We have regularly been on site when a surface resistivity meter has been placed on the concrete factory floor and the reading indicates the floor is within the range to be classed as static dissipative. Static problem solved – yes?
Unfortunately not, bare concrete floors can exhibit anti static (dissipative or conductive) properties. Whilst a concrete floor has the tendency to avoid building up a static charge, it does nothing to dissipate an existing charge. A person walking across a concrete floor who is already charged will remain charged until they transfer that charge by touch – ouch! The concrete floor will not remove the charge or ground the person.
Moisture – the enemy of ESD floors
The measure of how anti static concrete is depends on many variables, the most significant of which is its permeability to moisture.
The higher the moisture content in the concrete floor, the higher the conductivity. Do you know the surface upon which the concrete floor has been laid? After hardening or curing, a concrete floor transmits the moisture and the temperature of the ground below it. This is why quite often a concrete floor feels very cold to the touch and you wouldn’t want to sit on it for any length of time.
Has a waterproof sub membrane been used in the construction of the building? Unless you are a builder or a very keen tenant you probably don’t know! The soil, weather outside, who is in charge of the heating control that day will all affect the floor reading. Concrete therefore has very unpredictable conductivity and can not be designated as an ESD Floor.
Is it worth taking the risk?
Quite frankly, no. If you have problems with static or are concerned about the effect static could have on your workplace it is not worth taking the risk of relying on an unpredictable concrete floor which will not remove static build up.
There are a variety of simple cost effective floor solutions to combat static, including ESD floor paints, which are easy to apply and maintain. A relatively small upfront investment is definitely worth the long term benefit.