Adhesive troweling

Generally, polymer latexes used as cement modifiers are not toxic, are safe materials to handle and require no special precautions. However, because they have an excellent adhesion to various materials, even to metals, all the equipment and tools such as mixers, trowels, and vibrators should be washed down or cleaned immediately with water after use. For concrete requiring formwork, it is advisable to use the most effective mold-release agents, e.g., silicone wax or grease [87, 96]. 

Epoxy adhesive formulations demand a great variety of solvents and diluents with a wide range of evaporation rates, solvent strengths, and dispersion powers. These variations are required due to (1) the many types of epoxy resins, curing agents, and possible organic additives that can be used within a formulation and (2) the many different possible methods that can be used to apply the epoxy to the substrate (brush, spray, trowel, etc.). 

It provides for certain application characteristics of the adhesive (brush, spray, trowel,... 

Control of Viscosity. To ensure that adhesives and sealants function well during their application and end use, the formulator must be able to control the flow properties of the product. The challenge that faces the formulator is that the adhesive or sealant may need different flow characteristics at different times. For example, adhesives must flow readily so that they can be evenly applied to a substrate and wet out the surface. Yet, there should not be an excess of penetration into porous substrates, nor should the adhesive run or bleed to create a starved joint. Certain adhesives and sealants must be capable of convenient flow application by trowel or extrusion, but they must also exhibit sag and slump resistance, once applied. Therefore, the flow properties, or rheology, of the material must fit the desired method of application. 

The epoxy adhesives are usually applied by simple extrusion from dispensing nozzles, brushing, or troweling. However, spray equipment may be used in certain applications. Conventional spray equipment is used with solvent-borne epoxy adhesives, but frequent cleaning is generally required. For fast-reacting systems, dual-nozzle spray equipment is available. 

Pastes and Mastics. Bulk adhesives such as pastes or mastics are the simplest and most reproducible adhesive to apply. They produce heavy coatings that fill voids, bridge gaps, or seal joints. They can be in the form of high-viscosity extrudable liquid or a trowelable mastic. 

These systems can be troweled on or extruded through a caulking gun. Little operator skill is required. Since the thixotropic nature of the paste prevents it from flowing excessively, application is usually clean, and not much waste is generated. With trowel application, the depth of notch and the spaces between them help regulate the amount of adhesive applied. Shallow, rounded, and closely spaced notches are often used with lower-viscosity adhesives to allow the lines of adhesive to flow together and form a continuous, unbroken film. 

Solvent-free epoxy (spray or trowel) 100 500-625 2 h 6h High resistance against tidal and impact actions, good oil and water resistance, good adhesion to many surfaces... 

The finish of the concrete can be critical. A dense steel troweled finish will not provide the porosity required for adhesion of some of the materials used as membranes. A carpet float finish will provide just about the correct texture. Do not use magnesium floats as this will close the surface and prevent the escape of "bleed" water. Do not use curing compounds or those intended to prevent evaporation of water. These are incompatible with some bedding or membrane materials resulting in very poor adhesion. 

To install the block with adhesive/membrane on properly prepared substrates, the adhesive/membrane is applied to the substrate at a minimum Vie" thickness with a trowel. The adhesive/membrane is then troweled on the back, sides and end of the block also at a minimum Me" thickness. The coated block... 

Syntactic silicone foams have also been formed. They cure at room temperature or at slightly elevated temperatures and become flexible insulators and ablators. They can be cut, trowelled, molded, or air-injected into place, and oued pieces can be bonded to substrates by using RTV silicone adhesives (13). 

The mechanical troweling apparatus for preparation of adhesion test specimen of plastering materials to concrete substrate has been proposed by R.NANIWA. Workability of PLCM were estimated by 3 rheological characteristics horizontal reaction force Ftr, vertical reaction force Fnr and reaction moment Mr at the grip (supporting point) were measured. Fig. 5 shows the schema of troweling motion and the apparatus in this test method. Some examples of test... 

The mechanical troweling apparatus for preparation of adhesion specimen of plastering material to concrete substrate can estimate satisfactorily the workability of PLCM with visco-elastic behavior. Workability of existing PLCM is not always sufficient to apply. It is necessary to improve the characteristics of PLCM. 

Hada, K et al. (1994) Mechanical Troweling Apparatus for preparation of Adhesion Test Specimen of Plastering Materials. Annual Convention of Architectural Institute of Japan, PP. 1345-1346. 

Adhesives can vaiy from low viscosity to high viscosity, depending on formulation and application. Thicket adhesives used for floor tiling are stiff when first put onto a trowel but spread easily over the floor. This ease of application is important to the user, although the quality of the adhesive is possibly judged more by its stiffiiess, which relates to yield stress value. 

A primer adhesive is first applied to a properly prepared concrete surface. A thin coat of epoxy mortar is then applied with a trowel. While this thin coat is still wet, a fiberglass membrane is rolled into the mortar. The edges of the membrane should be overlapped 2 inches. The mortar will squeeze up through the voids in the fiberglass mesh, resulting in adhesive base to which the final epoxy mortar will adhere. While this first application of mortar is still tacky, the second layer of epoxy mortar is applied over the glass cloth. This second layer may then be screeded and leveled. ... 

Solution adhesives are applied at 10-25% total solids content by spray, doctor knife, reverse roll coater, roller, or by spatula or trowel. The adhesive is dried at room temperature or in air ovens, care being taken to eliminate the fire and health hazards associated with some solvents. 

Uses Diiuent for epoxy systems, for soiv.-free coatings and floorings Features General purpose low toxicity improves adhesion to most substrates incl. oily metal ( 5-10 phr) improves trowelability of epoxy mortars add to resin or curing agent Properties Gardner7 max. liq. sp.gr. 1.04 dens. 8.6 Ih/gal vise. 100cps... 

Uses Acrylic for hydraulically setting systems, PCC-mortars, plasters for trowel applies., primers, sealers, floor screeds/self-leveling compds., industrial floorings, building adhesives Features Free from film-forming aids, soivs., and plasticizers Properties Whitish liq. ammonia odor dilutable in water dens. 1.05-... 

Uses Binder in pigmented emulsion paints, other surf, coatings, n. resin-bound piasters, exterior/interior paints, cement-contg. adhesives in thermai insuiation boards, cement-contg. troweling and reinforcement... 

Chem. Descrip. Ethylene/vinyl laurate/vinyl chloride terpolymer with polyvinyl alcohol stabilizer and mineral filler antiblocking agent Uses Binder, water repellent in conjunction with inorg. binders in plasters. Joint mortars, troweling compds., tile and construction adhesives, adhesives for external insulation and finishing systems sole binder in plasters, paints, adhesives modifier, adhesion promoter, plasticizer, impact resist, aid for gypsum and anhydrite Features Imparts hydrophobic props. enhances adhesion, flex, str., plasticity, abrasion resist., and workability contains no soivs., plasticizers, of film-forming aids... 

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