scholarly journals Pre-Wetting of Recycled Concrete as Alternative of Chemical, Natural and Industrial Waste Additives

2019 ◽  
Vol 8 (12) ◽  
pp. 743-748
Keyword(s):  
Compressive Strength ◽  
Analytical Study ◽  
Recycled Concrete ◽  
Silica Sand ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Recycled Concrete Aggregate ◽  
Arab Region ◽  
Super Plasticizer ◽  
Day By Day

Destructive infrastructure is increasing day by day due to the successive wars in the Arab region and this led to the formation of large volumes of demolished concrete, which produces a lot of waste materials and visual pollution in the spaces. Meanwhile, environmental protection has become a challenge, not an option. As well as, reusing of demolished concrete in new structures is necessary to preserve the raw resources of aggregate away from attrition. Seventy-two specimens of ( 100 x 100 x 100 mm ) were prepared with water to cement ( W/C ) ratio of 0.4, where have replaced the different proportions of natural aggregate ( NA ) ( 0%, 30%, 45%, and 60% ) by recycled concrete aggregate ( RCA ), and then were added 2.5% super plasticizer ( SP ) in place of cement to other specimens according to previous replacement proportion of RCA to determine the optimum percentage of RCA and to investigate the effectiveness of using Super Plasticizer. The replacement proportion of RCA were 45% of NA. sixty six cubes of 45% - RCA were prepared with a different proportions of 0, 10, 15, and 20 % of instead of a fine aggregate for each the Iron Filler ( IF ) and Al-Qawirah Silica Sand (QSS), it is natural Silica was got from the quarry of AL-Qawirah, Jordan. The use of this type of silica as a substitute for fine aggregate with RCA is the first use in Jordan. The final stage of research was the pre-wetting of RCA by 0%, 2.5%, 5%, and 7.5% as percentage of W/C, it is an extra water added to the 45%-RCA mixtures before an hour from mix process, thirty-six cubes were casted with different proportions of extra water. The results displayed that the workability was reduced by increasing the RCA, while the workability was increase as ratios of W/C increase. The analytical study shows a considerable enhancement of the compressive strength of 2.5% pre-wetting of RCA with 45%-RCA relative to the SP, IF, and NA, where the increase in the compressive strength was 64% and 28% at 2.5% pre-wetting of RCA relative to SP-45% RCA and NA, respectively

Recycling of Waste Concrete and Fly Ash for Recycled Aggregate Concrete: Fundamental Characteristics Evaluation

2009 ◽  
Vol 620-622 ◽  
pp. 255-258 ◽  
Author(s):  
Cheol Woo Park
Keyword(s):  
Fly Ash ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Recycled Concrete Aggregate ◽  
Aggregate Concrete ◽  
Waste Concrete

As the amount of waste concrete has been increased and recycling technique advances, this study investigates the applicability of recycled concrete aggregate for concrete structures. In addition fly ash, the industrial by-product, was considered in the concrete mix. Experimental program performed compressive strength and chloride penetration resistance tests with various replacement levels of fine recycled concrete aggregate and fly ash. In most case, the design strength, 40MPa, was obtained. It was known that the replacement of the fine aggregate with fine RCA may have greater influence on the strength development rather than the addition of fly ash. It is recommended that when complete coarse aggregate is replaced with RCA the fine RCA replacement should be less than 60%. The recycled aggregate concrete can achieve sufficient resistance to the chloride ion penetration and the resistance can be more effectively controlled by adding fly ash. It I finally conclude that the recycled concrete aggregate can be successfully used in the construction field and the recycling rate of waste concrete and flay ash should be increased without causing significant engineering problems.

Utilization of Fine Recycled Aggregate and the Calcareous Fly Ash in CLSM Manufacturing

2014 ◽  
Vol 1054 ◽  
pp. 199-204 ◽  
Author(s):  
Wojciech Kubissa ◽  
Roman Jaskulski ◽  
Jacek Szpetulski ◽  
Anna Gabrjelska ◽  
Ewelina Tomaszewska
Keyword(s):  
Fly Ash ◽  
Fine Fraction ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Recycled Concrete Aggregate ◽  
River Sand ◽  
Wide Range ◽  
Strength Material

In the article the possibility of utilization of two waste materials: Recycled Concrete Aggregate (RCA) fraction 0-2 mm and Class C fly ash (from lignite burning power plant) in Controlled Low-Strength Material (CLSM) was presented. The research covered twelve different mixtures. The mixtures differed in cement and fly ash content as well as content of the fine aggregate. As a fine aggregate 0-2 mm fraction of RCA or river sand were used. The results showed that use the fine fraction RCA instead of sand does not cause technological problems and allows, depending on the needs, obtaining the material with different properties and a wide range of applications.

scholarly journals Evaluation of the Feasibility of Recycled Concrete Aggregate for Producing Structural Concrete

2020 ◽  
Vol 220 ◽  
pp. 01098
Author(s):  
Mohammad Tabrez Ali ◽  
Ibadur Rahman ◽  
Nirendra Dev ◽  
Priyanka Singh
Keyword(s):  
Compressive Strength ◽  
Construction Materials ◽  
Recycled Concrete ◽  
Environmental Benefits ◽  
Mix Design ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Structural Concrete ◽  
Average Value ◽  
Maximum Compressive Strength

When sustainability has become a primary measure of the selection of the building materials in the construction industry over the past decades, researchers all around the world have been looking upon for alternatives to reduce the overall environmental impact of the construction materials while not compromising the strength and durability. The factors like manufacturing, reusability, recyclability, disposal etc, are the criteria of utmost attention affecting the overall life cycle impact of the construction materials. In this prospect the Recycled Concrete Aggregate (RCA) has shown up as an exceptionally viable contender for the manufacturing of concrete with several environmental benefits over the Natural Aggregate (NA) and has already been identified by industry and several government agencies across the globe. The efficient material use of RCA can potentially deliver an inferior though competent concrete in comparison to the NA while averring the criteria of sustenance. The present study delves into the calculation of the proportion of the RCA in a mix design for achieving maximum compressive strength. The experimental setup constituted the casting of concrete cubes of control mix design of M40 grade with proportions of RCA varying from 0-100 percent spread over a space of 10% with NA which were later put to tests. The thorough investigation on the casted concrete cubes lead to the conclusion that the mix design with 50% proportion of RCA in addition to 50% proportion of NA delivered the maximum compressive strength, an average value of 8.23% higher than that of the normal concrete and the highest Rebound Number, an average value of 53.92 for the M40 grade concrete thereby showcasing the feasibility of producing structural concrete with RCA. The results are asserted to be governed by the better bonding between the RCA and NA and due to the significant increase in the water retention capacity by the provision of RCA in the mix.

Properties of Dry-Mortar with Recycled Concrete Aggregate and Powder of Crushed Clay Bricks

2011 ◽  
Vol 374-377 ◽  
pp. 1637-1640
Author(s):  
Jian Hua Xue ◽  
Xiao Guang Li ◽  
Yun Xiao Liu ◽  
Qiang Du
Keyword(s):  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Mass Ratio ◽  
Clay Brick ◽  
Natural Sand ◽  
Clay Bricks

Recycled concrete aggregate (RCA) and crushed clay bricks (CCB) have been increasingly researched and used in past two decades. However, studies focusing on the properties of dry-mortar with RCA and CCB are very limited. In this research, results from physical and mechanical properties of recycled mortar with fine recycled aggregate (FRA), fine recycled powder (FRP) and crushed clay brick (CCB) were secured. It is shown that sinking degree of FRA mortar can be adjusted in the range of 70-90mm and their water-maintainability is superior to natural sand mortar. However, compressive strength of FRA mortar at various ages decrease, compared to natural sand mortar under the condition of same mixed proportion. Compressive strength of FRA mortar is above 5.0MPa with mass ratio of aggregate to cement lower than 6.0.Workability of FRP and CCB mortar is similar to fly ash mortar and their apparent densities are under the 2.0g/cm3. Compressive strength of FRP and CCB mortar is near to 8.5 MPa at 28 days of age.

scholarly journals Untitled ItemProperties of Concrete Containing Recycled Concrete Aggregate of Preserved Quality

2021 ◽  
Author(s):  
Medhat Shehata ◽  
Jonathan Andal ◽  
Philip Zacarias
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
High Quality ◽  
Salt Scaling ◽  
Comparable Quality ◽  
Scaling Resistance

<p>This study focuses on evaluating recycled concrete aggregate (RCA) of high quality produced through a protocol that preserves the original properties of the concrete to be recycled. Concrete with RCA of preserved quality was compared to concrete with commercially available RCA. A total of 29 mixes were tested with RCA replacement ranging from 30% to 100% of the coarse aggregate. Results showed that concrete with RCA of preserved quality performed significantly better in compressive strength, drying shrinkage, and salt scaling resistance. Furthermore, the use of 30% RCA with preserved quality produced concrete of comparable quality to that of concrete with natural aggregate.</p>

scholarly journals Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

2018 ◽  
Vol 68 (330) ◽  
pp. 158 ◽  
Author(s):  
P. Rattanachu ◽  
I. Karntong ◽  
W. Tangchirapat ◽  
C. Jaturapitakkul ◽  
P. Chindaprasirt
Keyword(s):  
Compressive Strength ◽  
Negative Impact ◽  
Pore Space ◽  
High Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Crushed Limestone

This research aimed to use of bagasse ash as a cement replacement in high-strength recycled aggregate concrete (HS-RAC). Crushed limestone was replaced with 100% recycled concrete aggregate (RCA) and the ground bagasse ash (GBA) was used to partially replace ordinary Portland cement (OPC) at 20, 35 and 50%wt of binder to cast HS-RAC. The results indicated that the replacing of crushed limestone with RCA had a negative impact on the properties of the concrete. Increasing the amount of GBA in HS-RAC resulted in a decrease in density and an increase in the volume of permeable pore space. The concrete mixtures prepared with 20%wt GBA replacement of OPC promoted greater the compressive strength than the conventional concrete (CT concrete) at 90 days or more. HS-RAC with GBA (up to 50%) was more durable in terms of chloride ion penetration resistance, although it had lower compressive strength than the CT concrete.

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.

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