Chapter 22. Coring, drilling and sampling techniques

An obvious method to determine the distribution of moisture in a material or structure is to take a sample from the intended position and then determine the moisture content or state of moisture on that sample. Most of the measuring principles described in PART A are useful for measuring moisture on a sample but the result depends very much on the sampling technique that was used. Here the possibilities, limitations, errors and uncertainties with different sampling techniques are described. The techniques used to take a number of samples from a series of depths in a structure or a specimen are several. The key issues are three: a) taking the samples from the intended depths and documenting the actual depths, b) taking representative samples, if required, c) avoiding disturbing (drying) the samples as much as possible until the measurement. The main principles of taking a series of samples are 1. drilling a (cylindrical) core, taking a larger piece of the material or taking a whole specimen and split it into smaller samples from different depths, 2. drilling holes and take the drill dust as samples, 3. using hammer and chisel to take samples from a specific depth.