ABSTRACT
Abstract A contribution to the knowledge on the influence of the type of binding and rock on the character and properties of the contact zone with special respect to the aplication of the gypsum free cements. For experimental investigation of zone properties five types of rocks were used and three types of cements. Character of contact zone was investigated with the aid of microhardness measurement method, scanning electron microscope test and cement-rock bond test. From experimental results follows that the character of the contact zone depends on the type of the binding and rock used. In the case of gypsum-free cement the contact zone has expresively compact character. The microhardness data depends on the type of the uses binder and rock. Microhardness data depends on the type of used binder and rock. Microhardness of gypsum-free cements exceeds generally microhardness of the Portland cement in the contact zone so as in the cement body. Bond strength of gypsum-free cement is twofold in comparison with corresponding data of Portland cements. Bond strength of Portland cements is influenced by their composition, so as by composition of rocks. The bond strength of gypsum-free cements depends much more on the surface relief. Keywords: gypsum-free cement, cement-rock composites, interfacial transition zone, microhardness, scanning electron microscope, bond strength
1 Introduction
In spite of the fact that there are great differences in bond strength between cement and different rocks known at 20tieth of this century aggregates in concrete was generaly considered as inert. Knowledge on some reactions between aggregates and cement led to the intensive study of interfacial transition zone. Experimentally was proven that connection between aggregates and cement in concrete influences not only physical and mechanical properties of mortars and concretes but also pronouncedly their durability [1-10].
