Effect of pozzolans with different physical and chemical characteristics on concrete properties

Abstract

ABSTRACT:The durability of concrete structures is an important issue nowadays. Specifically in the case of reinforced concrete bridges or other infrastructures one of the main form of environmental attack is the penetration of chloride ions, which leads to corrosion of concrete steel reinforcement.This study aims to evaluate the effect of the introduction of metakaolin and diatomite, two chemically and physically different pozzolans, on the resistance of concrete to the penetration of chlorides but also the effect on other properties of concrete, namely, its compressive strength and its porosity distribution.The results of this study show that the pozzolans physical and chemical characteristics have a strong influence on the pozzolans behavior and, consequently, on the concrete properties. RESUMEN: Efecto de puzolanas con características físicas y químicas diferentes sobre las propiedades del hormigón.La durabilidad de las estructuras de hormigón es un tema importante hoy en día. En concreto, en el caso de los puentes de hormigón armado u otras infraestructuras, el principal factor de agresión medioambiental es la penetración de iones cloruro, lo que conduce a la corrosion del acero de refuerzo del hormigón. Este estudio tiene como objetivo evaluar el efecto de la introducción de metacaolín y diatomita, dos puzolanas química y físicamente diferentes, sobre la resistencia del hormigón a la penetración de cloruros, y también sobre otras de sus propiedades como la distribución de su porosidad o su resistencia a compresión.Los resultados de este estudio muestran que las características fisicoquímicas de las puzolanas tienen una fuerte influencia en su comportamiento y en consecuencia, en las propiedades del hormigón.

Combined effect of nano-SiO₂ and nano-Fe₂O₃ on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars

“…The six samples obtained after the flexural strength testing were used for compressive strength testing. Flexural strength values were calculated according to the following equation [1].…”

“…ii) pozzolanic materials were highly sensitive to curing conditions, as they require a longer wet period with a continuous water supply (1). Therefore, 95% of relative humidity curing could be considered insufficient for mortars containing 4-8% of nano-oxides.…”

“…The larger specific surface of new pozzolanic materials (1,2) leads to a higher degree of reactivity (3). In addition, new ultra-high strength concretes have been designed by using fine silica fume and being based on a densified system that contains homogeneously arranged ultra-fine particles.…”

Valorisation of sugarcane bagasse ash (SCBA) with high quartz content as pozzolanic material in Portland cement mixtures

“…The technological advantages of using pozzolanic materials lie in the enhancement of the mechanical properties and durability of blended Portland cement (7)(8)(9). The environmental advantages of using pozzolans extend beyond the reduction of Portland cement consumption, since the most common pozzolanic materials now used are residues from industry (silica fume and fly ash (10)(11)(12)), agroindustry (rice husk ash (13,14)) and others (15). The current study investigates the valorisation of another agroindustry residuesugarcane bagasse ash (SCBA).…”

The influence of curing and aging on chloride transport through ternary blended cement concrete

“…The type of cement, with regard to the incorporation of supplementary cementitious materials (SCM's), has been revealed to be among the factors which have the greatest influence on the resistance of concrete to chloride penetration (7)(8)(9)(10)(11)(12)(13)(14). Blast furnace slag (BFS) is one of the most commonly used SCM's in the manufacture of concretes which are intended for exposure to chloride-contaminated environments, especially marine ones (15), due to its ability to retard the entrance of chloride (16,17).…”