Stone consolidant

C. G. Amorosa and V. Eassina, Stone Decay and Conservation, Cleaning, Consolidation and Protection, Materials Science Monographs no. 11, Elsevier, Amsterdam, 1983. 

Mortars are cements used for bonding together masonry units, such as stones or bricks. When a cement is used to conceal masonry, as a more or less smooth covering on walls, for example, it is referred to as plaster. A very fine plaster, known as stucco, is made of very thin sand or finely comminuted marble. Freshly prepared plasters and stuccos are spread on consolidated masonry to form more or less uniform and smooth layers stucco also provides a smooth and often flat outer coating. 

Pottery, one of the earliest human-made ceramic materials, is actually an artificial form of stone, made by combining the four basic elements recognized by the ancient Greeks earth (clay), water, air, and fire. In fact pottery is made from a circumstantial or deliberately prepared mixture of clay, other solid materials known by the generic name of fillers, and water. When a wet mixture of clay and fillers is formed into a desired shape, then dried and finally heated to high temperature (above 600°C), it becomes consolidated... 

Above the water table, groundwater can also occur in perched aquifer conditions. In these instances, groundwater occurs in relatively permeable soil that is suspended over a relatively low permeability layer of limited lateral extent and thickness at some elevation above the water table. Perched groundwater occurrences are common within the vadose zone high-permeability zones overlie low-permeability zones of limited lateral extent in unconsolidated deposits. However, perched conditions can also occur within low-permeability units overlying zones of higher permeability in both unconsolidated and consolidated deposits. In the latter case, for example, a siltstone or clay stone overlies jointed and fractured bedrock such that groundwater presence reflects the inability of the water to drain at a rate that exceeds replenishment from above. 

Magnetic resonance imaging (MRI) has been applied to the study of the distribution of fluid components (i.e., water or a polymer used as consolidant) in a porous material such as stone or waterlogged wood by a direct visualization of the water or fluid confined in the opaque porous medium [13]. 

Aetna Explosives Comp[Pg.109]

L5. Larson, R. A., Dodge, R. K., Burns, C. P., Lee, E. J., Stone, R. M., Schulman, P., Duggan, D., Davey, F. R., Sobol, R. E., Frankel, S. R., et al. A five-drug remission induction regimen with intensive consolidation for adults with acute lymphoblastic leukemia Cancer and leukemia group B study 8811. Blood 85, 2025-2037 (1995). 

A sediment made up of particles that fall within the sand range is called sand. If consolidated, it is sandstone. Modifiers may be added to refine the description of a particular stone. For instance, if the sand is mostly made of feldspar grains, it would be called a feldspathic sandstone. If mostly quartz, a quartz sandstone. And so on. 

Depending on the nature of X, the products obtained by hydrolysis and intermolecular condensation of the resulting silanols either show water repellant properties (X = alkyl) or allow consolidation of stones without significantly decreasing the spontaneous moisture uptake (X = OR). This is schematically shown in Fig. 2. 

The discussion of silyl ester applications to different stone materials demonstrates that both consolidation and hydrophobation are possible. However, the results of the treatment differ considerably depending on the type of substrate and/or silyl ester. 

Ether-Substituted Triethoxy- and Diethoxymethylsilanes Precursors for Hydrophilic, Elastic Consolidants for Natural Stones... 

Keywords Preservation of Historical Monuments / Stone Consolidants / Hydro-phobation / (3-Alkoxypropyl)triethoxysilanes / (3-AJkoxypropyl)-diethoxymethylsilanes... 

Summary In this paper, (3-alkoxypropyl)triethoxy- and (3-alkoxypropyl)diethoxy-methylsilanes are introduced as a possible basis for hydrophilic, elastic stone consolidants. The preparation of these compounds is described. Addition of (3-alkoxypropyl)diethoxymethylsilanes to commercial stone consolidants reduces the number of shrinking fissures of the resulting Si02-gel. Application of (3-alkoxypropyl)triethoxysilanes without any additives even offers the opportunity to produce hydrophilic, elastic consolidants for natural stones. 

We have investigated the application of ether-substituted triethoxy- and diethoxysilanes ((3-alkoxypropyl)triethoxy- (3-alkoxypropyl)diethoxymethylsilanes) for the preparation of hydrophilic, elastic stone consolidants. 

Fig. 1. Photographs of stone consolidants after polycondensation (a) unmodified stone consolidant (b) modified stone consolidant, elastificated with (3-methoxypropyl)diethoxymethylsilane (c) (3-methoxypropyl)triethoxysilane.

To investigate the elastic properties resulting from ether-functionalized silylester condensates, the diethoxymethyl derivatives were used in 1 1-mixtures with the commercial stone consolidant F510 of Remmers Bauchemie to prepare thick siloxane films in Petri dishes. Fig. lb shows a photograph of the polycondensate obtained from F510 modified with (3-methoxypropyl)diethoxymethylsilane. In comparison with the film produced by hydrolysis and condensation of the unmodified consolidant (Fig. la), considerably less shrinking fissures are observed. 

The ether-substituted triethoxysilanes were brought to polycondensation without addition of stone consolidants yielding films like the one shown in Fig. Ic for the polycondensate of (3-methoxypropyl)triethoxysilane which contains almost no shrinking fissures and therefore is very probably well suited as an elastic, nonhydrophobic consolidant. 

E. Wendler, D. D. Klemm, R. Snethlage, Consolidation and Hydrophobic Treatment of Natural Stone, Fifth International Conference on Durability of Building Materials and Compounds, Brighton 1990. 

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