Abstract
Nanotechnology can significantly improve the mechanical strength and durability of concrete. At the nanoscale, good dispersion of constituent materials is an essential factor for the improvement of concrete properties. In this scenario, the objective of this research was to evaluate the mechanical properties of high performance concrete containing stabilized nano-silica. The incorporation of nano-silica to the polycarboxylate chemical admixture allowed its application in concrete, since the nano-silica was evenly dispersed in the concrete mass. For this study, three different concretes were employed: a reference concrete, one containing stabilized nano-silica and another containing a mixture of silica fume and stabilized nanosilica. The evaluated concrete mechanical properties were the axial compressive strength and secant modulus of elasticity measured in three different ages. The results indicated a substantial increase in concrete compressive strength and modulus of elasticity with the addition of stabilized nano-silica combined with a reduction in cement content. The results also showed that use of stabilized nano-silica proved to be very advantageous, especially when mixed with silica fume. When they were combined, a synergy effect occurred in the concrete that was of chemical nature in addition to the physical effect of better concrete particle packaging. Analysis by scanning electron microscopy showed the improvement in microstructure of concretes with stabilized nano-silica, which contributed to gains in mechanical properties.
Highlights
High performance concrete is essentially a concrete having a low water/cement ratio to ensure longer service life and adequate mechanical strength specified by design
The application of nanomaterials in concrete production enables the improvement of its properties, since the mechanical strength and the service life of concrete structures are determined by its microstructure [2]
The rheological properties as well as the mechanical properties and microstructure of self-consolidated concrete with the addition of nano-silica were investigated by Maghsoudi et al [9].The results indicated that there was improvement of compressive and flexural strengths and modulus of elasticity of concrete with nano-silica
Summary
High performance concrete is essentially a concrete having a low water/cement ratio to ensure longer service life and adequate mechanical strength specified by design. Grain size of materials used influences the properties of concrete because the strength of a crystalline phase increases with decreasing grain size [1]. The use of nanotechnology can significantly improve the property of various types of materials, such as plastics, metals or carbon fibers, for example. The use of nanomaterials allows for increased contact and surface reactivity, promoting improvement in the properties of the materials. The application of nanomaterials in concrete production enables the improvement of its properties, since the mechanical strength and the service life of concrete structures are determined by its microstructure [2]. The proper use of nanomaterials can still decrease the dimensions and the weight of the concrete structures, and may generate a significant
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