When a core is tested for strength, how should it be drilled?

When testing a core for strength, the method of drilling is crucial to ensure that the results accurately reflect the concrete's properties. Drilling perpendicular to the surface allows for a consistent cross-section of the concrete to be tested, which aligns with standardized testing procedures. This orientation minimizes any potential biases in strength readings that could arise from the core being drilled at an angle.

Additionally, drilling at least 6 inches away from formed joints is important because these joints can create weaknesses or variations in the concrete's structure. Forming joints often characterize areas where there may be differences in curing, density, or even potential voids. By positioning the core drilling away from these joints, the core sample is more likely to represent the concrete's overall strength and quality, providing a more accurate measurement.

The importance of this method is underscored by the fact that other drilling angles or directions may introduce variability or inaccurately reflect the concrete's performance under load. Therefore, the established practice of perpendicular drilling, combined with maintaining an appropriate distance from joints, is essential for obtaining representative and reliable strength test results.