Get this from a library! Alkoxysilanes and the consolidation of stone. [George Wheeler; Getty Conservation Institute.]. Stone is one of the oldest building materials, and its conservation ranks as one of the most challenging in the field. The use of alkoxysilanes in the conservation. Permalink: ; Title: Alkoxysilanes and the consolidation of stone / George Wheeler ; with annotated bibliography by.
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The aim of this revised method is to achieve the deposition of barium carbonate as a binder deeply within the pores of the stone by keeping the barium hydroxide solution in contact with the stone for a prolonged period, usually 2 to 3 weeks.
Bulk infiltration is a technique whereby holes are drilled into the wall and funnels are used to deliver consolidant to a substantial depth where impregnation is obtained.
Current ot on consolidation of deteriorated stone contains numerous projects which have utilized ethyl silicates as consolidants with significant success.
Without constant maintenance and repair, there is little hope in preserving mudbrick structures, regardless of the treatment performed. Epoxy resins are now commercially available with satisfactorily low viscosities. Limewater is a clear saturated calcium hydroxide solution. These products are in the form of one-pack materials. Conservare Kansas City, Kansas: Authors theorize that a slow dehydration takes place which takes the clay to a form that prevents the water-based curing mechanism from occuring.
The repair work may include pinning, mortar filling, fracture grouting, repointing, adhering detached pieces, and application of biocides, etc. Ethyl silicate and its combination with organo- silicon hydrophobic agents has been commercially available in western Europe since and thereafter in the United States and Canada. Current literature includes an increasing number of case studies where alkoxysilanes have been used as consolidants. Clifton ” Laboratory Evaluation of Stone Consolidants, ” p.
Bulk infiltration was used in combination with surface application of consolidant by brushing. Partially polymerized ethyl silicate is widely marketed. C — — Modulus consilidation Rupture. NBS Technical Note This volume, the first to comprehensively cover alkoxysilanes in stone consolidation, synthesizes the subject’s vast and extensive literature, which ranges from production of alkoxysilanes in the nineteenth century to the extensive contributions from sol-gel science in the s and s.
Alkoxysilanes and the consolidation of stone – Ghent University Library
The object is wrapped in a poultice and sealed air tight by means of a polyethylene film. However, if the liquid is too volatile, it will evaporate before a sufficient penetration is achieved. Donsolidation choosing a solvent and catalyst to increase the rate of polymerization, one should be aware of the fact that they must not react with the substrate and leave any soluble residue in it which can cause future decay.
However, in a later report R.
Once the above testing procedures have been completed, evaluation of the laboratory data in conjunction with the alkodysilanes of existing conditions of the masonry can assist in identifying the causes of decay, the suitability of the substrate for consolidation and finally in selecting alooxysilanes appropriate consolidant s for the masonry conditions present at the job site. In response to this, numerous research projects, publications and conferences dealing with stone have been facilitating the worid wide exchange of information.
Aroundsome of the commercial products available from England through Silicon Organic Developments Ltd. Trimethoxymethylsilane consokidation structurally similar to triethoxymethylsilane except for the substitution of methoxy groups for the ethoxy groups.
Waxes have been used in the alkoxysilames of a solution or in the form of melted mixtures. German literature contains numerous enthusiastic reports about the successful application of silicic acid based products to consolidate deteriorated German sandstones. Barium hydroxide [Ba OH 2], formerly termed baryta, solution has been used in place of calcium hydroxide solution for the purpose of hardening and protecting weathered stone since the 19th century.
As is obvious from the consolieation discussion, controversial results have been obtained from different research and experiments regarding the use of alkoxysilanes for the conservation of earthen building materials.
History of the Use of Alkoxysilanes for Stone Consolidation 54 3. When the alkoxysilanes are deposited in the stone, polymerization proceeds by two steps which are hydrolysis and condensation.
Additionally, this technique has been found to alter the surface color or texture of stone in many cases. Winkler has introduced thin discs for testing the durability and strength of stone.
Alkoxysilanes and the consolidation of stone
alkoxysulanes The Victoria and Albert Museum in London has been actively involved in the problems of stone deterioration and its treatment since The product was not recommended for use where there is rising damp.
They are consoliation consolidants, alkoxysilanes, synthetic organic polymersand waxes. The consolidating substance should have the ability to penetrate easily and deeply into the weathered stone. Historical overview stonne The chemistry of physics of alkoxysilanes and their gels — Essential ingredients — Addition of water — Catalysis — Gelation, syneresis, and ripening — Drying — The influence of stone type — Mineral composition — The clay problem — Other stone types — Other issues of structure — Darkening and color changes consolidxtion Commercial and noncommercial formulations — Commercial formulations — Noncommercial formulations — Practice — Preconsolidation — Moisture and wetness — Biological growth — Salts — Application techniques — Consumption — Application schedule — Conflicting activities — Darkening and color changes — Application on black crusts — Water repellents — Safety and storage — Laboratory and field evaluation of service life — Recent developments and final thoughts.
The measured compressive strength and tensile strength of treated and untreated masonry samples are compared to estimate the improvement in the mechanical properties of masonry following consolidation and to determine the consolidating abilities of the consolidant o Salt Crystallization: Chiari, ” Consolidation of Adobe with Wnd Silicate: The increasing interest in the conservation of historic structures and the accelerating deterioration of the stone of exposed sculptures and buildings have necessitated an consolidatiin of the mechanisms responsible for stone decay to develop the possibilities of optimum stone protection.
As part of this study, O.
Full text of “Alkoxysilanes consolidation of stone and earthen building materials”
In the absence of catalysts, the polymerization is too slow for practical field use. Many questions can be raised such as: Necessary precautions in application are not convenient for large projects. It has been suggested that air and surface temperatures should be from 50 degrees F to 85 degrees F during application. Among the various products available at the alkoxyzilanes, ethyl silicate seemed to give the best preliminary results.
Since the use of synthetic organic polymers as stone consolidants is a recent development, dating back to the early ‘s, there is not much known of their long-term effects. Besides providing a short-term evaluation of the recommended consolidation treatment slaboratory programs have the advantage that test conditions can be adjusted to simulate the specific environment and climate to which the consolidant will be exposed.
Price, on the other hand, has proposed the specific depth of penetration to be at least 25 mm. Methyl methacrylate and butyl methacrylate are the acrylic monomers that have been most widely used to consolidate stone and alkoxysilahes. There are several publications on the evaluation of this work.