Cura interna de compósitos cimentícios ecoeficientes com areia de cinza de bagaço de cana-de-açúcar por meio de polímeros superabsorventes

Abstract

The high generation of agro-industrial waste, such as Sugarcane Bagasse Ash Sand (SBAS), has aroused notable interest in civil construction, mainly in the search for eco-efficient solutions that can mitigate problems associated with the excessive exploitation of natural resources, as sand. However, due to the refinement of the microstructure of cementitious composites provided by SBAS, it is important to evaluate the shrinkage behavior of these matrices, since this process tends to be more pronounced in denser cementitious matrices. Thus, this study evaluated plastic, autogenous, and drying shrinkage, as well as the physical-mechanical properties of mortars containing 30% SBAS replacing fine aggregate with three types of Superabsorbent Polymers (SAPs), materials explored as agents of internal curing, and two types of cement (CP V ARI and CP III). The most significant results in the presence of only SBAS, without polymers, were the reduction of 18.10% (CP V ARI) and 18.48% (CP III) of autogenous shrinkage. The SAP that promoted the greatest reduction in the average crack thickness indicated a decrease of 81.92% and 39.88%, with the CP V ARI and CP III cement, respectively, in the plastic shrinkage test. Additionally, the effectiveness of SAPs as internal curing agents was observed, especially in the presence of CP III cement, reducing autogenous shrinkage by up to 119.19%. About drying shrinkage, only the SAP with the lowest absorption capacity indicated a significant reduction (24.78%), with CP III cement. No negative influence of SAPs was detected in the flexural strength test. However, SAP with intermediate absorption capacity provided a reduction of 19% (CP V ARI) and 28.55% (CP III) in compressive strength. Therefore, the use of SBAS in with SAPs can bring considerable benefits to mortars, especially in the reduction of cracks arising, mainly, from plastic and autogenous shrinkage.