Laboratory Investigation of Ultra-High–Performance Fiber-Reinforced Concrete Modified with Nanomaterials

摘要

High-performance concrete with fibers and nanomaterials possesses mechanical propertiesthat are significantly different from normal-strength concrete materials. This article presentsthe laboratory investigation carried out to study the behavior of ultra-high–performance fiberreinforcedconcrete modified with nanomaterials. The aim of this study was to use an optimumcomposite of nanoalumina, nanolime, nanosilica, and polypropylene fibers to improve themechanical properties of the concrete. The results of compression and flexure tests showedthat the addition of nanolime, nanosilica, and nanoalumina with the optimum mixing ratio couldbe a good alternative to increasing the amount of cement to increase the compressive strengthof the concrete. Adding an extra amount of nanolime in compressive strength should bedone cautiously, but the effect of nanosilica is far less sensitive. The results showed that using30-kg/m~3 nanosilica, 5-kg/m~3 nanolime, and 0.75-kg/m~3 fiber produced the best result. In thetest of concrete durability in acidic and noncorrosive environments, these amounts showedhigher acid resistance. Increasing the amount of nanolime and nanosilica alone increasesthe flexural strength, while increasing the amount of nanomaterials or fiber will reduce it.The effect of increasing the amount of cement on the increase in flexural strength is muchless than increasing the amount of nanomaterials. Also, the relationship between flexuralstrength and compressive strength was estimated for laboratory tests in fiber-reinforced concretemodified with nanomaterials compared with conventional ones. This study has shownthat the American Concrete Institute experimental relationship between compressive strengthand flexural strength is not consistent with this type of ultra-high–performance concrete.