Articles
Amirkabir Journal of Civil Engineering (2588297X)55(3)pp. 723-738
Geopolymer concrete is an innovative building material that is produced by the chemical action of mineral molecules. Removal of cement is one of the great advantages of the use of geopolymer concrete. For this reason, to know the types of geopolymer concrete, it is important to examine its different components and their effect on fracture parameters. In this paper, the fracture parameters of lightweight geopolymer concrete based on class C fly ash (LWFCGC) are presented. In this research, three mix designs with the activator to binder ratios of 0.4, 0.5 and 0.6 were considered. By changing the ratio of activator to glue from 0.6 to 0.4, compressive strength from 18.9 MPa to 28.4 MPa, toughness from 14.07 MPa mm to 19.04 MPa mm 0.5, fracture energy from N/ 17.31 m to 20.98 N/m and the length of the fracture process area changed from 54.12 mm to 29.07 mm.
Abbasi zargaleh, M.R.,
Mazloom, M.,
Jafari samimi, M.,
Ramesht, M.H. Structural Engineering and Mechanics (12254568)94(4)pp. 285-297
Concrete is the most diverse and widely used building material. The production of Portland cement is associated with the production of a large amount of carbon dioxide, which causes air pollution. It is inevitable to find an alternative material for Portland cement. Removal of cement is one of the greatest advantages of using geopolymer concrete. In this article, the results of tests on the fracture parameters of lightweight fly ash C class-based Geopolymer concrete (LWFCGC) as a material that has both advantages of lightness and use of green cement, are presented. These tests include three-point bending test on 49 beams with different activator to binder ratios. Also, compressive strength and tensile strength tests were performed on hardened concrete after 24 hours of processing at 80°C. In these experiments, three mix designs with 0.4, 0.5 and 0.6 activator to binder ratios were considered. By changing the activator to binder ratio from 0.6 to 0.4, compressive strength increased from 18.9 MPa to 28.4 MPa, fracture toughness improved from 19.65 MPa mm0.5 to 23.29 MPa mm0.5, total fracture energy (GF) increased from 59.20 N/m to 65.99 N/m, and the GF/Gf ratio decreased from 3.42 to 3.15. Copyright © 2025 Techno-Press, Ltd.
Materials Letters (18734979)390
Given the abundance, reduced cost, and environmental advantages associated with the utilization of ground granulated blast furnace slag (GGBFS) as a substitute for fly ash, this investigation examines the influence of GGBFS replacement levels of 5, 10, 15, 20, 25, and 30 % on the fracture behavior of lightweight fly ash-based geopolymer concrete (LWFCGC). Concrete specimens were produced using different proportions of GGBFS and fly ash and cured at 80 °C. Subsequently, they were subjected to compressive, tensile, and three-point bending tests. The results indicate that replacing fly ash with GGBFS significantly influences the mechanical properties of geopolymer concrete. Generally, increasing the GGBFS replacement percentage up to 20 % led to higher compressive strength and reduced porosity. However, increasing the GGBFS from 20 % to 30 % led to lower compressive strength. Increasing the replacement percentage from 0 % to 30 % resulted in an increase in fracture toughness from 16.73 to 27.49 MPa√mm and fracture energy from 54.9 to 156.06 N/m. In conclusion, this study shows that GGBFS can be a suitable substitute for fly ash in geopolymer concrete to some extent. By carefully selecting the ratio of GGBFS to fly ash, geopolymer concrete with desirable mechanical properties, fracture parameters, and durability can be achieved. © 2025 Elsevier B.V.
Tangtakabi a., ,
Ramesht, M.H.,
Pahlaviani a.g., A.G.,
Pourrostam t., Iranian Journal Of Science And Technology, Transactions Of Civil Engineering (22286160)48(3)pp. 1245-1260
The corrosion of reinforcement by chloride ions is a significant issue for reinforced concrete (RC) structures, which causes instability and loss of strength of the structure. In this study, the efficacy of various strategies for limiting the effects of chloride-induced corrosion on offshore RC structures was investigated experimentally through a series of experimental tests, including uniaxial compression test, half-cell potential test, and chloride ion penetration test. The tests have been conducted on concrete cube specimens with water/cement (w/c) ratios of 0.38, 0.45, and 0.50, which, for each w/c, the effect of normal cement (control specimens), engineered cementitious composite, self-compacting concrete (SCC), migration corrosion inhibitor (MCI), and microsilica (MS) were separately considered. The compressive strength of the specimens was obtained by uniaxial compression test at 7 and 28 days. Furthermore, to simulate wetting–drying cycles in marine environment, their corresponding 28 days cured specimens were exposed to the marine tidal zone at Technology and Durability Research Centre of Amir Kabir University, located at Bandar-e-Imam Khomeini, Iran, for 16 months and then were tested by half-cell potential and chloride ion penetration tests. The results revealed that, among all the specimens, the specimens with MCI and SCC achieved the highest and lowest compressive strength. In addition, the quantity of chloride ions that penetrate to the specimens indicates a low-risk corrosion for the specimens with MS and MCI and high-risk corrosion for the specimens with SCC. Moreover, it was concluded that using MCI was the most successful strategy for preventing reinforcement corrosion in maritime concrete structures. © The Author(s), under exclusive licence to Shiraz University 2023.