Core Extraction & Laboratory Testing

Core extraction is the definitive method for determining the actual material properties of existing concrete. TRSC extracts cylindrical core samples from structural elements using diamond-tipped coring equipment and submits them to NATA-certified laboratories for analysis. The results, compressive strength, density, chloride content, carbonation depth, and petrographic composition, provide the measured material data that underpins every structural calculation, durability assessment, and remediation design TRSC produces.

The decision to extract cores is never taken lightly. Coring creates a hole in the structure that must be repaired, and if poorly located, can damage reinforcement or services. TRSC uses GPR and Ferroscan scanning at every proposed core location to confirm safe clearance before drilling. Core locations are selected based on the investigation objectives, representative locations for strength assessment, worst-case locations for durability assessment, and specific locations where NDT results indicate anomalies requiring confirmation.

Compressive strength testing to AS 1012.9 provides the fundamental material property for structural capacity calculations. TRSC core results consistently demonstrate that actual concrete strength exceeds original design strength, often significantly, because concrete continues to hydrate and gain strength over decades of service. This finding has material consequences: at 12 Creek Street, measured compressive strengths substantially exceeded the assumed design strength, which directly increased the calculated residual capacity of the facade system.

Beyond compressive strength, core samples enable a range of durability tests that characterise the concrete's resistance to deterioration. Chloride profiling (powder drilling at incremental depths) determines how far chloride has penetrated and at what rate. Carbonation depth testing (phenolphthalein indicator on freshly broken core faces) shows the depth of the neutralised zone. Petrographic analysis (thin-section microscopy) reveals the internal condition of the concrete, aggregate quality, air void structure, evidence of alkali-silica reaction, and the condition of the cement matrix.