Core Compressive Strength Test
(In-Situ Concrete Strength)

Extraction of cylindrical concrete cores from hardened structures and testing their compressive strength to determine the actual in-situ concrete strength — the definitive method for strength verification.

Overview

What is the Core Compressive Strength Test?

The Core Compressive Strength Test involves drilling cylindrical core samples from hardened concrete structures using a diamond-tipped core drill, trimming and capping the cores, and testing their compressive strength in a calibrated compression testing machine. The results represent the actual in-situ strength of the concrete at that location.

Conducted as per IS 516, ASTM C42 and BS EN 12504-1, core testing is the most reliable method for assessing concrete strength when cube results are missing, below acceptance criteria or when in-situ strength verification is required. Global Lab extracts, prepares and tests cores in our NABL-accredited laboratory.

Definitive Strength Data

Core compressive strength is the most reliable measure of actual in-situ concrete strength.

Replaces Missing Cube Results

Accepted substitute when cube test records are missing or disputed.

L/D Ratio Correction

Strength results corrected for length/diameter ratio per IS 516 / ASTM C42.

NABL Certified Reports

All core extraction and testing results on NABL-accredited letterhead.

Structural Assessment Use

Results directly used in structural capacity calculations for existing buildings.

All Structure Types

Cores extracted from slabs, columns, beams, walls and foundation elements.

Test in Action

Core Compressive Strength Test — Site Images

Test on Site

Core Preparation in Laboratory

Compression Testing of Concrete Core

Test Procedure

How the Core Compressive Strength Test is Conducted

1

Core Location Selection

Core locations are selected to represent the structure — avoiding rebar (confirmed by covermeter), construction joints and damaged zones.
2

Diamond Core Drilling

A 100mm (or 150mm) diamond-tipped core drill is used to extract cores to a minimum length of 150mm (or 2× diameter).
3

Core Preparation

Cores are trimmed to achieve L/D ratio of 2:1, ends are ground flat and parallel, and any rebar inclusions are noted.
4

Compression Testing

Prepared cores are tested in a NABL-calibrated compression testing machine at a standard loading rate per IS 516.
5

Strength Calculation & Reporting

Compressive strength is calculated and corrected for L/D ratio per IS 516 Table 2. Comparison with design strength made. NABL report issued.

Standards & Specifications

Applicable Test Standards

Standard	Title	Scope	Type
IS 516	Methods of Tests for Strength of Concrete	Compressive Strength	Indian Standard
ASTM C42	Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete	Core Test	ASTM
BS EN 12504-1	Testing Concrete in Structures — Cored Specimens — Taking, Examining and Testing in Compression	Core Strength	British Standard
IS 456:2000	Plain and Reinforced Concrete — Code of Practice (Core Acceptance Criteria)	Acceptance Criteria	Indian Standard

Applications

Where is the CAPO Test Used?

Verification of in-situ concrete strength when cube results are below acceptance criteria

Structural assessment of existing buildings for renovation, extension or change of use

Investigation of structures affected by fire, flood, chemical attack or construction defects

As-built quality verification for government and infrastructure projects

Forensic investigation following structural failure or construction dispute

Pre-demolition assessment for material reclamation and load capacity verification

Why Choose Global Lab

Our Advantages

NABL Accredited ReportsLegally valid strength certificates accepted by all structural engineers and authorities.

Complete Core ServiceSite extraction, laboratory preparation, compression testing and report — all in one.

Autovity Digital ReportsAccess core test results and load-deformation curves digitally.

Experienced Structural EngineersResults interpreted with written structural assessment recommendations.

Pan-India CoverageCore drilling teams and NABL lab testing across 7 locations in India.

Combined AssessmentCore strength + UPV + Rebound Hammer for complete structural evaluation.

Core Compressive Strength Test(In-Situ Concrete Strength)