Sample Collection

SITE SELECTION

Signs of degradation can be used as markers for sampling points. The following can be considered:

  1. Presence of cracks

  2. Spalling of concrete

  3. Other signs of distress

  4. Low physical strength values


Physical strength values can be determined prior to core extraction using different non-destructive tests.

PROTECTING THE STRUCTURE

Rebar scanners are used to determine the location, depth, and thickness of concrete reinforcements such as steel bars. This is vital to avoid damaging the structures and the sampling instrument during coring or drilling.


(learn more about non-destructive testing here)

DRILLING

The essential equipment in concrete drilling is the diamond drill. It comes with different sizes of coring bits allowing the team to collect concrete cores of different diameters. A pressurized water pump is used to avoid too much friction which could damage the sample and the equipment.


After finalizing the target points, a diamond drill is installed. If the location permits a stand is used to stabilize the drill and ensure its perpendicular orientation with respect to the target building member.

DOCUMENTATION

Right after extraction, photos of the samples are taken. Descriptions are immediately recorded in a sample collection form to avoid missing any details that could be relevant in the analysis. Important details include:

  1. sampling point & structure type

  2. top and bottom indicators

  3. condition of structure

  4. age of the building

  5. drilling time

  6. noticeable deteriorations

STORAGE

As soon as in-situ observations are made, the extracted cores should be sealed and stored properly. Cling wraps and ziplock bags can protect the samples to prevent exposure to air that may lead to carbonation and prevent fluids from drying out. Place necessary labels and store in a dry and cool place.


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