totals for application in basic individuals, which can give a superior comprehension on the properties of reused totals as an alternate material to coarse aggregate in structural elements. By using this material the area for damping the concrete debris in the landfills and the emission of CO2 during the mining of the aggregates can be minimized. Reduces the impact on landfills by which the land area can be used for other useful purposes like construction of transmission towers, mobile towers etc., Makes the cost investment funds in the transportation of total, and waste items and in waste transfer. There are both environmental and economic benefits of using recycled concrete aggregate

scholarly journals Analysis of compressive strength of concrete prepared by triplemixing technology depending on both the discharge and curing time

2018 ◽  
Vol 13 (1) ◽  
pp. 113-121
Author(s):  
Karol Urban ◽  
Alena Sicakova
Keyword(s):  
Compressive Strength ◽  
Fine Fraction ◽  
Coating Material ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Curing Time ◽  
Discharge Time ◽  
Compressive Strength Of Concrete ◽  
Prolonged Discharge

Abstract Compressive strength of concrete having recycled concrete aggregate is influenced by the properties and amount of those aggregate. The worse quality of RCA can be eliminated by specific mixing approach. Practical mixing and delivery of concrete could affect the properties of ready concrete due to prolonged time. In this paper, both the fly ash and fine fraction of recycled concrete were used to improve the quality of concrete due to coating of RCA, while the triple mixing technology was applied for this purpose. The compressive strength is evaluated from two aspects: the curing time (2, 28 and 90 days) and discharge time (0, 45 and 90 minutes after mixing) with attention being paid to the type of aggregate and the type of coating material. When using triple mixing technology, prolonged discharge time brings only small effect on the compressive strength (up to 12%) both in positive and negative way, depending on kind of coating material.

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