hydration

Studies of moisture loss from hardening monolithic cement concrete have been carried out. It was found that there is no consensus on the critical value of moisture loss from hardening concrete, at which shrinkage and cracking are possible, and there is no common understanding of the possible critical width of the shrinkage crack opening. It is shown that when the concrete hardens in air-dry conditions, its indicators, including durability, decrease by a factor of 2 or more. The critical value of moisture loss from hardening concrete was experimentally determined, which is 2 kg/m2.

The hydraulic properties of ash from incinerated wastepaper sludge were investigated. It is shown that the phase composition of wastepaper sludge after heat treatment is similar to the classical fired carbonate-clay mixes. The necessity of using the combination of retarding admixtures with different action mechanism is shown. The strength in the initial hardening period is ensured by the formation of AFm-phases and ettringite, and subsequently by increasing the role of CSH.

Regulation of hydration processes on nanostructure scale due to the competition adsorption modifying of hydration products by polycarboxylate and adding of nanosized C-S-H nuclei allows promoting homogeneous distribution of solid phase in the structure of cement paste on the micro- and nanolevel, provides the growth of contact amount between hydrates, results rapid structure formation and strength synthesis of Portland cement system.

The paper concerns analysis of theoretical and experimental studies, according to which, in conditions of artificial stone making for buildings purposes (cement, concrete), synthesis of alkaline aluminosilicates similar to natural minerals of zeolitic group occurs. Presence of such new formations in hydration products of standartized type alkaline cements provides their high running abilities and durability.

The glass wastes as a cullet are widely used for the production of building materials mainly as inert aggregate. However finely grained glass powder has the very developed surface, so can not be passive toward cement solutions, what was confirmed in practice. In literature data there is no information about chemical influence of finely grained glass on the process of hardening, especially in an early pre-induction hydration period, which substantially causes the structure formation of cement stone and its properties.