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Cover of Specification and Use of Geopolymer Concrete in the Manufacture of Structural and Non-Structural Components: Experimental Work
Specification and Use of Geopolymer Concrete in the Manufacture of Structural and Non-Structural Components: Experimental Work
  • Publication no: AP-T329-17
  • ISBN: 978-1-925671-14-8
  • Published: 12 October 2017

This report details the experimental phase of an Austroads project to review the specifications and use of geopolymer concrete. The findings indicate that acceptable grades of structural geopolymer concrete can be made for field applications.

This phase of the project involved formulating and testing geopolymer recipes for their workability, setting time, strength development, mechanical behaviour, durability properties and abrasion resistance. The flexural and ductility behaviours of large reinforced geopolymer concrete beams were also compared to those of equivalent ordinary Portland cement (OPC) concrete. The results show that commercially available Australian fly ash and blast furnace slag materials are suitable for the manufacture of geopolymer concrete, using solid sodium metasilicate alkali activators.

Geopolymer concrete formulations were developed for casting under ambient conditions; they performed satisfactorily with respect to workability, setting time, drying shrinkage, strength development, mechanical properties, and durability properties. Fly ash/slag blends in the range of 60/40 and 40/60, including 50/50 fly ash/slag, performed particularly well, and exhibited superior performance with respect to drying shrinkage, sulfate resistance, chloride penetration and alkali-aggregate reaction (AAR) compared to OPC?based concretes. However, 100% slag?based geopolymers may be prone to AAR, at high alkali contents, and exhibited much larger volume of permeable voids (VPV) values than equivalent OPC concretes, although the high VPV values do not necessarily indicate high porosity, but are relate to hydrated phases in the geopolymer concrete.

The abrasion resistance of geopolymer concrete is slightly lower than the equivalent OPC concrete, but formulations can be improved by lowering the water content. The ultimate load capacity of large beams made with OPC and geopolymer concretes are very similar, but the ductility of geopolymer beams was lower than that of OPC concrete, arising from the higher bond strength between the geopolymer concrete and steel than between OPC concrete and steel.

This experimental work follows an extensive literature review, published as Austroads Technical Report AP-T318-16 and Austroads Research Report AP-R531-16.

  • Summary
  • 1. Introduction
  • 2. Scope of Experimental Work
  • 3. Experimental Work
    • 3.1. Materials
      • 3.1.1. Fly Ash
      • 3.1.2. Slag
      • 3.1.3. Cement
      • 3.1.4. Liquid Sodium Silicate
      • 3.1.5. Potassium Silicate
      • 3.1.6. Solid Sodium Meta-silicate
      • 3.1.7. Sodium Hydroxide
      • 3.1.8. Mixed Activator made from Sodium Silicate and Sodium Hydroxide Solution
      • 3.1.9. Potassium Hydroxide
      • 3.1.10. Sand
      • 3.1.11. Coarse Aggregate
      • 3.1.12. Water Reducer/Super-plasticiser
    • 3.2. Material Factors and Range of Utilisation
      • 3.2.1. Water to Geopolymer Solids Ratio
      • 3.2.2. Amount of Activator
    • 3.3. Method of Study
      • 3.3.1. Experimental Plan
      • 3.3.2. Mix Proportioning
    • 3.4. Tests
      • 3.4.1. Workability of Mortar
      • 3.4.2. Workability of Concrete
    • 3.5. Mixing Procedure
      • 3.5.1. Mixing of Mortar
      • 3.5.2. Mixing of Concrete
    • 3.6. Specimens
      • 3.6.1. Mortar Specimens
      • 3.6.2. Concrete Specimens
    • 3.7. Curing
  • 4. Tests and Results for Fly Ash-based Geopolymer
    • 4.1. Effect of Water Reducers on Mortar Workability
    • 4.2. Influence of Contents of Water, Sodium Silicate and Super-Plasticiser (SP) on Properties
      • 4.2.1. Mix1 and Mix11
      • 4.2.2. Mix2 and Mix3
      • 4.2.3. Mix4: Rapid Setting of Mortar with High Ratio of Alkali in the Activator
      • 4.2.4. Effect of Reduced Alkali Content in Activator and Initial Curing Temperature
      • 4.2.5. Summary of Effect of Alkali on Strength of Fly Ash Based Mortars
      • 4.2.6. Other Types of Activator: Mix6 and Mix7
    • 4.3. Comparison of Mortar and Concrete
  • 5. Fly Ash-Based Geopolymer Incorporating a Source of Calcium
    • 5.1. Preliminary Investigation
      • 5.1.1. Mix5 – Effect of Incorporation of Slag and Lime
  • 6. Discussion on Fly Ash-based Geopolymer Mixes
    • 6.1. Setting Behaviour of Mixes
    • 6.2. Effect of Activator on Workability of Geopolymer Concrete
    • 6.3. Effect of Water to Geo-solid Ratio on Strength
    • 6.4. Amount of Sodium Silicate
    • 6.5. Effect of Total Alkali in Geopolymer
    • 6.6. Other Types of Alkali Silicate
      • 6.6.1. Potassium Silicate
      • 6.6.2. Sodium Meta-silicate Pentahydrate
      • 6.6.3. Anhydrous Sodium Meta-silicate
    • 6.7. Mix Proportions of Geopolymer Concrete
  • 7. Preliminary Results for Slag-based Geopolymer
    • 7.1. Slag-based Geopolymer with Liquid Sodium Silicate (WG) Activator
    • 7.2. Slag-based Geopolymer with Solid Sodium Silicate Activator
      • 7.2.1. Mix12
    • 7.3. Further Investigation on Incorporation of Slag in Fly Ash-based Geopolymer
      • 7.3.1. Effect of (Activator/Binder) Ratio
      • 7.3.2. Effect of Elevated Temperature Curing on Strength
  • 8. Further Investigations on Slag-based Geopolymers
    • 8.1. Curing Parameters
      • 8.1.1. Experimental Work for Making and Curing Geopolymer Mortar
      • 8.1.2. Mix Designs for Geopolymer Mortar
    • 8.2. Strength Effect of Curing
      • 8.2.1. Anhydrous Sodium Meta-silicate with 100% Slag
      • 8.2.2. Liquid Alkali Activator with 100% Slag
      • 8.2.3. Geopolymer Based on Slag + Fly Ash Blends and Anhydrous Metasilicate
      • 8.2.4. Geopolymer Based on Slag + Fly Ash Blends and Liquid Activators
      • 8.2.5. Geopolymers made with Slag + Fly Ash at Different Compositions and Silica Moduli
    • 8.3. Ambient Temperature (23 C) Curing
    • 8.4. Wet and Dry Curing Effects
      • 8.4.1. Wet Curing (Fog Room at 23 C)
      • 8.4.2. Dry Curing (Controlled Environment at 23 C, 50% RH)
      • 8.4.3. Effect of Form of Activator on Setting Behaviour and Strength
      • 8.4.4. Effect of Super-plasticiser on Setting Behaviour and Strength
    • 8.5. Extraction of Soluble Alkali
  • 9. Rheological, Mineralogical, Chemical and Microstructural Characterisation of Geopolymers
    • 9.1. Hydration Heat-calorimetric Analysis
    • 9.2. Thermogravimetric Analysis
    • 9.3. Further Studies of Rheological Behaviour of Geopolymers
      • 9.3.1. Setting Time
      • 9.3.2. Effect of Activator Type on Workability
      • 9.3.3. Calorimetry Measurements
    • 9.4. X-ray Diffraction Analysis of Geopolymers
    • 9.5. Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
      • 9.5.1. 27Al NMR Spectroscopy
      • 9.5.2. 29Si MAS-NMR Spectroscopy
  • 10. Concrete Made with Geopolymer Binder
    • 10.1. Mixing Procedure
    • 10.2. Workability and Strength of the Various Geopolymer Concretes
    • 10.3. Early Age Strength of Hardened Geopolymer Concrete
    • 10.4. Longer Term Strength Development of Geopolymer Concretes
    • 10.5. Drying Shrinkage of Geopolymer Concrete
    • 10.6. Flexural Strength of Geopolymers
    • 10.7. Stress-strain Behaviour of Geopolymer Concrete
    • 10.8. Volume of Permeable Voids (VPV)
  • 11. Alkali Aggregate Reaction in Geopolymer Concrete
    • 11.1. Assessment of AAR Susceptibility of Geopolymer Concrete by the Accelerated Mortar Bar Test (AMBT) Method
      • 11.1.1. Accelerated Mortar Bar Test Method (ASTM C1260-14:2014; RMS T363:2012a or VicRoads RC 376.03:2016)
    • 11.2. Assessment of AAR Susceptibility of Geopolymer Concrete by the Concrete Prism Test (CPT) Method
      • 11.2.1. Expansion Measurement of Concrete Prisms
    • 11.3. Scanning Electron Microscopy (SEM) Examination of various Geopolymer Specimens Subjected to AAR Tests
    • 11.4. Study of AAR in Large Geopolymer Beams
      • 11.4.1. Results of Strain Measurement in Beams and Discussion
  • 12. Sulfate Attack
    • 12.1. Sulfate Resistance
      • 12.1.1. Length Change due to Sulfate Attack
      • 12.1.2. Compressive Strength Variation in Samples Immersed in Sulfate Solution
  • 13. Carbonation of Geopolymer Concrete
  • 14. Chloride Ingress and Steel Corrosion in Geopolymer Concrete
    • 14.1. Chloride Permeability of Geopolymer Concrete
      • 14.1.1. Sample Preparation for the Chloride Penetration Tests
      • 14.1.2. Rapid Chloride Penetration Test results
      • 14.1.3. Chloride Diffusion Test Results
    • 14.2. Electrochemical Properties of Steel Embedded in Geopolymer Concrete
      • 14.2.1. Specimen Preparation
      • 14.2.2. Half-cell Potential and Corrosion Rate Measurements
    • 14.3. Corrosion Rate of Steel Embedded in Chloride Contaminated Geopolymer Concrete
  • 15. Creep Behaviour of Geopolymer Concrete
  • 16. Abrasion Resistance of Geopolymer Concrete
    • 16.1. Specimens
    • 16.2. Abrasion Testing
    • 16.3. Abrasion Depth Measurement
  • 17. Performance of Large Reinforced Geopolymer Concrete Beams: Ductility Behaviour
    • 17.1. Manufacture of Beams
      • 17.1.1. Geometry and Reinforcement Configuration
    • 17.2. Results
      • 17.2.1. Properties of Plain Geopolymer Concrete
      • 17.2.2. Load-deflection Responses of the Beams
  • 18. Conclusions of Experimental Work
  • References
  • Appendix A Properties of Raw Materials
  • A.1 Sieve Analysis of Aggregates
  • A.1.1 14 mm Aggregate
  • A.1.2 10 mm Aggregate
  • A.1.3 Sand