Characters of interfacial zone of cement paste with additives around aggregate
Kobayashi Koichi; Hattori Atsushi; Miyagawa Toyoaki; Fujii Manabu
Abstract:The strength and the durability of concrete are affected by interfacial zone (also called transition zone) which is porous and made around aggregate. In this paper, this interfacial zone of cement pastes which contain limestone powder (LP) or granulated blast furnace slag (BS) is evaluated with Vickers hardness test and fluorescence microscope to clarify its structure and character. The addition of LP makes the interfacial zone become thinner to some extent as LP reduces bleeding rate because of its large specific surface area. So the thickness of the interfacial zone of cement paste with LP is related more closely to the water-powder ratio than the water-cement ratio. The specific surface area of LP, however, affects the character of the interfacial zone only a little. On the other hand, the specific surface area of BS affects well the character of the interfacial zone. The interfacial zone of specimens with BS of large specific surface area becomes tighter and thinner than the one with BS of small specific surface area, though the interfacial zone of all specimens with BS is tighter than the one without BS. Key Words:interfacial zone, cement paste, limestone powder, granulated blast furnace slag, Vickers hardness, fluorescence microscope