In the world of construction and civil engineering, concrete is the ubiquitous workhorse. However, the strength and durability of a hardened concrete structure are only as reliable as the testing methods used to verify them. Before a single cube or cylinder can be crushed in a compression testing machine, a critical, often overlooked, preparatory step must be standardized: the casting and curing of the test specimens. This process is governed by BS EN 12390-2:2019, "Testing hardened concrete – Part 2: Making and curing specimens for strength tests." This standard is not merely a procedural checklist; it is a fundamental document that ensures the repeatability, comparability, and legal defensibility of concrete strength data across Europe and beyond.
Scope and Purpose
BS EN 12390-2:2019 is part of the EN 12390 series, which superseded the older BS 1881 methods. Specifically, this part details the apparatus, procedures, and environmental conditions for producing test specimens (typically cubes or cylinders) from fresh concrete and for curing them until the point of testing. The standard’s primary objective is to eliminate variability introduced by poor specimen preparation. If specimens are made or stored incorrectly, the subsequent strength test will reflect the quality of the curing regime, not the inherent quality of the concrete. Therefore, this standard acts as a gatekeeper for accuracy in quality control and compliance testing.
Key Requirements and Technical Innovations
The 2019 version introduced clarifications and updates from its predecessor (2009). Key technical requirements include:
Mould Specifications: The standard mandates that moulds must be rigid, non-absorbent, and capable of retaining their shape. It provides precise dimensional tolerances (e.g., for 150 mm cubes, the tolerance is typically ±0.2 mm) and specifies that the internal surfaces must be smooth and free from defects. A significant emphasis is placed on the verification of mould dimensions, recognizing that worn or warped moulds produce non-standard specimens that yield inaccurate strengths.
Compaction of Fresh Concrete: To avoid voids and honeycombing, the concrete must be properly compacted within the mould. The standard describes two primary methods: internal vibration (needle vibrator) and manual compaction (tamping rod). Crucially, it specifies the size of the vibrator head, the duration of vibration, and the number of rod strokes for manual compaction, depending on the specimen size and concrete slump. This removes operator guesswork.
Initial Curing (Mould Storage): After casting, specimens must be protected from evaporation, shock, and extreme temperatures. For the first 24 hours (the initial curing period), the standard recommends storing the moulded specimens at a temperature of 20°C ± 5°C and near 100% relative humidity, often achieved by covering with plastic sheeting or damp mats.
Final Curing (After Demoulding): This is the most significant update in the 2019 edition. The standard distinguishes between two curing regimes:
Practical and Legal Importance
BS EN 12390-2:2019 has profound practical implications. For a concrete supplier, compliance means that test cubes taken from a truck load, if cured by the standard, will provide a true measure of that concrete’s potential strength. Disputes often arise when a contractor’s onsite-cured specimens (representing the structure) differ from the supplier’s standard-cured specimens (representing the mix design). The standard explicitly clarifies that standard-cured specimens are for compliance testing (verifying the mix), while optionally, parallel specimens may be cured under site conditions for acceptance testing.
Legally, the standard is a normative reference in the European concrete standard (EN 206) and UK Building Regulations. If a failure investigation occurs, the first question asked is always: "Were the specimens made and cured to BS EN 12390-2:2019?" Failure to adhere can render test results void and lead to contractual disputes, project delays, or unnecessary demolition.
Conclusion
BS EN 12390-2:2019 may not be as dramatic as the crushing of a concrete cube, but it is arguably more important. It provides the scientific and procedural discipline necessary to ensure that a strength number is trustworthy. By meticulously specifying how to make and cure test specimens, this standard protects all parties—supplier, contractor, engineer, and client—from the chaos of unverified results. In the precise language of a 32-page document, it upholds a simple engineering truth: you cannot test quality into a concrete specimen after it is cast; you must control its creation from the very first pour. bs en 12390-2:2019
BS EN 12390-2:2019 is the British and European standard that defines the methods for making and curing test specimens (such as cubes, cylinders, and prisms) used specifically for strength testing of hardened concrete. This standard is a critical component of quality assurance in construction, replacing the previous 2009 version to incorporate updated procedures for compaction, transport, and initial storage. 1. Scope and Fundamentals
The primary objective of BS EN 12390-2:2019 is to standardize the preparation of concrete samples so that strength results are reliable and comparable across different laboratories and projects. It covers: Preparation and filling of molds. Compaction techniques (mechanical and manual). Surface leveling and marking. Curing protocols to ensure optimal hydration. Transportation requirements for specimens. 2. Standardized Apparatus and Materials
To ensure consistency, the standard specifies the use of equipment conforming to BS EN 12390-1. Key tools include:
Molds: Must be clean and coated with a non-reactive release agent to prevent sticking.
Compacting Tools: These can include internal (poker) vibrators, vibrating tables, or manual compacting rods/bars. Trowels/Floats: Used for mandatory surface leveling. 3. Procedural Methodology Specimen Preparation and Filling
Concrete samples must be obtained following EN 12350-1 and thoroughly remixed before use. Molds are typically filled in multiple layers depending on the concrete's consistency; however, self-compacting concrete is filled in a single layer without additional vibration. Compaction
Each layer must be fully compacted immediately after placement:
Mechanical Vibration: Using a vibrating table or poker vibrator until air bubbles cease to emerge.
Hand Compaction: Using a rod or bar, typically tamping at least 25 times uniformly per layer for a 100mm cube.
Mallet Tapping: After each layer, the outside of the mold is tapped with a mallet to close voids and release trapped air. Surface Finishing and Identification
After the final layer is compacted, excess concrete is removed and the surface is leveled flush with the mold rim. Specimens must be clearly marked for traceability without damaging the fresh surface. 4. Curing and Storage Requirements
Curing is the most critical phase for strength development, providing necessary moisture and temperature for cement hydration. BS EN 12390-2:2019 Concrete Testing | PDF - Scribd
BS EN 12390-2:2019 Testing Hardened Concrete: Making and Curing Specimens for Strength Tests The Foundation of Reliable Concrete Testing: An Analysis
The BS EN 12390-2:2019 standard is a critical document for civil engineers, laboratory technicians, and construction professionals involved in concrete quality control. This European Standard specifies the methods for making and curing test specimens for strength tests on hardened concrete. Compliance with this standard ensures that concrete strength results are accurate, repeatable, and representative of the material's true potential. Understanding the Significance of the Standard
Concrete is a heterogeneous material, and its measured strength is highly sensitive to how it is handled in its plastic state and how it is treated during the early stages of hardening. BS EN 12390-2:2019 provides a rigorous framework to minimize variables during the sampling and preparation process. By standardizing the size of the molds, the compaction methods, and the temperature and humidity of the curing environment, the industry can compare results across different projects and regions with confidence. Scope and Application
This part of the EN 12390 series applies to specimens made from concrete with a maximum aggregate size of 40 mm or less. It covers the preparation of cubes, cylinders, and prisms. The standard is used both for specimens made in a laboratory setting and those made on-site to verify the quality of concrete being delivered to a structure. Essential Equipment Requirements
To adhere to the standard, specific equipment must be used. Molds must be made of a non-absorbent, rigid material that does not react with cement paste. They must be watertight and capable of maintaining their shape under the pressure of compaction. Common materials include steel, cast iron, and certain high-density plastics.
The standard also specifies the tools for compaction. Depending on the consistency of the concrete, this may include internal vibrators (poker vibrators), vibrating tables, or manual tamping rods. For manual compaction, the rod must be circular in cross-section, straight, and made of steel with a smooth finish. The Making of Test Specimens
The process begins with obtaining a representative sample of fresh concrete according to EN 12309-1. Once the sample is ready, the molds are prepared by applying a thin film of non-reactive release agent to the internal surfaces.
The concrete is placed in the molds in layers. The number of layers and the duration of vibration or number of tamps depend on the dimensions of the specimen and the workability of the mix. Over-vibration must be avoided as it can cause segregation, while under-compaction leads to voids that artificially lower the recorded strength. After compaction, the top surface is leveled using a trowel or float to create a smooth, flat finish. The Curing Process: A Critical Phase
Curing is perhaps the most vital step in the preparation of concrete specimens. BS EN 12390-2:2019 outlines strict parameters for both initial and long-term curing. Initial Curing
Specimens must remain in the molds for at least 16 hours but no longer than 3 days. During this time, they must be protected from shock, vibration, and dehydration. The temperature during this initial phase must be maintained between 20°C and 25°C in temperate climates, or higher in hot climates if specified. Covering the molds with plastic sheeting or wet burlap is a common practice to prevent moisture loss. Standard Curing
After removal from the molds (demolding), the specimens must be cured in water or in a mist room. If water curing is used, the specimens must be fully submerged in a tank. The water temperature must be maintained at a constant 20°C (± 2°C). If a mist room is used, the relative humidity must be kept above 95%. This controlled environment ensures that the hydration of the cement continues optimally, allowing the concrete to gain strength at a predictable rate. Marking and Documentation
Every specimen must be clearly and indelibly marked so that it can be traced back to its specific batch, location in the structure, and date of manufacture. Accurate record-keeping is a requirement of the standard, including details of the sampling procedure, the compaction method used, and the duration and conditions of the curing period. Differences Between Laboratory and Site Curing
While the standard primary focus is on "standard curing" to verify the potential strength of a mix design, it also acknowledges "site curing." Site-cured specimens are treated as closely as possible to the actual structure they represent. These are often used to determine when formwork can be safely removed or when post-tensioning can occur. However, site-cured results cannot be used for official compliance with the 28-day characteristic strength requirements unless specifically permitted. Conclusion
The BS EN 12390-2:2019 standard is a cornerstone of modern concrete technology. By following its detailed procedures for making and curing specimens, the construction industry ensures that the data used to make safety and structural decisions is robust and reliable. Whether you are a technician in a commercial lab or a site manager overseeing a major pour, a deep understanding of this standard is essential for maintaining the integrity of the built environment. Mould Specifications: The standard mandates that moulds must
BS EN 12390-2:2019 is the British and European standard that dictates the procedures for making and curing concrete specimens for strength testing. It is a critical document for ensuring that concrete samples (typically cubes or cylinders) are prepared consistently so that strength results are accurate and comparable. What This Standard Covers
The document outlines specific laboratory and field procedures to maintain the integrity of concrete samples from the moment they are cast until they are tested for hardened strength:
Preparation & Filling: Instructions for preparing moulds and the systematic filling process to avoid segregation.
Compaction: Standardized methods for compacting the concrete within the moulds using mechanical or manual tools to remove air pockets.
Surface Leveling & Marking: Procedures for finishing the top surface and clearly identifying each specimen for tracking.
Curing: Strict requirements for temperature and humidity—often involving water tanks or humidity chambers—to allow the concrete to gain strength properly before testing.
Transport: Guidelines for safely moving specimens from the site to the laboratory without causing internal damage. Why It’s Important
Standardization: It ensures that a 28-day strength test in one lab is directly comparable to a test in another.
Reliability: Improper curing (e.g., letting a specimen dry out too quickly) can lead to artificially low strength readings, potentially causing a project to fail inspection unnecessarily.
Safety: Adhering to these methods ensures that the concrete used in buildings and infrastructure truly meets the design's structural requirements. Key Resources BS EN 12390-2:2019 Concrete Testing | PDF - Scribd
The standard is rigorous in its details. Deviations from these specifications can render a test result invalid.
Title: Testing Hardened Concrete – Part 2: Making and Curing Specimens for Strength Tests
Adherence to BS EN 12390-2:2019 is vital for structural integrity and legal compliance.