Vinyl tile

Vinyl tile is made of polyvinyl chloride resins and a variety of fillers and pigment. Vinyl tile is satin and abrasion resistant as well as moisture resistant. If properly maintained, vinyl tile usually has a long life span. Vinyl tiles are thermoplastic and may be subject to shrinking or expanding when exposed to excessive heat.

History
The idea of vinyl tiles was first developed in 1909 by Leo Baekeland. Baekeland experimented with a variety of materials before first producing a completely synthetic plastic called Bakelite. Bakelite floor tiles were made by impregnating paper with Bakelite and then subjecting it to high levels of heat. Plastics were not recognized as an acceptable flooring material until the late 1920s. Originally, plastics were only used as a substitute binder in asphalt tiles. By the 1940s, asphalt tiles were made of coumarone-indene (a synthetic resin) and little or no asphalt. Vinylite was the first semiflexible asbestos tile and was exhibited in the Vinylite House at the Century of Progress Exposition in Chicago. Vinyl tile did not find its footing until after World War II. It was used for military applications, like floor mats, which required a large portion of vinyl resin. The military also helped in the development of vinyl tile technology. New advancements caused a decrease in the price of vinyl resin and a rise in vinyl flooring in the hard-surface flooring industry. When vinyl tile was created in rolls, it became a strong competitor for rubber, asphalt, and linoleum flooring. It was easy for manufacturers of asphalt or rubber flooring to break into the vinyl tile industry because the machinery used to produce either could be easily adapted to produce vinyl asbestos tiles.

Manufacturing Process
Vinyl chloride and vinyl acetate are mixed together to produce polyvinyl chloride-acetate, which was the most common plastic resin used in floor tile manufacturing. This material was popular because it could be manufactured with a variety of hardness levels and, because it was clear, had endless color possibilities. Vinyl tiles are all created in roughly the same manner. The materials are mixed under heat and pressure until they are soft dough. The dough is then passed through a calender to thin the material down to the required gauge. Color is then added and can be used for designs effects like variegating or marbling. Square tile pieces are then cut from the hot material using a square knife and ejector plate of punching the piece with a male/female punch. Punching the materials is likely to produce excess amounts of waste but it can be reheated and used again. The tiles are then given time to cool and are ready for installation. If all the material is readily available, it is said that vinyl tile can be produced and ready to leave the manufacturer in less than ten minutes.

Uses and Installation
Though vinyl tiles were first publically introduced in 1933 at the Vinylite House, vinyl tile flooring did not gain popularity until the 1950s. Vinyl tile was used for a variety of purposes including domestic, commercial, industrial, and military. Vinyl tiles can be purchased in three forms-backed vinyl tiles, vinyl composition tile, and vinyl asbestos tile. Vinyl asbestos tile is made of vinyl resin binder, asbestos fiber fillers and crushed limestone aggregate. The material was plasticized, stabilized, and then color was added. Tiles were made stronger because of the 7R grade asbestos fibers that were waste products of the asbestos mining industry. Asbestos fibers tended to lend a gray tint to the vinyl asbestos tiles, which proved to be the one color limitation. Backed vinyl tile is composed of vinyl resins, pigments, fillers, and plasticizers that have been applied to a backing that is meant to provide comfort and resilience. Backed vinyl tiles can also be a term used to describe a cushioned vinyl that is formed by applying a vinyl laminate to a filled cheap backing. Backing tiles can include but are not limited to: asphalt impregnated felt, cork, and solid vinyl formed from reused scraps. Solid vinyl tiles were introduced in 1945. Solid vinyl tiles were more expensive that the other two types of vinyl tile. Solid vinyl tiles were made of polyvinyl chloride resin, plasticizers, fillers, and pigments that were heated and pressed. This tile is extremely tough but flexible. Translucent or transparent vinyl tiles are made of up to 100 percent binder and are the most expensive of the vinyl tiles. Vinyl tiles are traditionally applied to a rigid base and may require some type of underlay if applied to a wood base. Asphaltic adhesives are used to fix tiles to the subfloor and should be water resistant. An impervious layer is formed between the subfloor and the tile backing.

Conservation
Each variety of tiles, whether it is vinyl asbestos, vinyl composition, or solid vinyl, has its own chemical composition and physical properties that make it ideal for some environments and inappropriate for others. Poor design and improper specifications are usually the main factor in the deterioration of vinyl tiles. Moist environments, poor workmanship, and unacceptable substrate material or preparation are common problems that can destroy vinyl tile. Bubbling, cracking, and leaking of the adhesive through the joints are a result of the above listed problems and are indicators of severe problems.

Deterioration
The process in which the binding component in vinyl tile degrades is known as dehydrochlorination. This deterioration is visibly marked by the yellowing of the vinyl tile when exposed to direct sunlight. Cleaving occurs when carbon-carbon bonds break down due to exposure to ultra-violet light. Cleaving of the polymer backbone is evidenced by fading or chalking of the tile’s surface and can be caused by the use of ultraviolet-stabilizer additives in the vinyl tile. Extreme amounts of moisture are likely to cause swelling and stress on the adhesive bonding planes. The material is the likely to breakdown chemically or physically and can cause the substrate materials to deteriorate. Moisture may also cause oily plasticizers to interfere with the interfacial bonding between the adhesive and the tile or the adhesive and the substrate. If water is allowed to reach the substrate faster than the vinyl tile flooring, failure will occur. Bubbling and localized delamination often occurs when water vapor reaches the substrate quicker than the vinyl tile. Using an inefficient vapor retarder rather than a true-vapor barrier under the slab can also lead the moisture-related failure. Before any repair is done, the cause of the failure should be identified. Existing conditions should first be evaluated and the least evasive action should be considered and implemented. Original specifications and construction records may prove helpful in determining the reason for the deterioration of the materials. Safety data sheets should be reviewed to complement site and lab studies. On-site condition surveys should be taken to determine the site of failure and destructive exploration may be necessary. Photographic documentation should be taken for studying, as should samples. The sample should have a section of the substrate, the leveling course, the adhesive, and the tile. Physical testing can be done to determine the adhesion characteristics of existing tile. Moisture emission rates should also be studied in the field to understand what should be added or removed from the structure. Tests can be easily performed but can be inadequate for any real conclusion to be developed. Electronic moisture meters can provide information about excessive moisture. Moisture emission test kits are commonly used to determine if the installation of vinyl tile is possible. The Moisture Emission Test Unit was developed to measure the rate of which water vapor permeates the concrete slab. Emission rates are calculated in terms of pounds of water per 1,000 square feet in a time frame of 24 hours. If the amount of moisture measured after the 24 hour time period exceeds three pounds of water, the area is not suitable for organic-based adhesives or vinyl tile flooring. Petro-graphic and microscopic laboratory studies can be used to determine the cause of failure and the current condition of the installed flooring. Also, these studies offer information about what type of failure the floor has suffered; whether it was adhesive or cohesive failure or a combination of the two. Fourier transform infrared spectrophotometry is also useful for identifying organic compounds and polymeric materials. This is helpful in identifying the type of chemical adhesive used and whether it has had a durable life or if it has been degraded in its environment.

Conservation Techniques
Vinyl tile floorings are durable and usually require little maintenance. Sweeping or mopping with a damp mop to remove abrasive dirt and mild staining should be done regularly. Oil, sand, or other abrasive sweeping materials should be avoided as they can scratch the surface. Alkaline cleaners can destroy binders and fillers and can fade pigments and should therefore be avoided. Synthetic detergents in a diluted formula tend to be very effective. Tiles that have been cleaned should be rinsed, dried, and polished the maintain pores and prevent absorption of foreign liquids. Worn vinyl asbestos and vinyl composition should be sealed to extend the service life. Before repairing any kind of damage, it is important to identify the cause of the damage to prevent further issues. On-site mock-ups of several repair schemes can be done to test the durability of a variety of repairs. When purchasing replacement tiles or adhesives, previous problems should be reported to the manufacturer. Moisture emission rates should be studied to understand what effect it will have on future efforts to conserve vinyl tile floor. Any material that may contain asbestos should have samples sent to the U.S Environmental Protection Agency as asbestos has been known to produce carcinogens and may cause health problems. If an existing floor contains asbestos and the floor must be removed, an asbestos abatement program should be followed in accordance with federal, state, and local regulations for handling the material and proper disposal. Vinyl asbestos flooring that is in good condition should be left in place and protected by a sealer. Replacement tiles can be used to replace single tiles that require no mechanical or chemical removal, thus avoiding total abatement. Conserving vinyl tile installations may require pieces to be removed and replaced in certain areas. Finding these replacement pieces that match the existing floor may be possible by contacting the manufacturer. Custom orders may be possible but costly. Tile adhesive should be researched especially when replacing a small portion of an existing vinyl tile installation. Adhesive characteristics should be as close to the original and its durability and alkaline resistance should be carefully matched. Adhesives may be asphaltic mastic, latex emulsion, and synthetic hydrocarbon resins. Any adhesive that contains polyvinyl acetate binder components are likely to be deteriorated by chemicals. The contractor is the party most responsible for quality installation. Repairs should concentrate on maximizing the tile’s adhesion to the substrate. The substrate’s moisture emission rate should be checked before any progress has been made in installation and residue from the previous pieces should be completely removed. Once replacement pieces have been installed, the existing pieces can be polished to create a more uniformed look. Finishing waxes are likely to limit the perception of existing scratches and cracks. Manufacturers will commonly suggest a cleaning approach and it should not be deviated from. Reusing existing tiles is normally a possibility. Asbestos tile are likely to be brittle and may not be capable of recycling into a new installation. Reconditioning cracked or curled-edged pieces will normally restore them to their previously flat state. Subjecting tiles to loads on flat surfaces in a warm or humid climate will normally force the tiles to retake their natural shape.

Replacement
If vinyl composition or vinyl asbestos tile has been installed on a concrete substrate that has a high moisture emission rate, it may be prone to long-term failure. Moisture emission may be caused by a lack of a true vapor barrier beneath the slab or if water has infiltrated the subflooring. If the concrete can be forced to dry until the moisture levels are acceptable for installation, remedial vinyl tile can be installed in place of the vinyl composition or the vinyl asbestos. A french drainage system can be installed under an existing slab which will drain water away from the slab. Though this process can be effective, it is unlikely that the moisture levels will be low enough for the application of remedial tile. Installing a true vapor barrier system can be installed on an existing substrate and then covered by a high-performance overlay. Vinyl tile can then be reinstalled over the new overlay.

Standards and specifications

 * ASTM F-1066 - Standard Specification for Vinyl Composition Tile (VCT)
 * ASTM F-710 - Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring
 * ASTM F-1482 - Standard Practice for Installation and Preparation of Panel Type Underlayments to Receive Resilient Flooring
 * ASTM F-1869 - Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride
 * ASTM F-2170 - Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In Situ Probes
 * ASTM F-2420 - Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement.
 * ACI 302.1R - Guide for Concrete Floor and Slab Construction 117R Standard Tolerances for Concrete Construction and Materials
 * Resilient Floor Covering Institute (RFCI) Recommended Work Practices for the Removal of Resilient Floor Coverings
 * MASTERSPEC Guide Spec Section 03300, “Cast-In-Place Concrete”