scholarly journals Modelling and Optimization of the Impact Resistance of Graphene Oxide Modified Crumb Rubber-ECC Using Response Surface Methodology

2021 ◽  
Vol 1197 (1) ◽  
pp. 012043
Author(s):  
Isyaka Abdulkadir ◽  
Bashar S. Mohammed ◽  
M. S. Liew ◽  
M. M. A. Wahab
Keyword(s):  
Response Surface Methodology ◽  
Graphene Oxide ◽  
Response Surface ◽  
Predictive Models ◽  
Impact Resistance ◽  
Crumb Rubber ◽  
Test Method ◽  
Fine Aggregate ◽  
The Impact

Abstract This paper presents the findings of an investigation on the impact resistance of graphene oxide (GO) modified rubberized engineered cementitious composite (GOCRECC) and the development of response-predictive models and optimization using response surface methodology (RSM). The input factors considered as the independent variables were the GO at 0, 0.02, 0.04, 0.06 and 0.08% addition by cement weight and crumb rubber (CR) at 1, 3 and 5% replacement of fine aggregate. Fifteen mixes having different quantities of input factors were used for the determination of the initial (E1) and ultimate (E2) impact energy using the ACI 544. R drop weight impact test method. The results showed that impact resistance of the GOCRECC mixes increased with increasing contents of the input factors. Response predictive models for E1 and E2 were developed and found to have high R2 values of 78 and 93% respectively, after validation using the analysis of variance (ANOVA). The optimization performed yielded an optimal amounts of the input factors of 0.0347 and 5% for GO and CR respectively at a desirability value of 74%.

scholarly journals Acid and Sulphate Attacks on a Rubberized Engineered Cementitious Composite Containing Graphene Oxide

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3125
Author(s):  
Lavaniyah Sabapathy ◽  
Bashar S. Mohammed ◽  
Amin Al-Fakih ◽  
Mubarak Mohammed A Wahab ◽  
M. S. Liew ◽  
...  
Keyword(s):  
Weight Loss ◽  
Response Surface Methodology ◽  
Graphene Oxide ◽  
Response Surface ◽  
Length Change ◽  
Crumb Rubber ◽  
Cementitious Composite ◽  
Acid Attack ◽  
Engineered Cementitious Composite ◽  
Chemical Attack

The objective of this research was to determine the durability of an engineered cementitious composite (ECC) incorporating crumb rubber (CR) and graphene oxide (GO) with respect to resistance to acid and sulphate attacks. To obtain the mix designs used for this study, response surface methodology (RSM) was utilized, which yielded the composition of 13 mixes containing two variables (crumb rubber and graphene oxide). The crumb rubber had a percentage range of 0–10%, whereas the graphene oxide was tested in the range of 0.01–0.05% by volume. Three types of laboratory tests were used in this study, namely a compressive test, an acid attack test to study its durability against an acidic environment, and a sulphate attack test to examine the length change while exposed to a sulphate solution. Response surface methodology helped develop predictive responsive models and multiple objectives that aided in the optimization of results obtained from the experiments. Furthermore, a rubberized engineered cementitious composite incorporating graphene oxide yielded better chemical attack results compared to those of a normal rubberized engineered cementitious composite. In conclusion, nano-graphene in the form of graphene oxide has the ability to enhance the properties and overcome the limitations of crumb rubber incorporated into an engineered cementitious composite. The optimal mix was attained with 10% crumb rubber and 0.01 graphene oxide that achieved 43.6 MPa compressive strength, 29.4% weight loss, and 2.19% expansion. The addition of GO enhances the performance of rubberized ECC, contributing to less weight loss due to the deterioration of acidic media on the ECC. It also contributes to better resistance to changes in the length of the rubberized ECC samples.

Evaluating the impact resistance of roller compacted concrete containing crumb rubber and nanosilica using response surface methodology and Weibull distribution

2019 ◽  
Vol 16 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Musa Adamu ◽  
Bashar S. Mohammed ◽  
Mohd Shahir Liew ◽  
Wesam Salah Alaloul
Keyword(s):  
Weibull Distribution ◽  
Impact Resistance ◽  
Crumb Rubber ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Content Type ◽  
Roller Compacted Concrete ◽  
The Impact ◽  
Two Parameter

Purpose Roller compacted concrete (RCC) pavement is used in areas subjected to heavy impact loads; therefore, higher impact resistance is a desirable property of consideration. This study aims to investigate the effect of partial replacement of fine aggregate with crumb rubber (CR) and the addition of nanosilica (NS) by weight of cementitious materials on the impact resistance of roller compacted rubbercrete (RCR). Design/methodology/approach Four replacement levels of CR (0, 10, 20 and 30 per cent) and four addition levels of NS (0, 1, 2 and 3 per cent) were considered. The impact resistance test was carried out using the drop weight test recommended by ACI 544. Findings The results showed that the impact resistance of RCR increases with an increase in both CR and NS addition, though for CR above 20 per cent, sudden drop in impact resistance was observed. However, NS reduces the ductility of RCR by decreasing the post-cracking impact resistance. Response surface methodology was used to develop models for predicting the impact resistance of RCR, and the developed models showed a high degree of correlation. As a result of wide variations in the impact drop test data, two-parameter Weibull distribution function was used for the data analysis, and it was found that the probabilistic distributions of the first crack and ultimate failure impact resistance follow the two-parameter Weibull distribution function. Originality/value In this work, the effect of partial replacement of fine aggregate with CR and the addition of NS by weight of cementitious materials on the impact resistance of RCC pavement has been investigated. CR has been used to increase the impact resistance of RCC Pavement.

scholarly journals Mechanical Properties of Crumb Rubber Mortar Containing Nano-Silica Using Response Surface Methodology

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5496 ◽  
Author(s):  
Syafiqah Shahrul ◽  
Bashar S. Mohammed ◽  
M. M. A. Wahab ◽  
M. S. Liew
Keyword(s):  
Mechanical Properties ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Impact Resistance ◽  
Crumb Rubber ◽  
Partial Replacement ◽  
Nano Silica ◽  
The Sustainable Development ◽  
Fine Aggregates ◽  
Breeding Grounds

Crumb rubber (CR) from scrap tires is used as a partial replacement of fine aggregates in cement paste. This promotes the sustainable development of the environment, economy, and society, as waste tires are non-biodegradable and flammable. They occupy large landfill areas and are breeding grounds for mosquitoes and rodents. Inclusion of CR in mortar leads to several improvements on the mixture properties such as ductility, toughness, and impact resistance. However, it exhibits lower strengths and Modulus of Elasticity (ME). Therefore, to promote the use of mortar containing CR, it is vital to improve its mechanical strength. Past studies proved that nano-silica (NS) improves the strength of concrete due to the physico-chemical effects of NS. This study aims to examine the mechanical properties of crumb rubber mortar containing nano-silica (NS-CRM) and to develop models to predict these properties using Response Surface Methodology (RSM). Two variables were considered, CR as partial replacement to sand by volume (0%, 7.5%, 15%), and NS as partial replacement to cement by weight (0%, 2.5%, 5%). The results demonstrated a significant improvement in the mechanical properties of CRM when incorporating NS, and the models developed using RSM were acceptable with a 2% to 3% variation.

scholarly journals RP-HPLC Method for Determination of Salbutamol and Bromhexine in Syrup: Modelling and Optimization by Response Surface Methodology

2020 ◽  
Vol 32 (12) ◽  
pp. 3135-3143
Author(s):  
Chung Duong Dinh ◽  
Yen Nguyen Ngoc Thi ◽  
Khanh Quan Nguyen Huu ◽  
Duy Chinh Nguyen ◽  
Ung Thanh Dat ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Flow Rate ◽  
Mobile Phase ◽  
Hplc Method ◽  
Mobile Phase Flow Rate ◽  
Rp Hplc ◽  
Limit Of Quantitation ◽  
The Impact

In present work, the RP-HPLC method was established for the determination of bromhexine and salbutamol in syrup by using a design of experiment approach. The Plackett-Burman design was applied to screen the influence of independent variables (ratio of organic solvent and pH in mobile phase, flow rate, column temperature, sample injection volume and detection wavelength) on the output data of chromatographic signals (peak area, tailing factor, theoretical plates, resolution) of bromhexine and salbutamol. The Pareto diagram shows that the selected variables affect mainly target function. A central composite design has been used to optimize the values of main factors and Design expert® software predicts the interaction and quadratic model to evaluate the impact of input parameters on output. The optimal conditions were determined with the support of response surface methodology for flow rate 0.9 mL/min, temperature 25 °C and 60% methanol in water with 0.06% orthophosphoric acid as the mobile phase. Good linearity was observed in the concentration range of 8-48 μg/mL for bromhexine and 4-24 μg/mL for salbutamol with a significantly high correlation coefficient (R > 0.999). The limit of detection and limit of quantitation were 0.32 and 0.96 μg/mL, respectively for bromhexine and 0.08 and 0.25 μg/mL, respectively for salbutamol. This method was validated according to ICH guidelines.

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