Polymers, Bituminous Materials and Composites

Introduction and context

Construction materials are increasingly selected not only for compressive strength, but also for durability, flexibility, impermeability, chemical resistance, low weight, constructability and life-cycle performance. Polymers, bituminous materials and composites are important because they provide combinations of properties that are difficult to obtain from traditional cementitious and metallic materials.

A polymer is a material made of very large molecules formed by joining smaller molecules called monomers. Bituminous materials are viscous, hydrocarbon-based binders, chiefly asphalt and bitumen, used for waterproofing, paving and bonding. A composite is an engineered material formed by combining two or more distinct constituents so that the resulting material has useful properties not available from either constituent alone.

These materials are not interchangeable. A thermoplastic may be reheated and reshaped, whereas a thermoset normally cannot be remelted after curing. An elastomer can undergo large reversible deformation, while a fiber-reinforced polymer (FRP) is designed primarily for high stiffness and strength. Asphalt must be selected according to temperature, loading, aging and moisture conditions. Sound construction practice therefore requires understanding manufacture, structure, properties, degradation, compatibility and application together.

Learning objectives

After studying this chapter, a student should be able to:

1. Explain the molecular and structural basis of polymer behavior.
2. Distinguish thermoplastics, thermosets and elastomers.
3. Describe the manufacture and construction uses of common polymers.
4. Explain asphalt composition, grading, production and pavement behavior.
5. Describe the constituents, mechanics and applications of FRP and engineered composites.
6. Evaluate degradation mechanisms and material compatibility.
7. Select appropriate materials for practical construction situations.
8. Recognize environmental, safety, quality-control and life-cycle considerations.

1. Polymer structure and classification

1.1 Molecular structure

Polymer chains may be linear, branched or cross-linked. Chain length, branching, chemical groups, crystallinity and cross-link density influence stiffness, strength, ductility, softening temperature and chemical resistance.

In a linear polymer, molecules are long chains with limited permanent connections between chains. Branches interrupt close packing and generally reduce density and crystallinity. Cross-links connect chains into a three-dimensional network. Increasing cross-linking usually increases dimensional stability and resistance to flow, but decreases the ability to melt and reshape the material.

Many construction polymers are viscoelastic. Their response depends on both stress and time. Under a sustained load, a polymer may creep; under a sustained deformation, it may relax its stress. Temperature has a strong effect: increasing temperature generally increases molecular mobility and reduces stiffness.

Two useful transition concepts are the glass-transition temperature, T₍g₎, and melting temperature, T₍m₎. Below T₍g₎, an amorphous polymer is relatively glassy and stiff; above T₍g₎, it becomes more rubbery. A crystalline thermoplastic has an ordered phase that melts over a temperature range near T₍m₎. T₍g₎ is not the same as a melting point and is especially important for elastomers and amorphous plastics.

1.2 Polymerization and manufacture

Addition polymerization joins unsaturated monomers without producing a small-molecule by-product. Polyethylene, polypropylene, polyvinyl chloride and polystyrene are common examples. Condensation polymerization joins molecules while often releasing water, alcohol or another small molecule; many polyesters, polyamides and phenolic resins are produced in this way.

Industrial manufacture commonly includes monomer preparation, polymerization, separation, compounding, shaping and finishing. Additives may include plasticizers, stabilizers, pigments, flame retardants, fillers, lubricants, impact modifiers and ultraviolet absorbers. Construction products are formed by extrusion, injection moulding, compression moulding, calendaring, pultrusion, rotational moulding, casting or coating.

The manufacturing process strongly affects performance. Extrusion can produce pipes and profiles with continuous length. Injection moulding is suitable for complex fittings. Pultrusion produces constant-section FRP profiles with continuous aligned fibers. Compression moulding is widely used for cured thermoset components.

2. Thermoplastics, thermosets and elastomers

2.1 Thermoplastics

Thermoplastics soften when heated and harden when cooled, provided that heating does not cause excessive chemical degradation. The process is substantially reversible, allowing many thermoplastics to be reshaped and, in principle, recycled.

Important construction thermoplastics include:

Thermoplastics are useful where low mass, corrosion resistance, waterproofing and rapid installation are valuable. Their limitations include thermal expansion, creep under sustained load, combustible behavior for some grades, and loss of stiffness at elevated temperature.

2.2 Thermosets

Thermosetting polymers are shaped and cured through an irreversible chemical reaction. During curing, cross-links form a rigid network. Once fully cured, the material does not melt into a processable liquid; excessive heating causes decomposition or charring.

Common thermosets include epoxy, polyester, vinyl ester, phenolic resin, polyurethane systems and melamine-formaldehyde. Epoxy resins are widely used in structural adhesives, protective coatings, crack injection and FRP matrices because of their adhesion, low shrinkage and chemical resistance. Polyester resins are economical and common in molded FRP products. Phenolic materials have useful fire and smoke characteristics in selected applications.

Curing depends on resin, hardener or catalyst, temperature, mix ratio, moisture and surface condition. An incorrect resin-to-hardener ratio can leave unreacted components, reduce strength or produce a tacky surface. Site personnel must follow the product data sheet rather than estimating proportions.

2.3 Elastomers

Elastomers are polymers capable of large, mostly recoverable strains. Their chains are flexible and lightly cross-linked or physically constrained. Examples include natural rubber, styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), neoprene and silicone rubber.

Construction applications include joint seals, gaskets, waterproofing membranes, expansion-joint systems, vibration isolators and modified asphalt binders. EPDM is valued for weather and ozone resistance; silicone performs well over a broad temperature range; neoprene offers useful weathering and oil resistance; SBR is common in sealants and asphalt modification.

Elastomer performance depends on strain amplitude, frequency, temperature, aging and permanent set. A seal must remain compatible with joint movement and must maintain adhesion to the substrate. A sealant that is chemically durable but too stiff for the expected movement may fail through cohesive rupture or loss of adhesion.

2.4 Comparison

3. Properties, degradation and compatibility of polymers

3.1 Mechanical and physical properties

Polymer strength is influenced by molecular orientation, crystallinity, strain rate and temperature. A rapid load may produce a stronger apparent response than a slowly applied load because chains have less time to rearrange. This is why a product specification must identify test method, temperature, loading rate and conditioning.

Creep is progressive deformation under sustained stress. For a simple linear-elastic material, deformation is often idealized as proportional to stress. For polymers, this approximation may be acceptable only over a limited stress, time and temperature range. Long-term design should use creep data or appropriate reduction factors.

Thermal expansion is often much greater than that of concrete, masonry or steel. If a polymer component is restrained, temperature changes can create significant interface stresses. Detailing may require movement joints, slotted connections or flexible sealants.

3.2 Degradation mechanisms

Important degradation mechanisms include:

• Ultraviolet degradation: radiation breaks chemical bonds and may cause chalking, embrittlement, discoloration and loss of strength.
• Thermal oxidation: heat and oxygen alter polymer chains, producing hardening, softening or cracking.
• Moisture and hydrolysis: water can swell some polymers or break susceptible chemical bonds.
• Chemical attack: acids, alkalis, solvents, oils and plasticizers may cause dissolution, swelling or stress cracking.
• Biological attack: selected polymers and additives may be affected by fungi, bacteria or insects.
• Fatigue: repeated loading can initiate and propagate cracks.
• Creep and stress relaxation: sustained load or imposed strain changes dimensions and contact pressure.
• Fire: polymers may soften, ignite, release smoke or produce toxic combustion products, depending on composition.

Protection may involve UV stabilizers, protective coatings, proper drainage, compatible sealants, thermal isolation, fire-rated assemblies and inspection. A coating is not a substitute for selecting a chemically suitable polymer.

3.3 Compatibility

Compatibility is the ability of materials in contact to coexist without unacceptable physical, chemical or mechanical damage. It includes:

1. Chemical compatibility: no harmful reaction, extraction or swelling.
2. Mechanical compatibility: similar movement, stiffness and load-transfer requirements.
3. Thermal compatibility: acceptable response to temperature variation.
4. Moisture compatibility: no trapped water or vapor-driven deterioration.
5. Adhesive compatibility: adequate wetting, adhesion and cohesive strength.

For example, a bituminous membrane may be damaged by a solvent-containing adhesive, and a plasticizer may migrate from a flexible PVC product into an incompatible sealant. Compatibility should be checked using manufacturer data, standards and, where necessary, laboratory testing.

4. Bituminous materials and asphalt

4.1 Terminology and composition

Bitumen is a viscous, adhesive, hydrocarbon-based material obtained mainly from petroleum refining, although natural sources and recycled materials also exist. Asphalt commonly refers to a mixture of mineral aggregate and bituminous binder used in pavements; in some regions, asphalt and bitumen are used less precisely as near-synonyms. In technical writing, the distinction should be stated.

Bitumen contains families of compounds often described operationally as saturates, aromatics, resins and asphaltenes. The balance between these fractions affects viscosity, adhesion, temperature sensitivity and aging. Aggregate provides most of the load-carrying skeleton in asphalt concrete, while binder coats particles, provides cohesion and accommodates some movement.

4.2 Production and grading

Refinery processes may include atmospheric and vacuum distillation, air blowing, solvent processing and modification. Paving binders may be graded by penetration, viscosity or performance-related systems. Polymer-modified bitumen incorporates polymers such as SBS to improve elasticity, high-temperature resistance or fatigue performance.

Asphalt mixtures are manufactured by drying and heating aggregate, blending it with hot binder, transporting it, placing it and compacting it. Warm-mix technologies reduce production temperature using additives, foaming or process changes. Cold-mix and emulsion systems use water-based or chemically stabilized forms where appropriate.

4.3 Behavior in pavements and waterproofing

Asphalt is temperature-sensitive and viscoelastic. At high temperature or slow loading, it may flow and contribute to rutting. At low temperature or rapid cooling, it may become stiff and crack. Repeated loading can cause fatigue cracking. Moisture can weaken the aggregate-binder bond, a process commonly called stripping.

The principal pavement distress mechanisms are:

• rutting from permanent deformation;
• fatigue or bottom-up cracking from repeated tensile strain;
• thermal cracking from contraction and low-temperature brittleness;
• ravelling from loss of aggregate particles;
• oxidation and hardening;
• potholes and localized moisture damage.

In roofing and waterproofing, bituminous membranes rely on continuity, adequate laps, sound substrates and protection from puncture and ultraviolet exposure. Torch-applied systems require strict fire control; self-adhered systems require suitable temperature and surface preparation.

4.4 Asphalt quality and placement

Quality control includes binder certification, aggregate grading, moisture control, mixing temperature, delivery time, layer thickness, compaction and joint construction. The exact acceptance criteria depend on the governing road or building specification. Overheating may accelerate aging and produce emissions; insufficient compaction may leave excessive air voids and allow water ingress.

A simplified conceptual relationship for air-void content is:

where Vₐ is air-void content in percent, Gₘᵦ is the bulk specific gravity of the compacted mixture, and Gₘₘ is the maximum theoretical specific gravity with no air voids. Both specific gravities are dimensionless and must be determined using compatible test procedures. The relationship assumes that the mixture is represented by these measured volumes and is used in asphalt mixture control, not as a complete prediction of pavement performance.

4.5 Recycled and bio-based binders

Reclaimed asphalt pavement can conserve aggregate and binder, but its aged binder may increase stiffness and cracking risk. Rejuvenators may restore some flexibility, although their long-term effectiveness must be demonstrated. Bio-based binders, recycled polymers and lower-temperature technologies are active development areas. Environmental performance must be assessed over the entire life cycle rather than by production energy alone.

5. Fiber-reinforced polymers

5.1 Constituents and manufacture

An FRP consists primarily of reinforcing fibers embedded in a polymer matrix. Glass fibers are economical and widely used; carbon fibers provide high stiffness and strength at low mass; aramid fibers provide high tensile performance and impact resistance in selected applications. The matrix may be epoxy, polyester, vinyl ester or another resin.

The matrix transfers stress between fibers, protects them from abrasion and environmental exposure, and determines much of the laminate’s resistance to moisture and chemicals. Fibers carry most of the load along their direction. Manufacturing methods include hand lay-up, vacuum infusion, resin transfer moulding, filament winding, pultrusion and automated placement.

5.2 Anisotropy and mechanics

FRP is generally anisotropic. Its properties differ along the fiber direction and transverse to it. A unidirectional carbon laminate may be extremely strong longitudinally but comparatively weak in the transverse direction. Designers must therefore specify fiber orientation, stacking sequence, thickness, connection details and environmental reduction factors.

For a continuous unidirectional composite loaded parallel to the fibers, a simplified rule of mixtures for longitudinal elastic modulus is:

where Eₗ is the longitudinal composite modulus, E_f and E_m are the fiber and matrix moduli, and V_f and V_m are their volume fractions, with V_f + V_m = 1. This idealized equation assumes aligned continuous fibers, uniform bonding, elastic response and load parallel to the fibers. It does not predict transverse properties, laminate failure or defects.

For example, if a unidirectional laminate contains 60% fiber by volume, with E_f = 70 GPa and E_m = 3 GPa:

Eₗ = (0.60 × 70) + (0.40 × 3) = 42.0 + 1.2 = 43.2 GPa.

The value is an ideal estimate, not a design strength. Voids, waviness, imperfect wet-out, fiber misalignment and degradation reduce actual performance.

5.3 Construction applications

FRP is used for strengthening beams, slabs, columns and masonry; corrosion-resistant reinforcement; bridge decks; pultruded handrails and gratings; tanks; pipes; façade components; and seismic retrofit. Externally bonded carbon-FRP strips can increase flexural or shear capacity, while glass-FRP bars can replace steel where corrosion resistance is critical.

Limitations include poor performance in fire without protection, debonding from inadequately prepared concrete, brittle failure, ultraviolet exposure, galvanic interaction between carbon and metals in wet conditions, and uncertain behavior under sustained loads. FRP strengthening should be designed according to a recognized structural standard and verified for substrate condition, anchorage, environmental exposure and fire resistance.

6. Engineered composites beyond FRP

Engineered composites include concrete, asphalt mixtures, fiber-cement products, laminated timber, sandwich panels, polymer concrete, wood-plastic composites and geopolymer-based systems. A composite may contain a continuous matrix and dispersed reinforcement, or layered constituents with different functions.

A sandwich panel uses strong, thin faces separated by a lightweight core. The faces resist bending stresses while the core resists shear and maintains separation. This produces high bending stiffness at low mass, but face wrinkling, core crushing, moisture ingress and edge detailing must be considered.

Fiber-cement products combine cementitious matrix, cellulose or mineral fibers and process control to improve crack resistance and handling. Polymer concrete replaces some or all cement binder with polymer resin and can provide rapid curing and chemical resistance, although cost, fire performance and thermal compatibility may be limiting.

The quality of a composite depends on the interface. Poor bonding, voids, delamination, inadequate impregnation, moisture-sensitive constituents or differential movement can cause premature failure even when each constituent is individually strong.

7. Selection framework for construction practice

Material selection should proceed from service requirements rather than from material popularity. The following sequence is useful:

1. Define loads, movement, temperature, moisture, chemicals, fire exposure and design life.
2. Identify the required function: barrier, seal, binder, reinforcement, insulation, cladding or structural member.
3. Compare strength, stiffness, ductility, creep, fatigue, permeability, thermal behavior and durability.
4. Check compatibility with adjacent materials, adhesives, coatings and installation processes.
5. Review manufacture, transport, storage, site handling and quality control.
6. Consider repairability, recyclability, disposal, worker safety and life-cycle cost.
7. Confirm compliance with applicable codes, standards and manufacturer instructions.
8. Specify inspection, testing and acceptance criteria.

A low initial cost does not guarantee economic value. Life-cycle assessment should include material production, transportation, installation, maintenance, replacement, energy use and end-of-life treatment. Designers should avoid unsupported claims such as “maintenance-free” or “fully recyclable” unless boundaries and evidence are clearly stated.

Applied case: illustrative rehabilitation of a corroding parking structure

Background

An illustrative four-level reinforced-concrete parking structure is exposed to de-icing salts. Chloride-induced corrosion has caused cracking and local spalling in beams and slabs. The owner requires a repair with minimal closure time and expects at least twenty years of service.

Problem

A repair must restore concrete cover and structural capacity while reducing future chloride ingress. Alternatives include conventional concrete repair with a protective coating, replacement of selected reinforcement, a cementitious overlay, or an FRP strengthening system combined with corrosion protection.

Analysis

A site investigation identifies delaminated concrete, chloride concentration, reinforcement loss, moisture conditions, crack widths and load demands. Sound concrete is tested for tensile pull-off strength because an externally bonded FRP system depends on substrate integrity. The design team also checks fire exposure, ultraviolet exposure, vehicle impact, drainage and compatibility between primer, epoxy and protective coating.

FRP is attractive because it is lightweight, rapidly installed and resistant to chloride corrosion. However, it cannot simply cover unsound concrete. Delaminated material must be removed, reinforcement treated or replaced where necessary, and the surface repaired. The selected resin must be compatible with the moisture condition and service temperature. Fire protection may be required because an unprotected polymer matrix can soften or burn.

Approach and solution

The illustrative solution consists of concrete removal to sound material, reinforcement cleaning and localized replacement, patch repair, crack treatment, installation of externally bonded carbon-FRP strips for deficient beams, and a compatible protective coating. Drainage defects are corrected so that the repair is not continually exposed to standing salt water. Pull-off tests and visual inspection verify surface preparation; fiber orientation and bond length are checked during installation.

Outcome

The intervention reduces structural risk and closure time compared with extensive section replacement. Its success depends on controlling water and chlorides, not merely installing FRP. A maintenance plan includes periodic inspection for debonding, coating deterioration, cracking, drainage blockage and new corrosion symptoms.

Learning points

The case demonstrates that material selection is a system decision. FRP does not replace diagnosis, substrate repair, fire assessment or moisture control. Polymer products provide high performance only when design, preparation, installation and inspection are integrated.

Safety, regulation and sustainability

Polymer and bituminous work may involve volatile organic compounds, skin sensitizers, hot materials, solvents, dust, fumes and fire hazards. Safety controls include ventilation, gloves selected for the chemical, eye protection, respiratory protection where required, hot-work permits, ignition control, safe storage and access to safety data sheets. Workers must be trained in resin mixing and emergency response.

Regulatory requirements vary by jurisdiction but commonly address structural design, fire classification, drinking-water contact, emissions, waste, worker exposure and pavement performance. Compliance must be established through recognized standards and project specifications rather than informal product comparisons.

Sustainability requires balanced judgment. Thermoplastics may be recyclable but contamination and mixed compositions can prevent effective recovery. Thermosets and composite laminates are difficult to remelt, although mechanical recycling, pyrolysis and reuse pathways are developing. Long service life, low maintenance, reduced transport weight and corrosion resistance may offset challenges in manufacture or disposal. Environmental claims should use transparent life-cycle boundaries.

Contemporary developments and best practice

Current developments include recycled and bio-derived polymers, self-healing asphalt concepts, warm-mix asphalt, basalt and natural-fiber composites, digitally monitored FRP strengthening, automated composite manufacture and sensor-integrated materials. Artificial intelligence can assist inspection by identifying cracks, debonding indicators or pavement distress in images, but its output requires calibrated data, human review and documented uncertainty. AI should support—not replace—engineering judgment and code-based verification.

Best practice is to:

• select materials by exposure and service requirement;
• use certified products and compatible systems;
• verify substrate condition before bonding or coating;
• control resin ratio, temperature, moisture and cure;
• account for creep, fatigue, thermal movement and fire;
• protect polymers and bitumen from avoidable environmental exposure;
• document batch numbers, installation conditions and test results;
• design for inspection, repair and eventual recovery;
• treat manufacturer instructions as part of the installation specification.

Chapter Summary

Polymers are long-chain materials whose behavior depends on chain structure, crystallinity, cross-linking, temperature and time. Thermoplastics can generally be reheated and reshaped; thermosets form irreversible networks; elastomers accommodate large recoverable movements. Their construction performance is governed by creep, thermal expansion, chemical exposure, ultraviolet radiation, moisture, fire and compatibility with adjacent materials.

Bitumen is a hydrocarbon binder, while asphalt is commonly an aggregate-binder mixture. Asphalt is viscoelastic and temperature-sensitive, so pavements must be designed and constructed against rutting, fatigue, thermal cracking, moisture damage and aging. Fiber-reinforced polymers combine fibers and a polymer matrix to provide high strength or stiffness at low mass, but they are anisotropic and sensitive to bonding, fire, defects and environmental conditions. Engineered composites rely on effective interfaces and coordinated constituent behavior.

Professional selection requires a system-level assessment of manufacture, properties, degradation, compatibility, installation, safety, regulation, maintenance and life-cycle effects. The most advanced material is not automatically the most appropriate; the best choice is the one that reliably satisfies the exposure, structural, functional and economic requirements of the project.

Key Terms

Polymer: A material consisting of very large molecules formed from repeating molecular units.

Monomer: A small molecule that can chemically join with other molecules to form a polymer.

Thermoplastic: A polymer that softens when heated and can generally be reshaped.

Thermoset: A polymer that forms a permanent cross-linked network during curing.

Elastomer: A polymer capable of large, substantially recoverable deformation.

Glass-transition temperature: The temperature region where an amorphous polymer changes between glassy and rubbery behavior.

Creep: Time-dependent deformation under sustained stress.

Stress relaxation: Reduction of stress with time under sustained deformation.

Bitumen: A viscous hydrocarbon-based binder used in paving and waterproofing.

Asphalt: Commonly, a mixture of mineral aggregate and bituminous binder.

Rutting: Permanent deformation forming longitudinal depressions in a pavement.

Stripping: Loss of adhesion between asphalt binder and aggregate due to moisture or related effects.

Composite: A material made from two or more distinct constituents with engineered combined performance.

Matrix: The continuous constituent that surrounds and transfers load to reinforcement.

Fiber-reinforced polymer: A composite containing reinforcing fibers embedded in a polymer matrix.

Anisotropy: Direction-dependent material behavior.

Pultrusion: Continuous manufacture of constant-section composite profiles by pulling fibers through resin and a forming die.

Delamination: Separation between layers or constituents of a laminated composite.

Compatibility: The ability of materials in contact to function together without unacceptable damage.

Life-cycle assessment: Evaluation of environmental impacts across defined stages of a product or system’s life.

Review Questions

Short Answer Questions

1. What molecular feature distinguishes a thermoset from a thermoplastic?
2. State two construction applications of elastomers.
3. Why is asphalt described as temperature-sensitive?
4. What are the principal functions of the matrix in an FRP?
5. Define material compatibility in construction.

Long Answer Questions

1. Compare thermoplastics, thermosets and elastomers in terms of structure, manufacture, properties, degradation and construction use.
2. Explain the manufacture and principal distress mechanisms of asphalt pavement.
3. Discuss how ultraviolet radiation, moisture, chemicals and temperature affect polymer products.
4. Explain why fiber orientation and substrate preparation are important in FRP strengthening.
5. Develop a material-selection procedure for a waterproofing system exposed to movement, sunlight and chemical contamination.

Analytical / Application Questions

1. A project requires a lightweight, corrosion-resistant handrail system near the sea. Compare painted steel, aluminum and pultruded glass-FRP, considering strength, durability, fire, maintenance and life-cycle issues. Recommend a solution with reasons.
2. A compacted asphalt mixture has Gₘᵦ = 2.36 and Gₘₘ = 2.48. Calculate the air-void content using the equation in this chapter and interpret one possible implication for pavement durability.
3. A concrete beam has sound concrete only in part of the proposed bonding area for a carbon-FRP strip. Explain why installation should not proceed immediately and identify the investigation, repair and quality-control steps required.

Multiple Choice Questions with Answers

Question 1

Which polymer class can generally be reheated and reshaped without first undergoing an irreversible curing reaction?

A. Thermoplastic

B. Thermoset

C. Elastomeric sealant after cross-linking

D. Cured epoxy

Correct Answer: A. Thermoplastic

Question 2

Which property is most directly associated with creep?

A. Time-dependent deformation under sustained stress

B. Instantaneous color change under ultraviolet light

C. Loss of aggregate grading during mixing

D. Increase in density caused by compaction

Correct Answer: A. Time-dependent deformation under sustained stress

Question 3

In asphalt pavement, rutting is primarily associated with

A. Permanent deformation under traffic loading

B. Only low-temperature thermal contraction

C. Complete elimination of air voids

D. Fiber misalignment in an FRP laminate

Correct Answer: A. Permanent deformation under traffic loading

Question 4

What is the principal structural role of fibers in a fiber-reinforced polymer?

A. To carry much of the tensile load in their effective direction

B. To dissolve the polymer matrix during curing

C. To prevent all fire-related deterioration

D. To make the composite isotropic in every direction

Correct Answer: A. To carry much of the tensile load in their effective direction

Question 5

Which condition is essential for successful externally bonded FRP strengthening?

A. A sound, adequately prepared substrate

B. Maximum possible surface moisture

C. Uncontrolled resin proportions

D. Removal of all matrix material from the fibers

Correct Answer: A. A sound, adequately prepared substrate

Question 6

Using Vₐ = 100(1 − Gₘᵦ/Gₘₘ), what is the air-void content when Gₘᵦ = 2.36 and Gₘₘ = 2.48?

A. 2.4%

B. 4.8%

C. 5.1%

D. 11.2%

Correct Answer: B. 4.8%

Question 7

For a unidirectional composite under ideal longitudinal loading, the simplified rule of mixtures uses

A. Eₗ = V_fE_f + V_mE_m

B. Eₗ = E_f + E_m regardless of volume

C. Eₗ = V_f/E_f + V_m/E_m

D. Eₗ = E_f − E_m

Correct Answer: A. Eₗ = V_fE_f + V_mE_m

Question 8

Which degradation mechanism involves radiation-induced chemical damage at the exposed surface of a polymer?

A. Ultraviolet degradation

B. Aggregate stripping

C. Hydraulic cement hydration

D. Pultrusion

Correct Answer: A. Ultraviolet degradation

Question 9

Why are thermoset composites difficult to recycle by ordinary melting?

A. Their cured cross-linked networks do not remelt into a processable liquid

B. They contain no polymer matrix

C. They are always soluble in water

D. Their fibers prevent any chemical bonding

Correct Answer: A. Their cured cross-linked networks do not remelt into a processable liquid

Question 10

Which statement best describes compatibility between construction materials?

A. They can function together without unacceptable chemical, mechanical, thermal or moisture-related damage

B. They have identical color and surface texture

C. They must always have identical strength

D. They must be manufactured by the same company

Correct Answer: A. They can function together without unacceptable chemical, mechanical, thermal or moisture-related damage