Analysis of Rheological Characteristic Studies of Fly-Ash-Based Geopolymer Concrete

Concrete is a versatile construction material used along with a reinforcement. Concrete is made up of binder materials and aggregates. Cement is a primary binder material used to produce conventional concrete. Carbon dioxide emissions in the atmosphere are a symptom of the issue related to Portland cement manufacture. It is estimated that one ton of cement produced releases an equal amount CO2 into atmosphere. On other hand, many industrial wastes are dumped in open spaces, leading to land pollution. Researchers have developed a construction material known as geopolymer concrete that uses industrial waste materials as a binder material to address these two issues. Excellent mechanical and durability characteristics are displayed by geopolymer concrete. For the creation of geopolymer concrete, fly ash is employed as a binder material. The drawback of utilizing fly ash is the curing method. Due to increased setting time, concrete samples require either heat curing or oven-curing. Geopolymer paste preparation is based on the type of binder materials used. In this study, GGBS is partially added with fly ash to cure specimens in ambient temperature due to presence of a higher amount calcium in GGBS. The present study investigates the consistency of geopolymer pastes, their workability, and the compressive strength of cement mortars by varying the amount of binder content (360 kg/m³ & 400 kg/m³). The molarity of NaOH was varied from 8 to 12. The ratio between binder material and alkaline to binder ratio were 0.45 and 0.50, respectively. The specimens were cured in both ambient and oven temperatures to study their strength development caused by temperature. A total of 396 specimens were cast to study the behavior of geopolymer concrete made with fly ash and GGBS (FAG). The test results revealed that the substitution of 50% GGBS with fly ash exhibited better strength properties during curing. Additionally, by increasing the binder content to 400 kg/m³, the results of 80% GGBS and 20% fly ash revealed excellent consistency among all other mixes. The oven-cured specimens showed more strength compared to specimens cured in ambient temperature, but the ambient cured specimens (ACS) attained the required strength. It was also not practically possible to cure the structural members by oven-curing in the field. The mix with 80% of GGBS and 20% fly ash can be used for construction. The required strength can also be achieved by increasing the molarity ratio.

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