Effect of Aggregate Mineralogy and Concrete Microstructure on Thermal Expansion and Strength Properties of Concrete

Abstract

Aggregate type and mineralogy are critical factors that influence the engineering properties of concrete. Temperature variations result in internal volume changes could potentially cause a network of micro-cracks leading to a reduction in the concrete's compressive strength. The study specifically studied the effect of the type and mineralogy of fine and coarse aggregates in the normal strength concrete properties. As performance measures, the coefficient of thermal expansion (CTE) and compressive strength were tested with concrete specimens containing different types of fine aggregates (manufactured and natural sands) and coarse aggregates (dolomite and granite). Petrographic examinations were then performed to determine the mineralogical characteristics of the aggregate and to examine the aggregate and concrete microstructure. The test results indicate the concrete CTE increases with the silicon (Si) volume content in the aggregate. For the concrete specimens with higher CTE, the micro-crack density in the interfacial transition zone (ITZ) tended to be higher. The width of ITZ in one of the concrete specimens with a high CTE displayed the widest core ITZ (approx. 11 µm) while the concrete specimens with a low CTE showed the narrowest core ITZ (approx. 3.5 µm). This was attributed to early-age thermal cracking. Specimens with higher CTE are more susceptible to thermal stress.

Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates

“…The most important factor determining the water amount needed is the aggregate shape and its surface characteristics-the greater the surface area, the higher the water demand [4,5]. On their part, limestone aggregates have certain characteristics, such as rough surface texture and irregular shape, which favors the increment of adhesion between the cement paste and the aggregates [6]. The chemical interaction between limestone aggregate and cementing matrix produces an increase in the strength bond among them at older ages in the area known as interface zone [7], which is considered the weakest component [8].…”

Aplicação de resíduos na fabricação de concreto: como técnicas analíticas de caracterização podem auxiliar na escolha preliminar do material mais adequado?

“…Outros aspectos que devem ser avaliados para verificar o potencial de aplicabilidade de resíduos como agregados referem-se à mineralogia e morfologia de suas partículas. Isso porque essas propriedades são consideradas fatores críticos que irão influenciar nas características finais do concreto [39]. Por exemplo, AN et al [39] avaliaram o efeito da mineralogia dos agregados sobre as propriedades do concreto.…”

“…Isso porque essas propriedades são consideradas fatores críticos que irão influenciar nas características finais do concreto [39]. Por exemplo, AN et al [39] avaliaram o efeito da mineralogia dos agregados sobre as propriedades do concreto. Dentre outras técnicas utilizadas, os autores utilizaram microscopia eletrônica de varredura (MEV) para avaliação morfológica, e energia dispersiva de raios-X (EDS) para a identificação da composição química dos agregados avaliados no estudo.…”

Research on the Thermal Properties of Fireplace Concrete Materials Containing Various Mineral Aggregates Enriched by Organic and Inorganic Fibers

“…Materials 2021, 14, x FOR PEER REVIEW 2 of 21 causes micro-cracking in the material and weakening of the structure [4]. Interesting results were also obtained by examining the compressive strength and pore distribution in concrete working at above 500 °C [5,6].…”