Avaliação de propriedades no estado fresco de argamassas a base de LC³-25 para 3DCP

Abstract

LC³ contemplates a new possibility for a technical and sustainable cement. Due to the abundance of limestone and calcined clay compounds, this cement has been shown to be a promising alternative for replacing the percentage of clinker in cement manufacturing, being able to provide inputs for the growing cement industry while reducing GHG emissions by up to 30%. during the process. In addition, LC³ presents values of plastic viscosity and yield stress compatible with the requirements for 3D printing of concrete (3DCP), a technology that has generated a lot of interest in civil construction. In this study, it is proposed to carry out the characterization of fresh mortars produced for 3DCP based on LC³-25 (with 25% cement), with the purpose of analyzing the behavior of mixtures with a higher cement substitution by calcined clay and limestone, adopting a 2:1 ratio between these materials. Keeping the cement and substituent ratios fixed, the influence of water/cement ratio and the percentage of superplasticizer additive was verified in four previously defined mixtures characterized in terms of slump, slump-flow, density and incorporated air content. An increase in the incorporated air content was observed in mixtures with higher addition of superplasticizer (more viscous). As for slump and slump-flow tests, the mixtures showed higher values 20 minutes after the mixture was prepared, a behavior that may be associated with the thixotropic nature of the compound and which is interesting for 3DCP printing. It was observed that compressive strength after 7 days presents better results in mixtures with a lower water/cement ratio and a higher percentage of superplasticizer. Despite presenting a lower strength result than the reference sample (without cement substitution), the values found are sufficient to apply to 3DCP.