Glassfibre Reinforced Concrete: SPD processes/Techniques

  • ID: 4372272
  • Book
  • 224 Pages
  • Whittles Publishing
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The development of glassfibre reinforced concrete (GRC) in the 1960s [1-4] exploited an ancient and simple principle of converting naturally brittle materials into much tougher and therefore more useful ones through the incorporation of strong fibres, initially of plant origin. 

GRC is based on the same principle, and in the twenty-first century it is an already well-established construction material used all over the world. Basic constituents of GRC are very few, namely cement, water, fine aggregate and glass fibres.

However, the internal structure of the composite itself is as complex as that of the most advanced high-tech materials, such as composites used in the aerospace industry. Paradoxically, a high-performance material such as GRC can also be reliably produced using relatively simple and inexpensive processes.

The range of its applications is already very wide. In its basic form, it is used to produce simple items such as ornamental flowerpots; while in its hightech version, it is the preferred construction material for the production of large, thin-walled structural elements of very complex shapes. GRC is a cement-based composite strongly related to concrete.

However, in order to exploit its outstanding properties, substantial additional knowledge and understanding are required. Applications which utilise high-performance GRC do not require an excessively sophisticated and expensive production plant, but they do require a very strict production regime.

An adequate level of supervision is much closer to that used for the production of high-performance, polymer-based, fibre-reinforced composites than to the manufacture of ordinary precast reinforced concrete products.

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1 Introduction and Scope

2 Brief History of Development

3 Constituent Materials
3.1 Binders
3.2 Aggregates
3.3 Fibres
3.3.1 Composition and basic properties
3.3.2 Size, shape and length
3.3.3 Alkali resistance
3.4 Admixtures
3.4.1 Plasticisers and superplasticisers
3.4.2 Viscosity-modifying agents
3.4.3 Accelerators and retarders for setting/hardening
3.4.4 Titanium dioxide
3.4.5 Other admixtures
3.5 Polymers, pigments and additives/fillers
3.5.1 Polymers
3.5.2 Pigments
3.5.3 Microsilica
3.5.4 Hydraulic additives
3.6 Water

4 Manufacture
4.1 Batching and mixing
4.2 Production of GRC elements
4.2.1 Premix and casting
4.2.2 Simultaneous spray-up
4.2.3 Other production methods
4.3 Curing
4.4 Moulds and formwork
4.5 Surface finishes and treatments
4.6 Handling, transport, storage and repairs
4.7 Cutting and shaping

5 Composite Action
5.1 Internal microstructure
5.2 Fracture mechanisms
5.3 Influencing factors 
5.3.1 Mechanical properties of fibres
5.3.2 Mechanical properties of the matrix
5.3.3 Bond

6 Properties of GRC
6.1 Properties of fresh GRC
6.2 Properties of hardened GRC
6.2.1 Basic influencing factors and typical mix designs
6.2.2 Methods for assessment of performance 
6.3 Physical properties
6.3.1 Density
6.3.2 Permeability, water absorption and apparent porosity
6.3.3 Acoustic properties
6.3.4 Thermal properties
6.4 Mechanical properties
6.4.1 Modulus of elasticity
6.4.2 Flexural/bending strength
6.4.3 Tensile strength and Poisson’s ratio
6.4.4 Compressive strength
6.4.5 Transverse tensile and inter-laminar shear strength
6.5 Toughness and impact resistance
6.6 Durability
6.6.1 Wet/dry cycles
6.6.2 Freeze/thaw cycles
6.6.3 Fire resistance
6.6.4 Chemical, biological and other exposure
6.7 Volume (dimensional) changes
6.7.1 Effects of humidity: shrinkage/swelling
6.7.2 Creep and fatigue 
6.7.3 Thermal contraction/expansion
6.8 Self-cleaning
6.9 Environmental performance
6.9.1 Energy requirements
6.9.2 Environmental impact analysis
6.9.3 Active de-pollution of environment by eGRC
6.9.4 Recycling of GRC 

7. Structural Design
7.1 Principles
7.2 Typical structural elements
7.2.1 Single-skin sheet
7.2.2 Ribbed panels
7.2.3 Sandwich panels
7.2.4 Stud-frame system
7.3 Fixings
7.3.1 Basic functions and design principles
7.3.2 Types of fixings
7.3.3 Durability

8. Specification and Compliance
8.1 General guidance, grades and their selection
8.2 Production quality control and compliance
8.3 Sampling and frequency of tests
8.4 Testing
8.4.1 Content of glass fibres 
8.4.2 Grade
8.4.3 Bulk density, water absorption and apparent porosity 
8.4.4 Other tests 
8.5 Dimensional tolerances
8.6 Potential defects 
8.6.1 Uneven fibre content and distribution
8.6.2 Inadequate or excessive thickness
8.6.3 Excessive cracking and crazing
8.6.4 Porosity, insufficient compaction and surface defects
8.6.5 Excessive efflorescence
8.6.6 Ghosting
8.7 Repair and remedial actions 

9 Health and Safety

10 Summary of Benefits 

11 Applications 
11.1 Introduction 
11.2 Mature structures 
11.3 Civic/public buildings
11.4 Office and commercial buildings
11.5 Residential buildings
11.6 Religious structures
11.7 Art and recreation
11.8 Reconstruction/conservation of historic and contemporary buildings
11.9 Interior decoration and furniture
11.10 Architectural building components
11.11 Civil and environmental engineering

12 Standards

13 References

Appendix A: Calibration of GRC Spray Equipment
A.1 Bag test
A.1.1 Equipment
A.1.2 Method
A.1.3 Glass output
A.2 Bucket test
A.2.1 Equipment
A.2.2 Method
A.2.3 Slurry output
A.2.4 Calculated examples
A.2.5 Basic procedure
A.3 Mini-slump test: measuring flow of slurry
A.3.1 Equipment
A.3.2 Method
A.3.3 Notes

Appendix B: Determination of Glass Content of Uncured GRC
B.1 Scope
B.2 Definitions
B.3 Test specimen
B.4 Test procedure
B.5 Calculation and expression of results
B.6 Test report

Appendix C: Determination of Flexural Properties of GRC
C.1 Scope
C.2 Definitions
C.3 Apparatus
C.4 Test specimen
C.5 Number of test specimens
C.6 Procedure
C.6.1 Conditioning of test specimens
C.6.2 Testing procedure
C.7.1 Limit of proportionality
C.7.2 Modulus of rupture
C.7.3 Directionality ratio
C.7 Calculation and expression of results
C.8 Test Report

Appendix D: Determination of the Dry and Wet Bulk Density, Water Absorption and Apparent Porosity of GRC
D.1 Scope
D.2 Apparatus
D.3 Test specimen
D.4 Test procedure
D.5 Calculation and expression of results
D.6 Test report

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