Civil Engineering Materials

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Civil Engineering Materials

• Department of Civil, Structural and Environmental
  Engineering
• Trinity College Dublin

Dr. Roger P. West (TCD) Mr. Peter Flynn (Arup)
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• Section A Concrete

• A1 Basic Materials

• A2 Fresh Concrete Properties

• A3 Hardened Concrete Properties

• A4 Concrete Mix Design

• A5 Reinforced Concrete

• A6 Pre-stressed Concrete

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• Section A.4 Concrete Mix Design

1. Mix Requirements
2. EN206 Concrete Specification
3. Trial Mixes
4. Cube Variability
5. Characteristic Strength
6. Standard Deviation Margin
7. Target Mean Strength
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• Section A.4 Concrete Mix Design

1. Mix Requirements
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• Section A.4 Concrete Mix Design

1. Mix Requirements
Essential Properties of Hardened Concrete

• Strength

• Durability

Other requirements

• Satisfactory workability

• Stiffening time

• Cohesiveness

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• Mix
• Requirements

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• Section A.4 Concrete Mix Design

1. Mix Requirements
Strength

• Defined by the Characteristic Compressive
  Strength

• Defined by the crushing strength of 150mm cubes
  when 28 days old.

• Strength below which not more than 5 of test
  results fall. Generally referred to as 28 day
  strength

• Concrete must be designed to have an average
  strength well in excess of the characteristic
  strength required.

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• Section A.4 Concrete Mix Design

1. Mix Requirements
Strength
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• Section A.4 Concrete Mix Design

1. Mix Requirements
Strength
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• Section A.4 Concrete Mix Design

1. Mix Design
Types of Mixes (BS5328 /ISEN206)

• Designed Mix
• Performance specified by purchaser
• Producer is responsible for the design mix
  proportions
• Must conform to ISEN206

• Prescribed Mix
• Mix Proportions are specified by purchaser

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• Section A.4 Concrete Mix Design

1. Mix Design
Types of Mixes (BS5328 / ISEN206)

• Standard Prescribed Mix
• Admixtures are not permitted
• Producer is responsible for the design mix
  proportions
• Must conform to ISEN206

• Designated Mix
• Wide-ranging concretes for almost every type of
  concrete construction
• Specifications as per ISEN206/BS8500
• Third Party QA accreditation No cube testing on
  site

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• Section A.4 Concrete Mix Design

1. Mix Design

• Empirical Approach

• All mix designs require a trial mix

• The proportions of which may need modification in
  the light of experience

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1. Standards