This code specifies the procedures for extracting, preparing, and testing cylindrical cores from hardened concrete to determine compressive strength. Engineers use this standard to assess the actual in-situ strength of concrete in existing structures, especially when standard cube test results fail to meet requirements or during structural audits.
Specifies procedures for drilling, preparation, and compressive strength testing of concrete cores from structures.
Quick Reference Values
Minimum core diameter>= 3 times nominal maximum aggregate size
Standard core diameters100 mm or 150 mm
Preferred Length/Diameter (L/D) ratio1.0 to 2.0
Tolerance on perpendicularity of prepared ends0.05 mm
Rate of loading during compression0.2 to 0.4 N/mm²/s
Key Formulas
f_core = P / A — Compressive strength of core (P = max load, A = cross-sectional area)
Practical Notes
Always scan the concrete using a rebar locator or GPR before drilling to avoid cutting through reinforcing steel, which weakens the structure and severely skews test results.
Ensure core ends are properly ground or capped perfectly perpendicular to the longitudinal axis; irregular ends cause stress concentrations and premature failure.
Cores containing embedded reinforcement should be avoided for compressive strength testing as they yield lower and less reliable results.