The Codit Method

Compact Diagnostic Test (CoDiT) is a sequence of experimental steps (Sklodowski 2006a) which serves to gain of a maximum knowledge from the investigations microcores. Such a sequence of measurements is non-destructive from the viewpoint of the monument if microcores are drilled out of masonry during installation works.

Consecutive steps of the CoDiT are:

Step 1. Draw a line to permanently mark the reference coordinates of the material within the structure e.g the vertical plane crossing a hole to be drilled. Step 2. Measure the velocity of propagation of surface wave (Rayleigh wave) along the marked the line and perpendicularly to it. Step 3. Drill a hole with a core drill bit, preferably during installation works and take out a microcore. Step 4. Flatten the core base which resulted after its breaking off and copy the line mark (from Step 1) on it and on the cylindrical side surface of the core. Step 5. Measure the core dimensions and weigh the core.

Step 6. Record an image of the side wall of the core and analyse micro-cracks, pores and material inhomogeneities.

Step 7. Perform three-point bending test of the core in the plane marked. Two "half-cores" will come into being.

Step 8. Cut the half-cores to the desired length and measure the velocity of propagation of the longitudinal wave along the cores. Step 9. Perform uniaxial compression test using one half-core (see Step 7).

Step 10. Perform diametral compression test of the other half-core along the originally vertical plane (comp. Step 1 and Step 7).

Destructive tests of Steps 9 and 10 can be modified as necessary. This is especially recommended when the number of microcores available for testing is greater than the one required for basic measurements. In such

Figure 1. Unwrapped surface of the microcore specimen PW6 from the sample before weathering.

a case an uniaxial cyclic compression of one half-core and a creep test of the other might be of a special interest.

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