Obtained natural sands can present different particle size distributions (PSD), although they have the same mineralogical origin. These differences directly influence the physical and mechanical behavior of mortars and, therefore, the performance of mortar and ceramic renderings. Standardizing the particle size of sands based on pre-established requirements in normative standards (NBR 7214 or ASTM C778) is one way to minimize these effects. However, these standards do not consider the optimization of the granular skeleton through the analysis of bulk density and PSD, which may be insufficient to obtain satisfactory results. Therefore, this paper analyzes the effects of using different particle size ranges on the physical and mechanical behavior of cement and hydrated lime mortars. The properties of consistency index, bulk density, air content, capillary water absorption, water absorption by immersion, flexural strength, compressive strength, and dynamic modulus of elasticity were evaluated. For this purpose, standardized sands of the same mineralogical origin were made with different particle size ranges, being: (i) standardized sand constituted by 25% of coarse and fine fractions (S25-control), (ii) standardized sand constituted by 30% of coarse fraction and 20% of fine fraction (S30-20), and (iii) standardized sand composed by 40% of coarse fraction, and 10% of fine fraction (S40-10), respectively. The results indicated that variations in the particle size composition of the standardized sands are necessary to obtain mixtures with higher compactness and, therefore, mortars with better physical and mechanical performance. Thus, the dosage of the particle size fractions of standardized sand should consider the optimization of the granular skeleton, being the unit mass and the granulometric composition as important parameters to meet this premise.
RESUMO Devido ao alto consumo de areia de rio na construção civil e sua extração abusiva, cujos resultados são a geração de diversos impactos ambientais, este estudo analisa a influência da utilização de areia de praia em substituição à areia proveniente de leito de rio na produção de argamassas de revestimento. A partir da areia de rio, foram confeccionadas outras duas variações: a primeira possuía 70% de fração fina (partículas <1,18 mm) e 30% de fração média (partículas <2,36 mm); e a segunda, 60% de fração fina e 40% de fração média. Foram utilizados cimento Portland (CP II-Z) e cal hidratada (tipo CHI) como aglutinantes em proporção constante (em massa) de 1:3 (aglomerante/agregado), com variações de 1:1:6 e 1:2:9 (cimento, cal e agregado). O programa experimental consistiu na análise dos agregados (por meio da granulometria e da massa unitária) e das argamassas no estado fresco e endurecido. No estado fresco foi determinada a relação entre o consumo de água e a consistência e a densidade de massa aparente. No estado endurecido determinou-se o coeficiente de capilaridade, a taxa de variação de massa e a resistência mecânica à compressão e à tração. Os resultados indicaram que a areia de praia e a de rio apresentam comportamentos físicos semelhantes, embora a primeira possua distribuição granulométrica mais uniforme e maior quantidade de finos, refletindo diretamente no desempenho das argamassas.
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