Avaliação da trabalhabilidade e resistência à compressão de pastas cimentícias álcali-ativadas com uso de aditivos tensoativos

Abstract

Portland cement is the most used binder material in the production of mortars and concretes. However, its use is associated with high rates of CO2 released along its production chain, extraction of non-renewable raw materials and generation of solid waste. In view of this, the academy has advanced in studies on materials aimed at a partial or complete replacement of this bindes. Among them, alkali-activated cements have been shown to be an important alternative to mitigate the negative effects of the cement industry. Therefore, the presente study focuses on an evaluation of the workability of alkali-activated cementitious pastes using surface-active additives. The pastes were produced from the mixture of precursors composed of Fly Ash and Basic Oxygen Furnace steel slag interacting with alkaline activators composed

of a mixture of sodium hydroxide and sodium silicate. The composition of the paste is pre- defined and indicated throughout the work, varying the dosage of the surfactant addtives used

for na analysis of its influence on the properties of the paste, such as workability, setting time and compressive strength. The research carried out fits as an explanatory, quantitative and experimental research. The experimental approach adopted was based on the determination of the mechanical properties and the fresh state. Through the test carried out, it was possible to observe that the superplasticizer additive based on polycarboxylate improved the workability of the pastes. The plasticizes additive based on sulfonated salts also showed an increase in the spreading diameter. Regarding the setting time, the surfactant additives allowed a reduction in the final setting time of the paste, acting as setting accelerators under the conditions studied. The surfactant additives also had a negative influence on the compressive strength of the pastes, since there was a decrease in the index in the pastes that contained additive in their composition.