scholarly journals Effects of Steel Fibers (SF) and Ground Granulated Blast Furnace Slag (GGBS) on Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7497
Author(s):  
Jawad Ahmad ◽  
Rebeca Martínez-García ◽  
Maciej Szelag ◽  
Jesús de-Prado-Gil ◽  
Riadh Marzouki ◽  
...  
Keyword(s):  
Acid Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Optimum Dose ◽  
Split Tensile Strength ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Concrete Production ◽  
Dry Shrinkage ◽  
Furnace Slag

Recycled aggregate is a good option to be used in concrete production as a coarse aggregate that results in environmental benefits as well as sustainable development. However, recycled aggregate causes a reduction in the mechanical and durability performance of concrete. On the other hand, the removal of industrial waste would be considerably decreased if it could be incorporated into concrete production. One of these possibilities is the substitution of the cement by slag, which enhances the concrete poor properties of recycled aggregate concrete as well as provides a decrease in cement consumption, reducing carbon dioxide production, while resolving a waste management challenge. Furthermore, steel fiber was also added to enhance the tensile capacity of recycled aggregate concrete. The main goal of this study was to investigate the characteristics of concrete using ground granulated blast-furnace slag (GGBS) as a binding material on recycled aggregate fibers reinforced concrete (RAFRC). Mechanical performance was assessed through compressive strength and split tensile strength, while durability aspects were studied through water absorption, acid resistance, and dry shrinkage. The results detected from the different experiments depict that, at an optimum dose (40% RCA, 20%GGBS, and 2.0%), compressive and split tensile strength were 39% and 120% more than the reference concrete, respectively. Furthermore, acid resistance at the optimum dose was 36% more than the reference concrete. Furthermore, decreased water absorption and dry shrinkage cracks were observed with the substitution of GGBS into RAFRC.

scholarly journals Effect of Mineral Admixtures on the Performance of Low-Quality Recycled Aggregate Concrete

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.

scholarly journals Properties of Concrete Using Treated Low-Class Recycled Coarse Aggregate and Blast Furnace Slag Sand

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 843
Author(s):  
Yuji Miyazaki ◽  
Takeshi Watanabe ◽  
Yuji Yamada ◽  
Chikanori Hashimoto
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Hardened Concrete ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Furnace Slag

Since high quality natural aggregates are becoming scarce, it is important that industrial recycled products and by-products are used as aggregates for concrete. In Japan, the use of recycled aggregate (RG) is encouraged. Since, strength and durability of recycled aggregate concrete is lower than that of normal aggregate concrete, the use of recycled aggregate has not been significant. In order to improve physical properties of concrete using recycled coarse aggregate, blast furnace slag sand has been proposed. Recently, blast furnace slag sand is expected to improve durability, freezing, and thawing damage of concrete in Japan. Properties of fresh and hardened concrete bleeding, compressive strength, and resistance to freezing and thawing which are caused by the rapid freezing and thawing test using liquid nitrogen is a high loader than the JIS A 1148 A method that were investigated. As a result, concrete using treated low-class recycled coarse aggregate and 50% or 30% replacement of crushed sand with blast furnace slag sand showed the best results, in terms of bleeding, resistance to freezing and thawing.

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 A Novel Artificial Neural Network to Predict Compressive Strength of Recycled Aggregate Concrete

2021 ◽  
Vol 11 (22) ◽  
pp. 11077
Author(s):  
David Suescum-Morales ◽  
Lorenzo Salas-Morera ◽  
José Ramón Jiménez ◽  
Laura García-Hernández
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Dry Density ◽  
Aggregate Concrete ◽  
Concrete Production ◽  
Artificial Neural

Most regulations only allow the use of the coarse fraction of recycled concrete aggregate (RCA) for the manufacture of new concrete, although the heterogeneity of RCA makes it difficult to predict the compressive strength of concrete, which is an obstacle to the incorporation of RCA in concrete production. The compressive strength of recycled aggregate concrete is closely related to the dosage of its constituents. This article proposes a novel artificial neural network (ANN) model to predict the 28-day compressive strength of recycled aggregate concrete. The ANN used in this work has 11 neurons in the input layer: the mass of cement, fly ash, water, superplasticizer, fine natural aggregate, coarse natural or recycled aggregate, and their properties, such as: sand fineness modulus of sand, water absorption capacity, saturated surface dry density of the coarse aggregate mix and the maximum particle size. Two training methods were used for the ANN combining 15 and 20 hidden layers: Levenberg–Marquardt (LM) and Bayesian Regularization (BR). A database with 177 mixes selected from 15 studies incorporating RCA were selected, with the aim of having an underlying set of data heterogeneous enough to demonstrate the efficiency of the proposed approach, even when data are heterogeneous and noisy, which is the main finding of this work.

scholarly journals Investigation of Properties of Concrete Produced with Recycled Aggregates

2021 ◽  
Vol 1 (2) ◽  
pp. 26-34
Author(s):  
Gökhan KAPLAN
Keyword(s):  
Acid Resistance ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Environmental Damage ◽  
Freezing And Thawing ◽  
Demolition Waste ◽  
Concrete Production ◽  
Strength And Durability

The greatest frequently applied construction substantial in the construction sector is concrete. Natural resources are mostly used in concrete production. While environmental resources are being consumed, concrete environmental pollution increases during urban transformation or reconstruction. In sustainable life, environmental damage caused by construction demolition wastes necessitates the use of recovered aggregate. Recycled aggregate is a term used to depict squashed solid, mortar, blocks or black-top from development trash that is reused in other structure ventures. Reused total is delivered by pounding annihilated waste to recover the total. For as far back as not many decades the accessibility of Construction and demolition waste has expanded so a lot of that the solid business has started using it thusly decreasing the number of totals. The goal is to examine the physical properties, (grain size distribution, density and water absorption) and mechanical properties, (for example, compressive strength, flexural strength, modulus of elasticity and splitting tensile strength) and durability properties, (for example, sulfate resistance, freezing and thawing resistance, acid resistance, high temperature effect and abrasion resistance) of recycled aggregate. It is seen that the mechanical and durability conduct of recycled aggregate concrete is optional to that of standard concrete yet with the utilizing various admixture and unique blending approach, required properties can be accomplished.

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

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.

Durability Studies on High Strength Recycled Aggregate Concrete

2016 ◽  
Vol 708 ◽  
pp. 70-75
Author(s):  
K. Jagannadha Rao ◽  
M.V.S.S. Sastri
Keyword(s):  
Experimental Investigation ◽  
Acid Resistance ◽  
High Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Acidic Environment ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Loss Of Weight ◽  
Durability Performance

The idea of recycling concrete waste as coarse aggregates for new concrete construction is gaining importance on the international scale but the studies on durability performance of Recycled Aggregate Concrete (RAC) are limited. There is a little or no work carried out on high strength recycled aggregate concrete. This study was an attempt to investigate and compare the acid resistance of the RAC and Natural Aggregate Concrete (NAC) of grade M50. In the present experimental investigation, concrete specimens of 0% and 50% RAC were prepared, cured and immersed in H2SO4 solution at 3% concentration at 7 and 28 days respectively. The period of exposure was varied from 3 days to 56 days. The loss of weight, compressive and tensile strengths of the specimens were found to be higher when RAC is exposed to acidic environment compared to NAC.

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