Masonry surfaces

Masonry products have been widely used in the construction industry and include building materials such as cementious materials, concrete, brick, tile, stone, grout, and like substances. Driveways, garage flooring, concrete block, brick fronts, fireplaces, fireplace hearths, as well as tiled floor, wall and counter top surfaces are exemplary applications. Masonry surfaces are porous and if left unprotected can deteriorate from exposure to water and they can become discolored. For example, water penetration can cause spalling or lead to discoloration via microbial growth. Tiles and grouts employed in homes come in contact with various foods and liquids, e.g., fruit juice, coffee, oils, ketchup, mustard, etc. that can cause discoloration. 

Motor oils, brake-oils, and transmission fluids can cause the discoloration of garage floors. Therefore, it has been common practice to coat masonry surfaces with materials capable of rendering them resistant to water, oils, and other contaminants (23). 

Exemplary materials for the waterproofing of masonry surfaces are waterproof membranes such as poly(vinyl chloride), PE, butyl rubber, and sealants such as tar, asphalt, paints, poly(urethane), epoxy or mastics. While these waterproofing agents can offer excellent resistance to water penetration and other contaminants, they can alter the appearance of the masonry surface, e.g., they may change the color of the surface or leave it with a shine. Waterproofing treatments can also trap moisture within the masonry surface and promote spalling. 

Exemplary water-repellent treatments for masonry surfaces include metal stearates, oils, waxes, acrylates (both polymers and monomers), silicones (solvent-based and emulsion), siliconates, silanes and, fluorochemicals. In contrast, to waterproofing coatings, water-repellent coatings, because they are permeable to water vapor, do not trap moisture and, therefore they can reduce spalling. In addition most water-repellent coatings do not alter the appearance of a porous masonry. 

Employ environmentally compatible aqueous based compositions as a means of affording substantially non-discoloring water-repellent films to masonry surfaces. 

Primers are pigmented coatings that are applied to new surfaces or to old cleaned surfaces, prior to the application of undercoats or top coats. Its main functions are to achieve adequate adhesion to the substrate and to provide good intercoat adhesion for subsequent coats. They are specifically formulated for particular substrates such as wood, metals, concrete, and other masonry surfaces. Concrete and other masonry surfaces are alkaline and often require special surface treatments. For etching and neutralization of these alkaline surfaces, hydrochloric or phosphoric acid washing is usually done. 

Test Methods. Tests for water repeUency of concrete and masonry have been described by several authors (72,94). The National Bureau of Standards (NBS) evaluated fifty-five clear water repeUents for masonry surfaces (95). Performance tests included water absorption, water-vapor transmission, resistance to efflorescence, change in appearance, and durability to accelerated and outdoor weathering. More recently, the National Cooperative Highway Research Program conducted a study of several organic and sihcone water-repeUent treatments. The results are communicated in Report 244 (96). The testing procedure used in this study is now a popular method for evaluating water-repeUent treatments on concrete. 

It is also possible to reface and even take out variations in concrete and masonry surfaces and bridge shrinkage cracks. Such coatings find application on walls, buildings, roofs, water tanks, reservoirs and so on. 

S Biological corrosion. Damp masonry surfaces allow the growth of micro-organisms such as bacteria, moulds, mosses, algae and lichens (Figure 6.11). With an efficient metabolism the separation of the products of metabolism can result in the deposition of salts. If walls are not treated the effect is an uninhabitable building. 

Where a masonry surfacing is laid over a membrane (as for instance brick over a hot asphalt-coated concrete floor), the membrane provides the sliding... 

Chem. Descrip. Epoxy resin sol n., MIBK, xylene Uses Epoxy for R.T.-curing industrial maintenance coatings incl. clears, primers, masonry surfacers, gloss and semigloss enamels Features Produces systems with exc. chem. resist., corrosion resist., and low color... 

Styrene-acrylic, waterproof masonry surface control agent, aq.-curable... 

Latex or emulsion paints Decoration of plaster or masonry surfaces Various coalescing solvents e.g. BEE BEEAc Hexylene glycol Water Dries by evaporation or migration of water followed by coalescence of latex particles. This may be assisted by addition of small quantities of high boiling coalescing solvents ... 

When FRP fabrics or sheets are applied on masonry surfaces, the total lack of transpiration that characterizes composite materials should not be neglected. For this reason, the structural reinforcement carried out with such materials should not concern extended surfaces of the wall face, in order to preserve suitable transpiration of the system. The problem of suitable transpiration of masonry supports can be solved by using steel-reinforced grout (SRG) or fiber-reinforced grout (FRG) materials composed of suitably prepared matrices. 

In the case of operations on a masonry surface not requiring any restoration, but possibly just being of a poor quahty, an evaluation of the possible application of a consolidating agent on it before the laying of the primer is advisable. 

Silicones, water repellent in water R R N N R Used on masonry surfaces. 

The process begins with raking of the masonry mortar joints to a depth of in.. Dust and debris were then washed away and the walls were predampened. Contaminated surfaces were to be scored with an axe. Stucco was then prepared in a fluid, workable consistency, and was applied in two hfts. The first lift was intended to fill the raked masonry joints and to provide a thin base-coat over the masonry surface. The second coat was installed over the soft base coat to a depth of j in. and was immediately finished. The stucco was then cured for several days. The stucco recipe in Table 6 is cited ... 

The incompatibility of resins to masonry structure has an impact to the bond of FRP on masonry surface. Moreover, FRP may create secondary side effects that make the benefits of reversibility questionable. This occurs because of the lack of vapor permeability that leads to moisture accumulation inside the masoruy mass which favors deterioration phenomena, particularly in the case of large masonry area rapping with FRP. Furthermore, FRP or AR fiber glass textiles exhibit brittle failure mechanism when their bonding is based on adhesion and friction. In fiber grids with cement-based matrix, these effects are mitigated. 

Efflorescence refers to the deposit of water-soluble salts on the outside of painted masonry surfaces, such as stucco, concrete, volcanic-ash cinder block, and mortar between blocks. Water-soluble salts are leached out of the masonry when water penetrates the masomy from the inside. When water evaporates from the painted surface, it leaves a deposit of salts. Although the salts can be washed off with a stream of water, they will form again unless the source of water behind the paint is removed. Many times, the source is a leaking roof... 

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