scholarly journals Scanning Electron Microscopy of Metakaolin Based Geopolymer Concrete

2021 ◽  
Vol 2114 (1) ◽  
pp. 012061
Author(s):  
Layth Al-Jaberi ◽  
Al-Saraj K. Wissam Al-Saraj ◽  
Al-Serai J. Sahar Al-Serai
Keyword(s):  
Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Geopolymer Concrete ◽  
Recycled Concrete Aggregate ◽  
Normal Concrete ◽  
Sem Study ◽  
Concrete Mix ◽  
Scanning Electron

Abstract This work is a Scanning Electron Microscope (SEM) study to investigate the behaviour of Metakaolin based GPC mixes with and without cement and containing recycled concrete aggregate. Three (3) GPC mixes and Normal Concrete mix (NC) designed mingled and tested to achieve the goals of this research. Control specimens were cast from each mix to determine the mechanical properties for each mix. (12) SEM micrographs from carefully selected samples. SEM study confirmed that the presence of recycled concrete aggregate can be a source of generating cracks and fissures. The un-hydrated cement particles in recycled aggregate can contribute to further hydration when contact with water. Also, the metakaolin based GPC matrix with natural aggregate showed enormous with unrealized morphology, which indicates amorphous. Finally, the replacement of 20% of Metakaolin with cement led to enhance mechanical properties.

Research on Mixture Ratio of Recycled Concrete Aggregate in Concrete

2012 ◽  
Vol 193-194 ◽  
pp. 1371-1375
Author(s):  
Yong San Cheng ◽  
Ke Qiang Yu ◽  
Shuang Xi Wang
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Raw Materials ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Mixture Ratio

In order to better understand the recycled concrete aggregate, it is essential to investigate the different mixture ratio in it. For determining the better mixture ratio of recycled concrete aggregate, the experimental investigation was conducted by making use of recycled concrete aggregate of different ratio instead of small stones in concrete, while maintaining the proportion of other raw materials of concrete unchanged. Its mechanical properties were also investigated. It is found that the better materials proportion of recycled concrete is that sand: recycled aggregate: water= 1: 1.8 : 2.1: 0.55.

High Performance Concrete with SCM and Recycled Aggregate

2016 ◽  
Vol 677 ◽  
pp. 233-240 ◽  
Author(s):  
Wojciech Kubissa ◽  
Roman Jaskulski ◽  
Artur Koper ◽  
Marcin Supera
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Waste Materials ◽  
Concrete Aggregate ◽  
Reinforced Concrete Structures ◽  
Recycled Concrete Aggregate ◽  
Class F Fly Ash

In the article the possibility of utilization of two waste materials: Recycled Concrete Aggregate (RCA) fraction 4-16 mm and Class F fly ash (from coal burning power plant) in high perfor-mance concrete (HPC) was presented. Concrete with RCA were made with varying amount of cement and Suplementary Cementing Materials (SCM). The specimens of concrete were tested to compare mechanical properties as well as some properties related to the durability of concrete. Compression strength values up to 71.40 MPa were achieved and good values of properties determinig durability of reinforced concrete structures.

Effect of Water Reducing Admixtures and Construction Variability in Concrete Containing Recycled Aggregate Concrete

2021 ◽  
Vol 47 (3) ◽  
pp. 456-464
Author(s):  
Claude Villiers
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Target Strength ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Effect Of Water ◽  
Concrete Mixtures ◽  
Concrete Mix

The objectives of this project are to evaluate the effect of water reducing admixtures and construction variability in concrete mixtures containing recycled concrete aggregate (RCA). A concrete mix that was approved for curbs and sidewalks in the State of Florida was selected. Based on the analysis conducted, it was found that properties of the RCA were comparable to the virgin aggregate used in this project. However, the absorption of the RCA was double as compared to the limestone. Although the compressive strength of the virgin mix was decreased by 19% when RCA was introduced into the mix, both mixes met the target strength (17.2 MPa). Admixture has a significant impact on all the mixes, especially on mixes that contained RCA. When admixture was omitted, the 28-day compressive strength dropped to nearly 55% on the mixture containing RCA. In addition, the RCA mix without the admixture did not reach the target strength at 28 days. Similarly, construction variability has a significant effect on the compressive strength of the mixes. When the RCA content was increased by 15% and 25% respectively, the concrete paste was weak. These mixtures did not meet the target strength at 28 days.

Mechanical Properties of Concrete Using Treated Recycled Concrete Aggregate in Marine Environment

2020 ◽  
Vol 841 ◽  
pp. 138-143
Author(s):  
Sallehan Ismail ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Marine Environment ◽  
Impact Resistance ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Curing Conditions

This study also investigates the effectiveness of multiple surface modification of recycled concrete aggregate (RCA) with respect to mechanical properties of the resultant recycled aggregate concrete (RAC) when exposed to various curing conditions, namely, normal water (Nw) and seawater (Sw). The properties included compressive and flexural strength and impact resistance. Findings show that effect inclusion of the treated coarse RCA is significant in enhancing the mechanical properties of RAC. The exposure to Sw appears to affect the degradation of the compressive strength of RAC remarkably in a marine environment. In this case, however, using of treated RCA is found beneficial in decreasing the deterioration in the compressive strength of RAC.

scholarly journals Influence of Impregnation of Recycled Concrete Aggregate on the Selected Properties of Concrete

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4611
Author(s):  
Roman Jaskulski ◽  
Pavel Reiterman ◽  
Wojciech Kubissa ◽  
Yaroslav Yakymechko
Keyword(s):  
Mechanical Properties ◽  
Cement Paste ◽  
Water Glass ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Impregnation Method ◽  
Recycled Concrete Aggregate ◽  
Freezing And Thawing ◽  
Durability Properties

The paper focuses on investigating the effect of impregnation of recycled concrete aggregate on the mechanical and durability properties of concrete using this aggregate. Cement paste, limewater and diluted water glass were used to impregnate the aggregate. Both a single impregnation and a double impregnation using two different solutions were carried out. A total of four groups of concrete series, with two values of w/c ratio (0.45 and 0.60), were made. Concrete made using the impregnated aggregate was tested and the results were compared with those of concrete made using untreated recycled aggregate of the same kind. The results indicate that impregnation of aggregate improves the mechanical properties of concrete in many cases but reduces its resistance to cyclic freezing and thawing. Furthermore, in the case of impregnation with two solutions, the order in which the impregnants are applied influences the effect obtained. Using the results received, the impregnation methods were ranked in order from best to worst. The best impregnation method proved to be with cement paste, followed by diluted water glass, while the worst results were obtained with limewater, followed by diluted water glass.

scholarly journals Mechanical properties of roller compacted concrete containing recycled concrete aggregate

2021 ◽  
Vol 20 (2) ◽  
pp. 277-290
Author(s):  
Hojjat Hosseinnezhad ◽  
◽  
Daniel Hatungimana ◽  
Şemsi Yazıcı ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Detrimental Effect ◽  
Impact Resistance ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Limestone Aggregate ◽  
Roller Compacted Concrete

The compressive strength, splitting tensile strength, pulse velocity, and drop weight impact resistance of roller-compacted concrete (RCC) mixtures containing recycled concrete aggregate (RCA) were investigated. The cement contents of the RCC mixtures were chosen as 150, 200 and 250 kg/m3. In addition to the control mixtures containing no RCA, 25, 50, 75, and 100 wt% of the crushed limestone aggregate was replaced with RCA. In this way, 15 RCC mixtures were prepared. The water content of RCC mixtures was determined by the maximum density method. The results showed that increasing the amount of recycled aggregate decreased the mechanical properties of the concrete. However, up to 25% replacement level, recycled aggregate had not a significant detrimental effect on the properties of RCC. Besides, the detrimental effect of RCA substitution was more pronounced in leaner mixtures and reduced by increasing the cement content of the RCC.

Critical Analysis of Recycled Aggregate and Concrete with Recycled Aggregate

2011 ◽  
Vol 99-100 ◽  
pp. 1274-1280
Author(s):  
Neela Deshpande ◽  
S.S Kulkarni
Keyword(s):  
Compressive Strength ◽  
Critical Analysis ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Waste Materials ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Mix

One of the construction sector's major contributions to the preservation of the Environment and sustainable development is the reuse and recycling of the waste materials it generates (reducing, reusing, recycling and regenerating the residues that originate the constructive activity). With this view an experimental program was undertaken which helped in judging the effectiveness of using Recycled aggregate in concrete ,by assessing the properties of Recycled aggregates – Coarse and Fine. Further with the guidance of IS 10262:2009 ,Concrete mix was designed for 28 day compressive strength as 25N/mm2 using conventionally used aggregates and Recycled aggregates. From economy perspective an attempt was made to use superplasticser to reduce cement consumption. With reference to the experimental results, analysis of important properties of both the types of concrete is done and the suitability of use of recycled concrete aggregate for new concrete is judged.

scholarly journals Roller Compacted Concrete with Recycled Concrete Aggregate for Paving Bases

2020 ◽  
Vol 12 (8) ◽  
pp. 3154 ◽  
Author(s):  
Hedelvan Emerson Fardin ◽  
Adriana Goulart dos Santos
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Modulus Of Elasticity ◽  
Splitting Tensile Strength ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Roller Compacted Concrete ◽  
Flexural Tensile Strength ◽  
Mechanical And Physical Properties

This research aimed to investigate the mechanical and physical properties of Roller Compacted Concrete (RCC) used with Recycled Concrete Aggregate (RCA) as a replacement for natural coarse aggregate. The maximum dry density method was adopted to prepare RCC mixtures with 200 kg/m³ of cement content and coarse natural aggregates in the concrete mixture. Four RCC mixtures were produced from different RCA incorporation ratios (0%, 5%, 15%, and 30%). The compaction test, compressive strength, splitting tensile strength, flexural tensile strength, and modulus of elasticity, porosity, density, and water absorption tests were performed to analyze the mechanical and physical properties of the mixtures. One-way Analysis of Variance (ANOVA) was used to identify the influences of RCA on RCC’s mechanical properties. As RCA increased in mixtures, some mechanical properties were observed to decrease, such as modulus of elasticity, but the same was not observed in the splitting tensile strength. All RCCs displayed compressive strength greater than 15.0 MPa at 28 days, splitting tensile strength above 1.9 MPa, flexural tensile strength above 2.9 MPa, and modulus of elasticity above 19.0 GPa. According to Brazilian standards, the RCA added to RCC could be used for base layers.

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