coarse aggregate
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Author(s):  
Barkha Verma

Abstract: Aggregates provide volume at low cost, comprising 66% to 78% of the concrete. With increasing concern over the excessive exploitation of natural and quality aggregates, the aggregate produced from industrial wastes and agricultural wastes is the viable new source for building material. This study was carried out to determine the possibilities of using coconut shells as aggregate in concrete. Utilizing coconut shells as aggregate in concrete production not only solves the problem of disposing of this solid waste but also helps conserve natural resources. In this paper, the physical properties of crushed coconut shell aggregate were presented. The fresh concrete properties such as the density and slump and 28 days compressive strength of lightweight concrete made with coconut shell as coarse aggregate were also presented. The findings indicate that water absorption of the coconut shell aggregate was high about 24% but crushing value and impact value were comparable to that of other lightweight aggregates. The average fresh concrete density and 28days cube compressive strength of the concrete using coconut shell aggregate 1975kg/m3 and 19.1 N/mm2 respectively. It is concluded that crushed coconut shell is suitable when it is used as a substitute for conventional aggregates in lightweight concrete production. Keywords: Coarse Aggregate, Cement, Concrete, Fly Ash, Coconut shell Aggregate, Water, Compressive Strength, Workability, Fine Aggregate.


Author(s):  
Vidhi Sharma

Abstract: This research paper represents the experimental study on use of ceramic waste material as an aggregate in concrete. To reach the goal of sustainable development utilization of waste materials in concrete production is very much useful. The ceramic aggregate used in this study was recycled from industrial ceramic tile waste in India. From the results it can be seen that it is possible to produce a concrete with good strength by using ceramic waste as an aggregate in .It is also seen from the results that the compressive strength characteristics of ceramic aggregate concrete met the required criteria set by various international standards and codes, which shows the ability of ceramic waste to be used as a substitute to the conventional aggregates in concrete. We replaced the coarse aggregate in concrete by 100% to thewaste ceramic aggregate of size 10mm. The water cementratio taken was 0.30 for concrete production and compared it with normal aggregate concrete of M20 grade. By the decrease in water/cement ratio, high strength concrete canbe obtained. But it is found that the workability will be very low. In our project the required workability was achieved by the use of maximum water-cement ratio .To overcome this use of several admixtures like super-plasticizers and silica fume are recommended to add in the mixing so that the workability can be improved. Keywords: Sustainable development, Ceramic waste as aggregate


Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 647
Author(s):  
Meijun Shang ◽  
Hejun Li ◽  
Ayaz Ahmad ◽  
Waqas Ahmad ◽  
Krzysztof Adam Ostrowski ◽  
...  

Environment-friendly concrete is gaining popularity these days because it consumes less energy and causes less damage to the environment. Rapid increases in the population and demand for construction throughout the world lead to a significant deterioration or reduction in natural resources. Meanwhile, construction waste continues to grow at a high rate as older buildings are destroyed and demolished. As a result, the use of recycled materials may contribute to improving the quality of life and preventing environmental damage. Additionally, the application of recycled coarse aggregate (RCA) in concrete is essential for minimizing environmental issues. The compressive strength (CS) and splitting tensile strength (STS) of concrete containing RCA are predicted in this article using decision tree (DT) and AdaBoost machine learning (ML) techniques. A total of 344 data points with nine input variables (water, cement, fine aggregate, natural coarse aggregate, RCA, superplasticizers, water absorption of RCA and maximum size of RCA, density of RCA) were used to run the models. The data was validated using k-fold cross-validation and the coefficient correlation coefficient (R2), mean square error (MSE), mean absolute error (MAE), and root mean square error values (RMSE). However, the model’s performance was assessed using statistical checks. Additionally, sensitivity analysis was used to determine the impact of each variable on the forecasting of mechanical properties.


2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Songfang Xie ◽  
Mingxing Gao ◽  
Hangtian Li

In order to improve mechanical properties of fly ash/slag concrete with large size cobble as coarse aggregate, this paper analyzes the effect of different factors on the concrete through the flexural strength test. The Monte Carlo simulation is used in the finite element solver of ANSYS to conduct the four-point bending beam test. Three-dimensional and two-dimensional finite element models are established to discuss how the gradation of large size cobbles affects the performance of the concrete by comparing macromechanical experiments. Results show that the gradation of large size cobbles is the main factor affecting the performance of the concrete. Slag generates the least effect on the concrete with cobble as coarse aggregate. When the mixing amount of slag and fly ash is 10%, the concrete presents the best flexural performance. Through the numerical loading test of the two-dimensional model for fly ash/slag concrete with cobble as coarse aggregate, it can be concluded that the change of the concrete follows the law of macromechanical properties.


2022 ◽  
Vol 12 (2) ◽  
pp. 857
Author(s):  
Jiaqi Chen ◽  
Xingzao Chen ◽  
Hancheng Dan ◽  
Lanchun Zhang

Pavement temperature field affects pavement service life and the thermal environment the near road surface; thus, is important for sustainable pavement design. This paper developed a combined prediction method for the thermal conductivity of asphalt concrete based on meso-structure and renormalization technology, which is critical for determining the pavement temperature field. The accuracy of the combined prediction method was verified by laboratory experiments. Using the tested and proven model, the effect of coarse aggregate type, shape, content, spatial orientation, air void of asphalt concrete, and steel fiber on the effective thermal conductivity was analyzed. The analysis results show that the orientation angle and aspect ratio of the aggregate have a combined effect on thermal conductivity. In general, when the aggregate orientation is parallel with the heat conduction direction, the effective thermal conductivity of asphalt concrete in that direction tends to be greater. The effective thermal conductivity of asphalt concrete decreases with the decrease of coarse aggregate content or steel fiber content or with the increase of porosity, and it increases with the increase of the effective thermal conductivity of coarse aggregate.


Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 430
Author(s):  
Jawad Ahmad ◽  
Rebeca Martínez-García ◽  
Jesús de-Prado-Gil ◽  
Kashif Irshad ◽  
Mohammed A. El-Shorbagy ◽  
...  

The current practice of concrete is thought to be unsuitable because it consumes large amounts of cement, sand, and aggregate, which causes depletion of natural resources. In this study, a step towards sustainable concrete was made by utilizing recycled concrete aggregate (RCA) as a coarse aggregate. However, researchers show that RCA causes a decrease in the performance of concrete due to porous nature. In this study, waste glass (WG) was used as a filler material that filled the voids between RCA to offset its negative impact on concrete performance. The substitution ratio of WG was 10, 20, or 30% by weight of cement, and RCA was 20, 40, and 60% by weight of coarse aggregate. The slump cone test was used to assess the fresh property, while compressive, split tensile, and punching strength were used to assess the mechanical performance. Test results indicated that the workability of concrete decreased with substitution of WG and RCA while mechanical performance improved up to a certain limit and then decreased due to lack of workability. Furthermore, a statical tool response surface methodology was used to predict various strength properties and optimization of RCA and WG.


2022 ◽  
Vol 12 (1) ◽  
pp. 524
Author(s):  
Chao-Wei Tang ◽  
Chiu-Kuei Cheng ◽  
Lee-Woen Ean

The main purpose of this study was to investigate the mix design and performance of fiber-reinforced pervious concrete using lightweight coarse aggregates instead of ordinary coarse aggregates. There were two main stages in the relevant testing work. First, the properties of the matrix were tested with a rheological test and then different amounts of lightweight coarse aggregate and fine aggregate were added to the matrix to measure the properties of the obtained lightweight pervious concrete (LPC). In order to greatly reduce the experimental workload, the Taguchi experimental design method was adopted. An orthogonal array L9(34) was used, which was composed of four controllable three-level factors. There were four test parameters in this study, which were the lightweight coarse aggregate size, ordinary fine aggregate content, matrix type, and aggregate/binder ratio. The research results confirmed that the use of suitable materials and the optimal mix proportions were the key factors for improving the mechanical properties of the LPC. Due to the use of silica fume, ultrafine silica powder, and polypropylene fibers, the 28-day compressive strength, 28-day flexural strength, and 28-day split tensile strength of the LPC specimens prepared in this study were 4.80–7.78, 1.19–1.86, and 0.78–1.11 MPa, respectively. On the whole, the mechanical properties of the prepared LPC specimens were better than those of the LPC with general composition.


2022 ◽  
Vol 58 (4) ◽  
pp. 158-170
Author(s):  
Kiruthika Chandrasekaran ◽  
Lavanya Prabha Srinivasan ◽  
Neelamegam Meyappan

Resin Concrete uses polymeric resin to replace cement concrete. Four types of polyester resins were identified with Methyl methacrylate as catalyst, calcium carbonate and fly ash as fillers along with river sand and coarse aggregate size of 10mm, 6mm were used to produce resin concrete. Seventy-two trial batches were carried out for preliminary investigation targeting compressive strength of more than 80 MPa (11.6 ksi) and four batches were shortlisted. These four batches along with the addition of glass fiber were taken for detailed investigation of stress strain behavior, young�s modulus, Poisson ratio, various correlative equations among their mechanical properties and durability properties. Developed mix can be recommended for manufacturing various polymer products.


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