General Polymers Selecting a System

General Polymers Selecting a System

Polymer Flooring

Selecting Polymers Flooring Systems

By: James Hendley, General Polymers

(Published in Plant Engineering June 1995)

Each different resinous flooring system placed on a concrete slab is formulated to withstand a specific type of environment. In addition, the levels of support and service from manufacturer along with, technical competence, of the installing contractor may vary significantly. Taking time to evaluate and analyze these factors, along with a determination of the anticipated operating conditions versus available material options, ensures longer floor life, lower maintenance costs, and better performance.

Know the Substrate

New and existing concrete must be properly evaluated before installing a coating or overlay system. Concrete is a versatile and strong building material, but it has a host of potential problems. Cracking, crazing and map cracking, low resistance to wear, dusting, scaling, popouts, blisters, spalling, moisture vapor transmission, ponding and inadequate slope to drain, curling and warping, efflorescence, and freeze/thaw cycles are all indications of concrete problems and detrimental to the integrity of concrete.

A basic understanding of concrete’s design, placement, curing, and finishing techniques is necessary. This allows the proactive owner/engineer to positively impact the concrete specification and installation on new construction which ultimately impacts the strength and permeability of their concrete. This paper will focus on the basic information necessary to help insure that the resinous floor and wall systems which best meet your needs are selected. In order to do this, a basic guide for concrete design is discussed, followed by criteria for protective system selection. Finally, an overview of available resin technologies and their relative strengths and weakness is discussed.

Concrete, Stronger than ever?

With all of the rapid advances today in science and technology, it is alarming to note that some experts believe that the quality i.e. durability of concrete, has been going the wrong direction in the last 20 years. Shilstone and Shilstone, Authors of many articles and lectures at ACI (American Concrete Institute), believe the reasons for this are as follows:

  • A reduction in academic programs offered in architectural and engineering programs;
  • An over emphasis of measurable values, such as 28 day compressive strength. By itself, this does not mean much in terms of performance.
  • A view towards up front cost and schedules (speed) which negate a view towards value.
  • Ignorance of historical information concerning quality concrete still serviceable after decades of use.
  • The view of most contractors that they will meet specs, rather than a team approach to providing value and meeting owners’ needs.
  • A number of parameters should be scrutinized and carefully controlled to insure durable concrete. A water to cement ratio w/c of less than 0.45 allows enough water to facilitate placement, but not excessive amounts which cause excessive capillarity and significant decrease in physical strength. Aggregates should be graded to provide proper packing and consolidation proper grading and proportion of aggregates provide concrete strength and resistance to cracking. ASTM C 33 provides guidelines for proper aggregate graduation.

Concrete additives such as calcium chloride and sodium chloride must not be used as these products attract moisture after becoming part of the of the concrete mix. The affinity of moisture of these additives can lead to moisture vapor transmission problems in concrete where they are used. The strength of the bond of resinous systems to the concrete is directly related to the strength of the concrete. A compressive strength of 5,000 psi provides sufficient strength for resinous systems.

General Polymers Selecting a System

The Finish

The key to a successful finish floor acceptance of a non-permeable flooring system is to provide minimum disruption to the even distribution of paste and aggregate. Compaction is important but it should be kept to a minimum to prevent bringing too much paste to the surface. Too severe a finish of any kind will bring water and paste to the surface. This will be the weakest, most porous and crack-ridden portion of the concrete. These reasons have everything to do with a high water / cement ratio, and high paste concentration.

Concrete Specification Review

Concrete specification should include the following to maximize the probability of successful bonding of non-permeable floor coverings:

    Water / cement ratio should be .45 Aggregate must be well graded, to minimize total water and cement (paste) ASTM C 33 Compressive strength, minimum 5,000 psi Elimination of all CaCl & NaCl 0% Concrete Density 140 lbs. /ft3 Slump (Rheology) 4″ Air _6.5%

Placement

The preferred placement which should always be specified in compaction and a light steel trowel finish to minimize the disruption of the paste and aggregate distribution. The best finish is a light steel trowel finish, as this will provide for the least amount of paste brought to the surface. Any other type of finish will require more significant surface preparation.Remember that the paste on the surface has the highest water / cement ratio and, therefore, will be the weakest part of the concrete.

Cure

Cure conditions should be clearly stated in any specification for concrete to accept non-permeable durable goods. The best results will be with a minimum 7 day wet cure provided by ponding, sprinkling or wet coverings. All curing compounds should be avoided. Under no conditions should the concrete be placed when temperatures are below 50°F (10°C) or above 90°F (32°C). Prior to application of any resinous coatings or toppings, calcium chloride tests should be performed to evaluate the rate of moisture vapor transmission of the slab. The resinous system manufacturer should be consulted concerning allowable moisture levels prior to product application.

Finishing

The Selection Process

Figure 5.7, lists the concerns and needs of plant engineers planning a floor renovation, based on a national poll. Additional reasons for flooring projects include: aesthetics, light reflectivity, impact, material, maintenance procedures and potential for future change in area usages.

HEAVY FORK LIFT TRAFFIC — The specified system must withstand high abrasion from rolling loads. Generally, thicker systems (1/8″) or greater are used to provide sufficient wear resistance and protect against impact when forks or the forklift load is dropped.

CLEANABILITY — Maintenance of clean surfaces is critical in certain areas. A delicate balance must be struck between cleanability and slip protection, especially in wet areas. In addition, selected systems should resist both the mechanical and chemical demands of the cleaning operation. Working closely with the specifier, manufacturer and installing contractor will help insure cleanable systems are installed. It is a good idea to have a sign off on submitted samples to create a standard of performance or, better yet, sign off on (or approve) a project mock up prior to installation of the entire area.

SLIP RESISTANCE — As detailed above, needs for cleanability and safety dictate required surface profile. Typically, for more aggressive requirements, aggregates are incorporated into the resinous floor system. The size, shape, and type of slip-resistant additive is determined by the environment the floor is exposed to. The degree to which these aggregates are covered or encapsulated impacts how aggressively they protect against slips and falls. Often overlooked, Slip resistance is an important system attribute to help insure worker safety. Accidents attributed to slips and falls cost employers millions annually in lost time and lawsuits.

HARSH CHEMICALS — Both process and cleaning chemicals present challenges to resinous protection systems. Temperature, length of exposure (time), concentration, maintenance routine, and potential for chemicals to mix with other chemicals are all necessary pieces of information. With this information, the material manufacturer can recommend the proper protective system.

HEAVY FOOT TRAFFIC — Foot traffic can be aggressive from an abrasion standpoint if abrasive dirt is present in an area. Thin mil coating systems (


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