Surface Preparation: A Two-Step Process
November 20, 2007
Surface preparation is a generic term that can be associated with numerous market segments. It is a mechanical process that can range in applications as broad as carpet removal in a hotel lobby, to removing a non-skid surface deck on an aircraft carrier. Although most associate surface preparation with restoration or rehab work, it can also be discovered in new construction.
By definition, surface preparation implies that an existing surface must be prepared prior to the installation or application of a new surface. Surfaces that require a protective or decorative cover need a preparation process. Generally, we can separate surface preparation into a two-stage process: removal and profiling.
Removal refers to the demolition of an existing surface or covering. This can encompass carpet, VCT tile, ceramic tile, wood, rubber, linoleum, epoxies, non-skids, paint, stains and any adhesive surface. Among the most popular removal equipment are strippers (both walk-behind and ride-on), shot blasters (walk-behind and ride-on, in various blast head sizes), grinders, scrapers, scarifiers and planers/shavers.
Profiling refers to a mechanical process of creating a uniformed surface pattern that provides optimal opportunity for adhesion with a new surface/covering. In some cases, removal and profiling can be accomplished in a single step.
Unfortunately, this two-for-one process is the exception and not the rule. As in all phases of construction, specific equipment is engineered for specific applications. The variety of potential surface and profile combinations require an extensive list of equipment in order to provide an effective solution regardless of the situation.
When selecting the appropriate equipment, contractors must first ask themselves:
- What is the existing surface?
- What is the customer’s desired expectation?
- How much time will I have to complete the project?
Therefore, it’s important to research various types of equipment to learn the strengths, design intentions and limitations of each.
Walk-Behind StrippersStripers were designed to efficiently remove floor coverings without damaging the subfloor. In most cases, a new covering will replace the old so there is little need to produce a new surface profile, rather, efficient removal of the old floor covering and any adhesive.
The walk-behind stripper can range from a manual 1-hp, 110-volt electrical model that weighs just over 100 lbs., and is capable of removing light epoxies, linoleum and carpet to a 110- and 220-volt, self-propelled (forward/reverse) model capable of removing glue, ceramic tile and other floor coverings quickly. When comparing the various walk-behind models, the points that separate them are weight, speed, ease of use and durability.
Ride-On StrippersDesigned to achieve high production rates, ride-on models are the workhorses of the floor stripper category. Manufactured in four primary power options (gas, propane, electric and battery), ride-on strippers range in size, speed and capabilities. Although gas- and propane-powered units have historically been the equipment of choice, the trend towards green and cleaner power sources is definitely on the rise.
Battery technology is among the most popular, and has made enormous strides in both daily charge and overall life cycle expectancy. Additional benefits include: safe working environment without toxic or harmful fumes; whisper-quiet operational capabilities; limited down time; various add-on accessories; and can be used in commercial, industrial or residential setting.
Shot BlastShot blasting is the aggressive attack of a surface using various shapes, sizes and hardness densities of materials (such as sand) that utilizes centrifugal force. Material is thrown at high velocity by either a rotating wheel or paddle. The shot, which is contained in a steel-cased housing, is propelled in a downward direction - creating a uniform pattern on the surface. Shot blast technology is capable of removing heavy coatings from either steel or concrete surfaces, and most importantly, the profile resulting from the blast pattern creates an optimal surface for the new surfaces’ adhesion.
It’s imperative that steel liners and wheel kits be replaced for continued work-environment safety and machine longevity.
GrindingAlthough commonly referred to as grinding machines, most modern grinding equipment also performs scraping and concrete polishing. The transition between tasks is accomplished by changing the tooling on the contact heads or disks of the machine. Depending on the task and desired result, scraping, grinding and polishing can be completed independent of each other, or performed in consecutive steps. Again, selecting the appropriate tooling for the application is critical. Because concrete varies in properties, different diamond configuration can either promote or stall the removal or profile process. Hard concrete requires a segment with a softer bond that allows proper performance and avoids diamond glazing. In contrast, soft concrete requires a hard bond.
Grinding yields equal production rates as compared to shot blast, however grinding equipment is capable of performing multiple functions. Ancillary tooling must be well thought-out when considering overall costs.
Polishing ConcretePolished concrete has quickly evolved into a popular floor covering alternative. Recent technology has allowed contractors to grind and polish old, lifeless floors into high-gloss marble, granite, and tile substitutes. The primary appeal to commercial and retail property owners, other than aesthetics, are the significant reductions in maintenance costs. For example, polished concrete costs approximately $.10/sq. ft. annually to maintain.
You can achieve a polished concrete floor through consecutive stages of grinding and polishing. The existing condition of the floor dictates the starting stage, while the customer’s desired final result dictates the final level of polish.
ScarifyingScarifying refers to an aggressive assault on a surface, usually for thick coatings or for trimming high spots. Scarifiers have various styles of interchangeable cutter assemblies that can be used for cleaning, grinding and light- or heavy-milling.
The machines (also known as planers, milling machines or rotary cutters) work by applying a cutting wheel to the concrete surface - typically with a six-shaft cutting drum - that flails the surface, resulting in a textured or roughened finish. Production rates range from 350 to 1,500 sq. ft. per hour (depending on machine size and horsepower) for a 1/8-inch removal depth of 3,500-PSI concrete.
ShaversShavers refer to a gang saw technique used to remove extremely thick coatings. Material is forcibly broken apart with dozens of closely placed cuts into the coatings. Though this process is messy, it is cost efficient compared to the scraper or shot-blasting methods. Production rates vary depending on thickness and the properties of the material to be removed.
Dust CollectionUnfortunately, dust is the by-product of all surface preparation methods. Unless contained properly, dust can cause respiratory problems, irritate and damage vision, and causes excessive wear on machinery and tooling. The Environmental Protection Agency (EPA), as well as other governmental regulatory agencies, has begun aggressively regulating air-borne dust and contaminants. As a result, vacuum systems have become more efficient, as have filters and the dust-filtering process.
When selecting equipment, it’s best to consider the most common surface preparation needs in your geographical region, as well as equipment availability/selection and the functions the equipment will serve. Additional forethought should also be given environmental conditions and availability of jobsite power sources.
Research is the key to any smart business decision so take your time, ask questions and make an educated purchase.