Construction materials: Plastic
0.0 / 5
- Created by: tarasmith99
- Created on: 19-05-19 18:16
Uses of polymers
pipes
surface coatings
membranes
adhesives
jointing compounds
roofing materials
claddings
thermal insulants
fibre- reinforced plastics
1 of 11
Types of polymerisation
Addition polymerisation: thermoplastics
- relative movement on heating- softens at 60-100 C and stiffens on cooling
- range from hard and rigid to soft and pliable but all subject to creep and have a low elastic modulus
- generally unsuitable for load bearing
- do not rot or corrode or absorb water
Condensation polymerisation: thermosetts
- cannot be softened by heat
- rigid and hard
- insoluble in organic materials
- do not rot or corrode or absorb water
- sunlight may fade colour
2 of 11
Modification of polymers
chemical
- replace H atoms to increase stiffness and strength
co-polymerisation
- two or more monomers eg high impact polystyrene
additives
- plasticisers- reduce brittleness
- fillers- colouur, economy, lower brittleness, heat and chemical resistance
3 of 11
Thermoplastics
polythene
- water tanks, pipes, damp proof courses, waterproofing and seperating membranes
PVC
- sewerage pipes, roofing sheets, cladding, wall and floor tiles, wire insulators
adhesives and binders
4 of 11
Thermosetts
mouldings
- decorative
adhesives
fibre- reinforced polymer materials
cellular products
5 of 11
Cellular forms
- full of holes that are either open or closed
- open cells tend to be flexible but closed cells are best as they float on water and absorb very little
- low to very low density: 16-640 kg/m3
- high strength:weight ratio
- modulus of elasticity 3-3.6 GPa
- good thermal insulation
examples
- expanded polystyrene
- boards, sheets, packaging, insulation
- polyurethane foam
- open cell: upholstery
- closed cell: rigid insulation panels
- foamed glass reinforced plastics
- polyester resin and glass used for timber replacement
- lightweight embankments
6 of 11
Glass fibre reinforced plastics
- made of glass fibres and resins
- used in facades, lightweight bridges, bridge repairs
- good durability, lightweight, good strength:weight ratio
- beware creep and thermal sensitivity
- short fibres in concrete
- polypropylene
- high impact resistance
- crack control
- used as facade units, precast concrete products, industrial floor slabs
- potential reation with alkalis in cement to produce expansive matrix
7 of 11
Polymer fibre composites
- rapid growing interest in composites in general
- most has been focused on fibre reinforced polymers
- fuelled by the need to improve durability, reduce labour costs, construction time and to improve safety
- Uk government launched two initiatives:
- innovative manufacturing initiative
- materials for better construction programme
- ACCIS at Bristol Uni has 4 (5) central themes
- multifunctional composites
- novel microstructures
- design
- analysis and failure
- intelligent structures
8 of 11
Polymer fibre composites 2
Building industry
- infill panels and cladding elements
Civil engineering industry
- structures made completely of advanced polymer composite materials
- frp-concrete beam construction
- internal reinforcement to concrete members
- external reinforcement for metallic and reinforced concrete structures
- replacement or degraded concrete bridge decks
- frp confinement of concrete columns
- bridge enclosures
- increase ductility for blast resistance
9 of 11
Polymer fibre composites 3
- reinforcement of a relatively low modulus polymer with a high modulus high strength fibre uses the platic flow of the polymer material under stress to transfer the load to the fibre
- the product is a two phase material
- the fibre is the primary phase and is well dispersed in and bonded by the weak secondary phase which is the polymer
10 of 11
Polymeric materials
- most polymer materials are carbon based, produced largely from gas, oil and raw materials
- there are routes to polymers from wood and other natural materials
- rarely used in pure form but usually are supplied in a variety of types and grades in which the base polymer is compunded with additives
- commonly mixed with fillers
11 of 11
Related discussions on The Student Room
- Understanding Durometers: A Guide to Hardness Measurement »
- Gcse dt 2023 »
- 5 reasons to study Architecture at Bradford »
- aqa dt theory exam materials »
- AQA GCSE Design and Technology Written Exam (8552/W) - 19th June 2023 [Exam Chat] »
- chemistry moles question »
- EPQ »
- Which is a better brand of laptop? »
- Any tips for wearing glasses? »
- Please mark my econ 25 mark essay »
Similar Civil Engineering resources:
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
Comments
No comments have yet been made