Stochastic Development Model for Compressive Strength of Fly Ash High-Strength Concrete

Author(s):  
Jian Gong ◽  
Yuanfeng Wang
2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.


Author(s):  
Jamshed Alam

An experimental analysis was conducted to study the effects of using copper slag as a fine aggregate (FA) and the effect of fly ash as partial replacement of cement on the properties high strength concrete. In this analysis total ten concrete mixtures were prepared, out of which five mixes containing different proportions of copper slag ranging from 0% (for the control mix) to 75% were prepared and remaining five mixes containing fly ash as partial replacement of cement ranging from 6% to 30% (all mixes contains 50% copper slag as sand replacements). Concrete matrix were tested for compressive strength, tensile strength and flexural strength tests. Addition of copper slag as sand replacement up to 50% yielded comparable strength with that of the control matrix. However, further additions of copper slag, caused reduction in strength due to an increment of the free water content in the mix. Concrete mix with 75% copper slag replacement gave the lowest compressive strength value of approximately 80 MPa at 28 days curing period, which is almost 4% more than the strength of the control mix. For this concrete containing 50% copper slag, fly ash is introduced in the concrete to achieve the better compressive, split and flexural strengths. It was also observed that, introduction of the fly ash gave better results than concrete containing 50% copper slag. When concrete prepared with 18 % of fly ash, the strength has increased approximately 4%, and strength decreased with further replacements of the cement with fly ash. Hence, it is suggested that 50% of copper slag can be used as replacement of sand and 18% fly ash can be used as replacement of cement in order to obtain high strength concrete.


2018 ◽  
Vol 20 (2) ◽  
pp. 65-70
Author(s):  
Endah Kanti Pangestuti ◽  
Sri Handayani ◽  
Mego Purnomo ◽  
Desi Christine Silitonga ◽  
M. Hilmy Fathoni

Abstract. The use of coal waste (Fly Ash) is currently being developed in building materials technology, as a high-strength concrete mix material. This study aims to determine the strength of concrete by adding fly ash as a substitute for cement in high-strength concrete mixtures. This research was conducted with an experimental method to obtain results and data that would confirm the variables studied. The total number of specimens used in this study were 36 pieces with different sizes of cube tests which were 15 cm x 15 cm x 15 cm. A total of 36 concrete samples were used to test the compressive strength of concrete with a percentage of Fly Ash in  0% (normal concrete), 20%, 25% and 30% with a concrete treatment age of 7 days, 21 days and 28 days. A total of 12 more samples were used to test water absorption in concrete at 28 days of maintenance. Each percentage percentage of Fly Ash uses 3 concrete test samples. The increase in compressive strength occurs at 7, 21 and 28 days in concrete. However, the compressive strength of concrete produced by concrete using the percentage of Fly Ash is always lower than the value of normal concrete compressive strength. From testing the compressive strength of concrete at 28 days of treatment with content of 0%, 20%, 25% and 30% Fly Ash obtained results of 45.87 MPa, 42.67 MPa, 40.89 MPa, and 35.27 MPa respectively


Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 532 ◽  
Author(s):  
Jianwei Zhou ◽  
Dong Lu ◽  
Yuxuan Yang ◽  
Yue Gong ◽  
Xudong Ma ◽  
...  

This paper presents the experimental findings of a study on the influence of combining usage of supplementary cementitious materials (SCMs) on the performance of high-strength concrete (HSC) subjected to elevated temperatures. In this study, four types of HSC formulations were prepared: HSC made from cement and fly ash (FA), HSC made from cement and ultra-fine fly ash (UFFA), HSC made from cement and UFFA-metakaolin (MK), and HSC made from cement and FA-UFFA-MK. Mechanical and physical properties of HSC subjected to high temperatures (400, 600, 800, and 1000 °C) were studied. Furthermore, the relation between residual compressive strength and physical properties (loss mass, water absorption, and porosity) of HSC was developed. Results showed that the combined usage of SCMs had limited influence on the early-age strength of HSC, while the 28-d strength had been significantly affected. At 1000 °C, the residual compressive strength retained 18.7 MPa and 23.9 MPa for concretes containing 30% UFFA-5% MK and 10% FA-20% UFFA-5% MK, respectively. The specimen containing FA-UFFA-MK showed the best physical properties when the temperature raised above 600 °C. Combined usage of SCMs (10% FA-20% UFFA-5% MK) showed the lowest mass loss (9.2%), water absorption (10.9%) and porosity (28.6%) at 1000 °C. There was a strongly correlated relation between residual strength and physical properties of HSC exposed to elevated temperatures.


2013 ◽  
Vol 357-360 ◽  
pp. 1455-1458
Author(s):  
Xiang Jun Dong ◽  
Xin Liu ◽  
Rui Jiang

This paper focuses on experimental investigation to produce high strength concrete by employing twin admixture technique of grade II fly ash and S95 GGBS. Different regions have different characteristic of the material, so the strength of high strength concrete would be influenced. At present most of the domestic studies about high strength concrete use the first class powered coal ash and rarely grade II fly. In this study, grade II fly ash is chosen. The dosage of grade II fly ash, S95 GGBS and the water reducing agent are given as the influencing factors of high-strength concretes compressive strength and collapsed slump, and determined the optimum mix amount of the components. The data of strength about the age of 3 day, 7 day and 28 day are analyzed. The results are showed the optimum content of grade II fly ash is between 15% and 20%, S95 GGBS is 15% and water reducing agent is 2%.


2017 ◽  
Vol 748 ◽  
pp. 301-310 ◽  
Author(s):  
Wei Liu ◽  
Hong Lin Tan ◽  
Cheng Lin Ni ◽  
Zhi Bin Chen ◽  
Tian Zong Luo ◽  
...  

This issue mainly studied the compressive strength and weight loss of high strength concrete in sulfuric and acetic acid attack. Different substitution amounts of silica fume and fly ash single single incorporated and co-incorporated in cement to form high strength concrete. Then weight losses, XRD and SEM were carried out to investigate compressive strength and acid resistance corrosion mechanism after leaching in 5% H2SO4 and 5% CH3COOH solution for 28 days. The results show S10F12 improves the compressive strength by 29.6%, 40.5% and 28.4% in 7, 28 and 56 days curing respectively compared to OPC. The improvement of resistant to 5% H2SO4 and 5% CH3COOH of S10F12 is 38.3% and 112.5% for 28 days immersion respectively, and S10f12 still has compressive strength of 58.8 MP and 45.9 MPa under 5% H2SO4 and 5% CH3COOH attack while OPC only has 38.8MPa and 21.6 MPa after 28 days immersion.


Author(s):  
Temesgen Fantu ◽  
Getasew Alemayehu ◽  
Getachew Kebede ◽  
Yeshi Abebe ◽  
Senthil Kumaran Selvaraj ◽  
...  

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah

2011 ◽  
Vol 121-126 ◽  
pp. 126-131 ◽  
Author(s):  
Qing Lei Xu ◽  
Tao Meng ◽  
Miao Zhou Huang

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.


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