HIGH PERFORMANCE FLOORINGS

Flooring plays a very important role in manufacturing and certain service industries. Depending on the situation the demands on the floor can range from chemical, impact or abrasion resistance to capability to absorb thermal shock or dissipate static electrical charge. In clean room conditions, seamless floors are mandatory to prevent bacterial growth.

BASIC REQUIREMENTS OF THE RCC FLOOR:

Before any resin system can be applied to accentuate the performance of the RCC floor, it must be recognized that the floor should meet certain basic requirements:

• the concrete in the floor should have a compressive strength of at least 25N/mm².

• the concrete surface should be free of oils / greases and laitance – adequate scientific surface preparation is mandatory.

• a damp proof membrane should have been preferably installed below the floor slab to prevent any possibility of rising dampness.

• expansion and contraction / construction joints should be provided as per good practice.

Abrasion Resistance : When only abrasion is to be countered in order to prevent dust generation and wearing out of RC floors, at the floor concreting stage, addition of non – metallic or metallic hardness by a dry – shake – on system can improve abrasion resistance of a M25 control concrete by more than 200%.

Abrasion & Chemical Resistance :Floor coatings based on Epoxy or Polyurethane can provide chemical resistance abrasion resistance. Coatings are generally toppings in a thickness from 0.1mm to 0.5mm. these being thin coatings, re coatings will be required depending on usage. In many industrial situations these coatings are reapplied as part of annual maintenance. Use of these coatings also prevents oil spill absorption in concrete. The coated floors are seamless and generally very easy to clean. These coatings after the necessary surface preparation can be laid at 1000 m² per day and are available in a range of colours.

Abrasion, Chemical & Impact Resistance : It is possible to build some impact resistance on the concrete floor by providing thicker toppings which can range in thickness from 1.5mm to 10mm. Self Smoothing Toppings are available in a colour range and can provide good light reflectance and good working conditions. Resin screeds topped with sealer coatings are popular in heavy industries for providing a combination of abrasion, chemical and impact resistance in order to provide durable floors. Impact resistant resin screed floors obviate the need for long periods of costly plant downtime to restore floors.

As the size of electronic components decreases the level of complexity increases. The awareness of static electricity as an industrial hazard has prompted the electronics industry to investigate its causes. Small electrostatic discharge (ESD) may not cause any measurable change in device performance at the manufacturing stage, but the device could fail in the field.

A static control program includes a number of measures designed to collectively reduce the level of static electricity in designated working areas either by allowing charges to dissipate to ground or by reducing the level of charging in the first place. It can be seen that a static control program employs a number of measures, including protective wrist straps, conducting shoes, conducting bench tops and conducting floors.

In many industrial situations flooring plays a vital role in the reduction of electrostatic hazard. The simplest principle is that all personnel and vehicles on the floor should be earth potential, and therefore the electrical path from the body to earth must be complete. To achieve this, three requirements of the floor need to be met:

1. Flooring material should be sufficiently electrically conductive i.e. capable of charge dissipation for which a minimum resistance of 1000000 ohms is fairly widely accepted.

2. Conductivity should be independent of environmental conditions. Concrete for example, can have a resistivity of approximately 1000000 ohms at fairly high humidities, provided it has clean surface. However, its resistance may increase dramatically at low humidities. Conductive floor should have resistances, which do not vary with humidity.

The performance of the floor should remain constant with time. Surface paints, Vinyl sheet floor coverings, tiles etc. do not comply with this condition since they are susceptible to mechanical damage from forklift and other vehicles, and wear out leaving untreated bare spots. Epoxy resins provide the best matrix or binder since they give high mechanical strength, chemical resistance and a smooth cleanable surface.

The electrostatic charge travels through the topcoat (epoxy resin doped with conducting particles) and is dissipated to earth by the conductive undercoat. The latter is grounded by its contact with the concrete substrate. In case epoxy is laid on a completely insulating surface a small earthing connection can be made from the conductive undercoat to the factory earth circuit.

Concrete road, warring courses in bridges etc. are treated with bituminous overlay to prevent moisture / oil ingress and to absorb impact and prevent abrasion. Bitumens are not durable, and they yield to variations in temperature, wear and tear etc. Besides bitumen is not resistant to fuel and oil. The way is paved for corrosion of the embedded reinforcement. Ultimately, the concrete surface is exposed to the brunt of the traffic. Considering all the above, there is a requirement for a light weight topping that can offer high resistance to these abuses and act as an waterproofing. This results in superior performance coupled with Dead Load reduction benefit.

Pitch epoxy screed is based on modified epoxy resins, amine curing agents and chemically inert graded silica fillers for non - slip properties. The combination of pitch, modified epoxy resins with inert filler provides a hardwearing surface, with excellent resistance to chemicals, fuels and oil ingress.

Apart from the above mentioned benefits the system also offers complete waterproofing & corrosion protection to steel and concrete substrate. Because of its non – slip properties even when wet, it is excellent for industrial use in certain situations.

Floor Joints: Proper planning and installation of floor joints plays a vital role in determining service life of the floor. The following are the type of joints used.

• a. Construction joints : As the name implies this joint is necessitated due to limitations in construction methods.

• b. Contraction joints : This is the most important joint in any concrete floor construction. Concrete due to its inherent property to shrink as it hardens causes shrinkage stresses which increases gradually as concrete sets and gains strength. As the tension builds up it is initially resisted by the tensile strength of concrete and the reinforcement provided at the top (if any). Once the total tensile force at any section exceeds the tensile strength at that section, it will tear the concrete, thereby providing a random crack in a zig – zag fashion. This problem of random shrinkage cracks is solved by introducing dummy joints ensuring stress release only at this joint. Construction and Construction Joints can be coincided preferably.

• c. Expansion joints : These joints provide for expansion and contraction of the concrete floor due to temperature variations. They are provided at about 30m spacing and should coincide with similar joints in the super structure.

• d. Isolation joints : These joints are provided where the concrete floor meets permanent structural elements such as machine foundations, columns etc.

Each of the above joints need to be treated specially and filled with appropriate sealants depending on MAF (Movement Accommodation Factor) required and other floor performance requirements.

With each industry requiring tailor made floor system to suit the requirements, one must have a very good understanding of the behaviour of all materials available, to produce a workable industrial floor finish, starting from correctly laying the sub – grade soil, base floor concrete to applying the correct protective system required for the situation.