Inta Vitina

Hydration of Cement Minerals in a Hydraulic Dolomitic Binder

Dolomitic Roman cement was a widely used binder for construction purposes during the late 19th/ early 20th century in territory of Latvia. Because of its hydraulic properties and fast setting it was especially favorable for the usage for the cast elements of Art Nouveau style facades. The production of the material was discontinued in the middle of the 20th century. Nevertheless, there is a need of compatible material for restoration purposes that is not currently commercially available. A compatible binder has been synthesized from mixture of dolomite flour and clay. The research gives an insight of the ongoing chemical processes during the hydration of the cement minerals in the binder. The influence of clay content in compositions and of firing temperature on the physico-chemical properties and mineralogical composition of obtained material is estimated.

Chemical Characterization of Lime-Based Binders in Historic Buildings of Latvia

The aim of this research is to investigate the chemical composition of stone materials of several local historic buildings with a purpose of elaboration of restoration strategy, including the choice of restoration materials. Most of the examined mortars are lime- based hydraulic mortars, characteristic of the architecture of 19th/20th century. Pure aerial lime binders show reduced compatibility with historic materials, that is why lime binders with pozzolan additive (cement) are an appropriate choice for restoration. In order to examine the changes of hydraulicity (i.e. the property of binders to harden when exposed to water) of perspective restoration binders, a series of blended lime-cement mixtures were synthesized with growing content of cement (up to 10% by weight). A significant relationship between cement content and hydraulic properties has been shown.

Chemical and Physical Processes in the Synthesis of Romancement from Clay and Dolomite

This work deals with the synthesis of binder, similar to historic dolomitic romancement, from mixture of clay and dolomite instead of traditionally used marlstone, thus widening the range of raw materials. In the territory of Latvia dolomitic romancement was widely known and applied in the construction of buildings since late 19th till the middle of 20th century. Nowadays the local dolomitic marlstone is not sufficiently available. As the scientists have faced the problem adjusting compatible material for restoration of historical buildings of given time period, research is done with the aim to investigate the synthesis of romancement type binder from widespread local mineral raw materials for the restoration purposes. In given paper the chemical and physical processes in the synthesis and also obtained properties are discussed.

Stone material investigations of the Riga Stock Exchange building

This paper deals with the stone material investigation of former Riga Stock Exchange building and presents the following aspects: characterization of materials, analyses of mortars for sealing and cladding of artificial marble, decors, bricks, render of sealing, analyses of soluble salts, analyses of deteriorated granite surface of foundation. The last damage by fire was in 1979 which caused the collapse of the roof and consequently an infiltration of rain water. The conditions of the objects were found in very bad condition-deterioration represented by salt efflorescences, cracking and in very large areas there was a complete loss of the artificial marble (stucco marble).