SIST EN 480-4:2005

Overview

SIST EN 480-4:2005 is a European Standard published by CEN that specifies a test method for determining the bleeding of concrete. Bleeding refers to the relative quantity of mixing water that rises to the surface of freshly mixed concrete after placement. This standard applies to concrete mixes with aggregates up to a maximum size of 50 mm. It is part of the EN 480 series, which addresses various test methods for admixtures used in concrete, mortar, and grout.

Understanding and controlling bleeding is essential to ensure concrete durability, quality, and performance. Excessive bleeding can lead to segregation, reduced strength, and surface defects impacting structural integrity.

Key Topics

• Scope and Applicability
  The standard defines a procedure for measuring the percentage of water bleeding from fresh concrete mixes containing aggregates up to 50 mm in diameter.

• Apparatus Requirements

  • Rigid, non-absorbent cylindrical vessel with smooth interior surfaces
  • Precision balance with at least 0.1% accuracy
  • Pipette or similar sampling device for collecting bleed water
  • Graduated measuring cylinder (100 ml capacity)
  • Steel tamper and flat rounded float for compaction and leveling
  • Stopwatch to time intervals during testing

• Test Procedure

  • Sample preparation involves filling the vessel with concrete in three layers, each compacted with 25 strokes using the tamper.
  • The concrete surface is leveled minimally using a steel float.
  • The vessel is maintained at a controlled temperature (20 ± 2 °C) and relative humidity (≥65%), covered with a lid to minimize evaporation.
  • Bleed water is collected with a pipette at precise intervals: every 10 minutes for the first 40 minutes, then every 30 minutes until bleeding stops.
  • Careful tilting of the vessel may be used before water removal to aid collection without disturbing the concrete.

• Calculation and Results
  Bleeding (B) is expressed as a percentage of the total mixing water by mass:
  [ B = \frac{m}{w \times m_s} \times 100 ]
  where:

  • m = mass of bleed water (g)
  • m_s = mass of concrete sample (g)
  • w = percentage of water content by mass in fresh concrete
    The test report records bleeding to the nearest 0.1% and includes details about the concrete mix, aggregate size, admixtures used, date, and test personnel.

Applications

SIST EN 480-4:2005 is crucial for:

• Quality Control in Concrete Production
  Ensuring the concrete mix design minimizes excessive bleeding, which can otherwise cause weakening and surface defects.

• Admixture Performance Evaluation
  Assessing how various chemical admixtures affect bleeding characteristics, helping manufacturers optimize formulations for specific performance criteria.

• Construction and Structural Engineering
  Supporting specifications and compliance checks for ready-mix concrete and specialized grout, particularly in projects requiring precise control of water content and durability.

• Research and Development
  Providing a standardized method for testing bleeding in new concrete materials and innovative admixture technologies.

Related Standards

The EN 480 series complements SIST EN 480-4:2005 by covering other important test methods for admixtures in concrete, mortar, and grout, including:

• EN 480-1: Reference concrete and reference mortar for testing
• EN 480-2: Determination of setting time
• EN 480-5: Determination of capillary absorption
• EN 480-6: Infrared analysis
• EN 480-8: Determination of conventional dry material content
• EN 480-10: Water soluble chloride content determination
• EN 480-11: Air void characteristics in hardened concrete
• EN 480-12: Alkali content of admixtures
• EN 480-13: Reference masonry mortar for testing mortar admixtures

Together, these standards provide comprehensive guidelines for assessing admixture effects, contributing to the production of durable, high-quality concrete with predictable performance characteristics.

By adhering to SIST EN 480-4:2005, engineers, quality controllers, and admixture manufacturers can reliably determine concrete bleeding, enhancing mix design accuracy, structural integrity, and long-term performance of concrete structures.