With the increasing use of recycled materials from civil construction, mainly as substitute for some aggregates in concrete mixtures, it is necessary to obtain technical information on the performance of these new mixtures. National and international research on the use of ceramic waste in concrete production highlight good results of this new material’s mechanical performance in environmental situations. However, little is known about its behavior at high temperatures. In this context, we sought to verify the performance of concrete mixtures produced with aggregates from ceramic block waste at high temperatures, with evaluation of their residual mechanical strength, axial compressive strength and elastic modulus, and also their tendency to spalling in fire situations. The RILEM-129 MHT method [1] was used for the assessment of residual mechanical strength, and the tendency to spalling was evaluated according to the procedure suggested by Souza and Moreno [2]. In both these evaluations, there is no national standard, and, in the case of spalling, not even an international standard. Three concrete mixtures were used, one prepared with natural coarse basalt aggregate (reference) and the other two by replacing part of this natural aggregate with aggregate from ceramic block waste (40% and 100% of substitution in volume). In the end, it is concluded that the substitution of natural coarse aggregate for lightweight aggregate from ceramic block waste can be an excellent alternative to increase the resistance of concrete to fire. Thus, the results of mechanical strength and spalling in a fire situation, unprecedented in our country, can greatly support the decision-making about the use of this alternative material in the national construction industry.

Mortars are among the most used materials in civil construction, and their mechanical properties are directly related to several parameters, namely structural behavior, durability, and failure mechanisms. As a result, predicting these parameters is essential for preventive and corrective diagnosis of structures composed of this material. Recently, machine learning models have been applied to improve these predictions. Until recently, such predictions were based on traditional empirical procedures, which are unable to capture the variability of material parameters. Nevertheless, as this is still an emerging research topic, many limitations and gaps remain to be investigated, such as the dependence on data structure and the appropriate selection of hyperparameters. Furthermore, most studies applying machine learning to mortars focus on additions, admixtures, or durability- and performance-related aspects, rather than on assessing the efficiency and robustness of the models themselves. In this context, this systematic and critical review aims to identify how machine learning models have been applied to predict the mechanical properties of different mortars. The main input parameters used for this prediction are discussed, and the hyperparameters of several machine learning models are critically analyzed and discussed. The results indicate that tree-based ensemble models perform better than other approaches, with XGBoost showing superior predictive performance.

RESUMO O emprego de resíduo cerâmico na produção do concreto pode ser considerado uma ação viável em prol da sustentabilidade na indústria da construção civil. No entanto, faz-se necessário, o estudo das propriedades físicas e mecânicas do concreto produzido com este resíduo, garantindo segurança e necessária vida útil das edificações. Neste sentido, este trabalho avalia a durabilidade dos concretos produzidos com agregados provenientes de resíduos de cerâmica vermelha visando seu emprego na produção de elementos estruturais em concreto armado. Para tanto, foram produzidos traços com substituição do agregado graúdo natural pelo resíduo de cerâmica vermelha nos teores de 40 e 100% de substituição, em volume. Foram realizadas análises de carbonatação, absorção por permeabilidade capilar, permeabilidade ao ar e penetração por cloretos para verificação da durabilidade, bem como a verificação de suas propriedades mecânicas, em especial, resistência à compressão axial. Os resultados demonstraram menor permeabilidade para os concretos produzidos com resíduo cerâmico e, consequentemente, menor ataque por cloretos e carbonatação para misturas com até 40% de resíduo cerâmico, o que sugere, consequentemente, que elementos estruturais executados com estas misturas alternativas estariam menos propensos à corrosão das armaduras. A análise por microscopia eletrônica por varredura evidenciou uma redução no diâmetro dos poros capilares, resultado da melhor hidratação da fase cimentícia por meio do fenômeno conhecido por cura interna, proporcionado pelo emprego do agregado cerâmico reduzindo, também, a espessura da zona de transição interfacial entre o agregado e a matriz cimentícia.