Bai ging vt liu FRP references (1)

An Introduction to FRP Composites for Construction Nguyen Huy Cuong Source Composites FRP For Construction Module Objectives To provide students with a general awareness of the application of FRPs for concrete structures To facilitate the use of innovative and sustainable materials in the construction industry To provide guidance for students understanding principles of strengthening reinforced concrete structures with FRP materials Composites FRP For Construction Handling and Application of FRPs for Strengthening Handling and Application of FRP Reinforcement Outline Introduction and Background FRPs in Construction Composites FRP Section: For Construction SECTION 1: Introduction and Background Composites FRP For Construction Introduction and Overview Section: • Humankind has used many building materials throughout history: • • • • Stone Timber Steel Concrete Used for Millennia Past two-hundred years • Modern urban landscape is now defined largely by steel and concrete • Roads, sewers, highways, buildings, bridges • Complex infrastructure systems enabling health and prosperity Composites FRP For Construction Introduction and Overview Section: • Our infrastructure systems are deficient • Neglect, deterioration, overuse, upgrade Global Infrastructure Crisis  How can we prevent deterioration of infrastructure?  How can we prolong the lives of existing structures? Composites FRP For Construction Introduction and Overview Section: • A primary factor leading to extensive degradation… Corrosion Concrete Reinforcing Steel Moisture, oxygen and chlorides penetrate Through concrete Through cracks Corrosion products form Volume expansion occurs More cracking Corrosion propagation End result Composites FRP For Construction Introduction and Overview Section: • Why build and repair with the same materials? • Why repeat the cycle? Lightweight High Strength Easy to handle 5x steel FRP Materials Corrosion resistant Durable structures Highly versatile Suit any project Composites FRP For Construction Fibre Reinforced Polymers Section: General • FRPs are composite materials: • materials created by the combination of two or more materials, on a macroscopic scale, to form a new and useful material with enhanced properties that are superior to those of the individual constituents alone • More familiar composite materials • • • • Concrete → stone, sand, and cement paste Reinforced concrete → concrete and steel Wood → cellulose and lignin Bone → collagen and apatite Composites FRP For Construction Introduction & Background Section: • What is FRP?  FRP is a composite: Composite = combination of two or more materials to form a new and useful material with enhanced properties in comparison to the individual constituents (concrete, wood, etc.) High-strength fibres  FRPs consist of: Fibres Matrix Polymer matrix Composites FRP External Reinforcement: Installation Section: For Construction  Curing conditions: Installation • FRP systems must be cured for an adequate period of time under acceptable temperature and humidity  Temperature: 4~10ºC < T < 35~55ºC  Relative humidity: RH < 85% • Common epoxy resins reach their full design strength in about days Composites External Reinforcement: Installation FRP For Construction Section: Installation • Alternative techniques  Various additional techniques are available: • Near surface mounted (NSM) systems • Filament winding techniques • UV curing resins Filament-wound FRP wraps Composites FRP For Construction QC & QA • Quality control (QC) and quality assurance (QA)  The performance of FRP strengthening systems largely depends on the quality of the materials and the care taken by the applicators ISIS EC Module Section: Composites FRP For Construction QC & QA Basic Checklist: Quality Control & Quality Assurance   FRP systems & materials qualified by the Engineer All staff educated & certified in the use of FRP systems Inspections conducted regularly by trained personnel Pre-installation: -Concrete / FRP -Concrete substrates & surface preparation inspected  During Installation: -quantities of materials used / rates of application -environmental conditions -fibre alignment / witness panels Post-installation: -voids & delaminations -cured FRP thickness -bond testing / load testing Section: Composites FRP For Construction QC & QA Section: QC / QA • Contractor/applicator qualifications:  Only certificated personnel should install FRP systems  Installation specialists who have been trained in the application and handling of the specific FRP systems should be used  Training is typically the responsibility of the FRP suppliers Composites FRP For Construction QC & QA Section: QC / QA • Inspection and field quality control:  Inspections should be carried out before, during, and after application of the FRP materials  Inspections should be conducted by a trained and certified site engineer  Items of interest • Concrete substrates and surface preparation • The presence and extent of delaminations • The adequacy of resin cure, adhesion, FRP thickness, bond properties etc Composites FRP For Construction QC & QA Inspection and field quality control (cont)… Section: QC / QA  Pre-installation: • The concrete substrate and the FRPs should be inspected prior to application  Concrete  FRP • Concrete strength (pull tests) • Surface roughness, holes, cracks, protrusions • Sharp corners, other imperfections • Mechanical properties (strength/modulus) • Physical properties (thickness etc.) Composites FRP For Construction QC & QA Inspection and field quality control (cont)…  During installation: • Mixing and installation times, temperatures, and relative humidity should be monitored and recorded • A trained field supervisor should be present at all times • Fibre directions and alignments should be verified during the installation process Section: QC / QA Composites FRP For Construction QC & QA Inspection and field quality control (cont)… • Typical selected inspection items (ACI 2002, CHBDC 2006):  Surface preparation methods/surface roughness (ICRI, 1997)  Widths of existing cracks not repaired by epoxy  Details of the specific FRP batch numbers  As-installed fibre orientations and material properties  Results of delamination surveys/pull-out tests  The cure of the installed system  General progress of the work Section: QC / QA Composites QC & QA FRP For Construction Inspection and field quality control (cont)…  Post-installation: • Various tests are performed after installation of FRP strengthening systems to provide assurances of the system Inspection for voids and delaminations Void and delamination repair Cured FRP thickness Bond testing Load testing Section: QC / QA Composites FRP For Construction QC & QA Inspection and field quality control (cont)… • Inspection for voids and delaminations Visual and acoustic tap test inspection: • Debonded areas • Air pockets • Voids beneath the FRP Section: QC / QA Composites FRP For Construction QC & QA Inspection and field quality control (cont)… Section: QC / QA • Void and delamination repair: Delamination areas < 1300 mm2 No repair required if area of the delamination is < 5% of total bonded area if not more than 10 delaminations/m2 Delamination areas > 16000 mm2 Repaired by cutting away affected area of FRP sheet, reapplying primer and leveling putty, and applying an overlapping patch of FRP sheet Delamination areas 1300 mm2 to 16000 mm2 Repaired either by low-pressure injection of resin saturant into the void beneath the delamination, or using patching Composites FRP For Construction QC & QA Section: QC / QA Inspection and field quality control (cont)… • Cured FRP thickness: Small FRP cores may be taken from non-critical areas • Load testing: To verify the in-service performance of the FRP system • Bond testing: Direct tension bond testing on the installed FRP system Desired failure mode is cohesive failure occurring in the concrete Tensile strength >1.4 MPa Pull-out test Composites FRP For Construction QC & QA • Common safety precautions:  Avoid contact with skin and eyes (Safety glasses, impermeable gloves, and disposable suits)  Epoxies should only be handled in well-ventilated areas  Heavy-duty gloves should be worn at all times when handling fibre fabrics and FRP sheets Section: Composites FRP External Reinforcement: Maintenance Section: For Construction • Maintenance and repair of FRP systems  Long-term inspections and assessment include general visual inspections (appearance, debonding, cracking, blistering, etc.)  Pull-off test or structural load tests may be performed  If damaged, a specialist engineer should determine the causes and remedies for the observed damage ... All -FRP structures • FRP hybrid structures Section: Composites FRP For Construction Examples of FRPs Section: FRP Materials Unidirectional glass FRP bar Carbon FRP prestressing tendon Glass FRP. .. structures with FRP materials Composites FRP For Construction Handling and Application of FRPs for Strengthening Handling and Application of FRP Reinforcement Outline Introduction and Background FRPs in... pulled through Composites FRP For Construction Pultrusion Manufacturing FRP Materials Section: Composites FRP For Construction FRP Rebar Section: Manufacturing • To enhance an FRP bar’s mechanical