No abstract

Alternative cementitious materials can potentially reduce the environmental impact of the extraction of lime and the hazardous production of Portland cement. Red ceramic waste can be comminuted to fine particles with both filler and pozzolanic activity and used in Portland and lime mortars. This study presents the evaluation of the pozzolanic activity of red ceramic waste by physicochemical and mechanical methods using Portland cement and lime mortars. The evaluated waste depicted high pozzolanic activity and absence of Na2O, and consumed 32% of CaO according to the adapted Chapelle test. The compressive strength recorded in the pozzolanic activity test with lime was 7.1 MPa at 7 days. Moreover, the compressive strength of mixes with 25% replacement of Portland cement by red ceramic waste was 11% higher than the reference waste-free composition. The red ceramic waste depicted adequate characteristics to be used in the production of large volumes of Portland and lime mixes commonly employed in the civil construction.

Avaliação das propriedades físicas, químicas e mineralógicas da fraçãofina (<150 µm) do agregado reciclado de RCD (Evaluation of the physical, chemical and mineralogical properties of the fine fraction (<150 µm) of the recycled CDW aggregate) ResumoFatores como o alto consumo de recursos naturais e os elevados volumes de resíduos produzidos pela indústria da construção civil alertam sobre a importância de reutilizar e reciclar os materiais. Assim, este trabalho objetivou determinar e avaliar as características físicas, químicas e mineralógicas dos finos do agregado reciclado (FAR), comparando-os com finos dos agregados naturais (FAN). Para tanto, determinaram-se a distribuição granulométrica, área específica, formato e textura superficial, índice de atividade pozolânica, óxidos presentes, teor de argamassa aderida e fases minerais. Os resultados mostraram que os FAR apresentam características que se destacam em relação aos FAN, dentre elas o formato mais irregular e superfície porosa. Entretanto, os FAR possuem melhor distribuição granulométrica, o que pode favorecer a compacidade das misturas. Em termos de desempenho pozolânico, os FAR não podem ser considerados como materiais pozolânicos, embora se faça necessário avaliá-los em finura requerida por norma. Palavras-chave: reciclagem, atividade pozolânica, construção civil, fração fina do agregado reciclado. AbstractFactors such as high consumption of natural resources and high volumes of waste produced by the construction industry warn the importance of reusing and recycling materials. Thus, this work aimed to determine and evaluate the physical, chemical and mineralogical characteristics of the fines of recycled aggregate (FRA), comparing them with fine natural aggregates (FNA). For that, particle size, specific area, shape and surface texture, pozzolanic activity index, oxides present, content of adhered mortar and mineral phases were determined. The results showed that the FRA have characteristics that stand out in relation to the FNA, among them the more irregular shape and porous surface. However, the FRA has a better particle size distribution, which may favor the compactness of the blends. In terms of pozzolanic performance, the FRA can not be considered as pozzolanic material, although it is necessary to evaluate them in the fineness required by standard.

This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.