Argamassa autonivelante para contrapiso: efeito do tipo de cimento no comportamento físico-mecânico

Abstract

Self-leveling mortar (SLM) is inserted in the construction market as an innovative product due to its special properties when compared to conventional mortars due to the filling of empty spaces and self-compacting only under the effect of gravity, the ability to flow and level without the occurrence of segregation. The use of CP V – ARI cement is common for its production, since its high fineness favors the fluidity of the material and for providing fast hardening, fundamental characteristics that must be considered in self-leveling mortars (SLM’s). However, the rare availability of this type of cement becomes a limiting factor for its applicability in the region. Therefore, the objective of this research is to develop the study of SLM dosage for screed, adapting it to local materials that favor its design and evaluating its influence on rheological and mechanical characteristics. For the production of these mortars, we used the adaptation by Lopes et al. (2018) of Tutikian's methodology (2004) for self-compacting concrete (CAA), using fines in partial replacement of cement, adopting as controllable factors the type of cement (CP I, CP II-E, CP IV and CP V-ARI) and the type of mineral addition (silica fume and metakaolin). For the characterization of SLM in the fresh state, the mini slump, mini V-funnel, flow retention, mass density and incorporated air content, determination of exudation and healing time tests were performed. In the hardened state, the mechanical resistance to compression and traction in flexion and the retraction of these materials were verified, since it is one of the main pathologies of SLM. Analyzing the results obtained, it was observed that the surface area of the tested cements was the factor that most influenced the performance of the produced mortars, where cements with larger surface areas needed more additive to achieve fresh properties and had the highest rates of retraction. Mineral additions contributed to the cohesion of mortars and reduced shrinkage in mixtures with contents of up to 25% metakaolin and 15% silica fume.