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  • br Introduction Concrete is one of the most

    2020-06-24


    Introduction Concrete is one of the most commonly used materials in the construction industry and its raw material is available throughout the world. Concrete is derived from ordinary Portland cement and is used for the construction and development of infrastructures. Research shows that demand for concrete cement will increase in the future. The cement production will require the consumption of natural resources and release a large amount of carbon dioxide into the environment. It is estimated that 5–7 percentage of total greenhouse gases produced in the world is released through the cement production process. Moreover, the process of cement production consumes the most cAMPS-Rp, triethylammonium salt after steel and aluminium production. One the other hand, normal concrete is degraded under various environmental conditions [1]. Cracking and erosion are factors that influence its safety and the behaviour of concrete during concrete life. It is also found that a lot of structural concretes, particularly those constructed in corrosive environments, begin to degrade after about 20 years [2]. Over the last few years, attention has been paid to environmental issues and the use of environmentally-friendly building materials by many researchers and governments [3], [4]. That is why, the necessity of expanding and conducting research in the production of new and alternative concrete is felt. The existence of a large amount of industrial by-products materials, each of which poses a challenge during disposal, can be beneficial as raw materials for alkali-activated pastes [5], [6], [7]. For instance, the GGBFS which is produced during the process of iron pig manufacture is one of the most widely used materials in the production of AAC. When the slag is combined with a suitable active ingredient, the resulting paste produces good properties for the manufacture of mortar or concrete. The slag that has cooled slowly is crystallized and is not suitable for paste making, but if the slag is cooled by high-pressure water flow, they become slag and become glassy and chemically which can be activate in combination with components paste. Researchers have concluded that GGBFS-based AAC have high mechanical strength in the early stages of curing and are resistant to corrosive environments such as acid. It also has a good resistance to chloride ion penetration and is more resistant to high temperatures. Rice husk ash (RHA) is a highly reactive pozzolan material that is produced by burning rice husk at a specified and controlled temperature, and has been served as a substitute for Portland cement, over the last years [8], [9], [10]. Replacing the fraction of RHA with cement resulted in reduction of concrete porosity, improving the microstructure of the interfacial transitional zone (ITZ) between cement paste and materials, improving resistance to sulphate attack and chloride penetration, as well as lower cost and environmental benefits associated with waste disposal cAMPS-Rp, triethylammonium salt and reduction in carbon dioxide emissions. It has been reported that RHA contains high amounts of non-crystalline form of silica. The reactivity of the RHA depends mainly on the amount of non-crystalline silica (amorphous) and the specific surface of the ash [11]. These factors are related to the operations performed on the husk before burning, as well as to the temperature, duration of burning and geographic location of rice production [12], [13]. Nowadays, RHA is being used in production of low cost and environmental-friendly concretes, high performance and lightweight concretes [14], [15]. Due to the benefits RHA provides, it can be also used to produce alkaline solution with high amounts of silica. In other words, it can be applied in the process of geopolymerization [16], [17], [18]. There are a wide range of studies on alkali-activated paste or concrete which the base substance is FA [19], [20], [21]. In this regard, RHA or GGBFS have been involved in a few studies [22], [23], [24], [25]. Mermerdas et al. reported that the increment in the binder content increases the compressive strength of light-weight geopolymer mortar made of GGBFS [26]. The strength increases with the increase of curing temperature and curing period of geopolymer mortar. Nath and Sarker investigated the impact of GGBFS on setting, workability and early strength properties of fly ash geopolymer concrete cured in ambient condition [27]. It was reported that inclusion of GGBFS with Class F fly ash helped achieve setting time and compressive strength comparable to those of ordinary Portland cement. He et al. evaluated the mechanical properties of alkali-activated pastes made of red mud (RM) and RHA [22]. It was reported that the compressive strength and Young’s modulus strengthen significantly by prolonged curing, however the ductility would be reduced. In another study, Detphan et al. [23] investigated the compressive strength of AAC containing FA and RHA. It was found that based on the ratio of sodium silicate (SS) to sodium hydroxide (SH), the compressive strength could be ranged from 12 to 56 MPa. SS/SH ratio of 4 gave the highest strength compared to the other ratios [23].