Microstrain distribution in calcium hydroxide present in the interfacial transition zone

This article develops an approach for estimating the microstrain distributi on along the thickness of the interfacial transition zone (ITZ) formed betw een aggregate and cement paste. This approach is dependent on the effective ness of the X-ray's penetration depth into the sample and on the order of a ctive reflection from calcium hydroxide (CH) texture. The ITZ was simulated by first casting cement paste on top of a polished flat substrate of grani te. Next, the composite specimen was cured under saturated conditions and t hen broken at the substrate-cement paste interface for X-ray diffraction ex amination. Four orders (001, 002, 003, and 004) of reflection CoKalpha from the CH texture were recorded. The experimental results indicate that the s izes and the microstrain of the CH crystallite decrease with increasing dis tance from the aggregate-cement paste interface. (C) 2000 Elsevier Science Ltd. All rights reserved.