This two-part article deals with the problem of the fissuring of sandstones reconstituted from fine hydraulic mixtures packed and vacuum dried according to a patented procedure. During more than two years, the dimensional variations of these products were measured on slender test pieces reconstituted according to several models proposed for hydraulic concretes.In this part, we present the materials, the procedures used to mould the stones along with the calculations developed to obtain the exact composition of the test pieces. We also give densities, the mechanical strength and recorded time evolution of the deformations for different conservation modes which are representative of the possibilities of the envisaged production. In the second part, we present the method for describing the dimensional variations and the adaptations leading to the introduction of a crack index in choice of the formulas. (C) 2003 Elsevier Ltd. All rights reserved.

The hydraulic mixtures studied in this two-part article are destined for the fabrication of fine reconstituted sandstones. They were obtained from two sands whose size does not exceed 1 mm, white cement, water, and for some, from mineral additions, fibers, and superplasticizer or antishrinkage admixtures. During the elaboration, the method of fabrication created significant vertical variations in the water content, especially in the thick blocks from which were cut the 4×4×70 cm test pieces used in the shrinkage measurements. The first part of the article presented in detail the materials, the formula adjustments, estimates of the rates of hydration and carbonation, and the various measurements. This second part is devoted the models retained for the description of the evolution of the characteristics of these products as well as simulation involving a likely cracking index.