Situation

On 27th June 2012, Australian Standard AS1884-2012 was endorsed which stipulated how concrete floors should be tested prior to application of floor coverings (e.g. carpet or vinyl). This revised standard would operate in Australia in conjunction with International Standard ASTM F2170-09 (Standard test method for determining relative humidity in concrete floor slabs).        

Relative Humidity in-situ probe test method

Information required in advance of testing include:-

  • Site map separating concrete pour areas;
  • Depth of concrete;
  • Size of concrete pour in square metres;
  • Is concrete floor on ground level (drying from top)or upper levels drying from top and bottom);

Minimum number of moisture points is three for the first 100sqm and one for each additional 100sqm or part thereof. Depth of hole is either 40% of total slab if drying from the top only or 20% of total slab if drying from top and bottom. Holes need to be in place for 72 hours to allow moisture equilibrium before Relative Humidity (RH) readings take place. Format of measuring RH and reporting is detailed and slab is considered sufficiently dry if the RH does not exceed 75%.

Challenge

Taking readings for new slabs is done as late as possible in order to allow the slab to dry. Consequently, a lot of building activity is occurring when holes are drilled. Hence, protecting the hole, which has a plastic sleeve inside with a round protruding cap at the top, over the minimum 72 hours required can result in damaged moisture points like the photos included.

Work activity

When drilling the hole, it needs to be numbered as per site map and for reporting purposes. After the plastic sleeve is inserted it is best to highlight this spot to help minimise damage over the next three days.

Three days later, measurements can be taken where again protection is required as sensors need to be inserted in the holes which can be as long as 1-2 hours if testing a large number of moisture points. Substantial information is required and reported per hole as per the Australian Standard / ASTM F2170-09 and any special request by the client.

Upon completion, report of results is formatted and sent to the client. Based upon such results, a level of water proofing may be required before the floor covering occurs. This particular job was a refurbishment where the RH readings varied between 74.8 to 83.0% on a pre-existing slab.

Insulated Hood method

This alternative test method is used to validate the sealed concrete surface is working and no moisture is penetrating through the barrier from the concrete slab underneath.