Pre-defense communication check

Editor's Notes

• #2: FRC or BFRC
• #3: The backgroound for the development of this project is based on 3 fundamental issues: Issue # 1, economic – affordable constituents, basic, will expand the applicability of this strengthening systems Issue # 2 sustainability – for the development of the composite industry, environmentally benign materials need to be developed, in order to keep competitive, safe for users / workers and compatible with the environment Issue # 3 technological – the generation of toxic fumes, and fire protection, the possibility of reversibility, expanding the use of this systems to historic structure. Here we can refer to the recent Earthquake in l’Aquila.
• #4: The structure and overview of the project followed a top down approach to select on the one hand structural fiber material made from both glass and basalt in different fiber architecture (namely a grid type and a sheet type) to be implemented with inorganic matrices (cement based). For this part of the system, the criteria for the selection of the grouts consisted in reach an adequate degree of "wettability", thus requiring relatively fine based grouts provide sufficient bond strength: though confinement is a contact-critical application, the need to bond with the concrete substrate is necessary to transfer load to the fibers, ensuring that good contact is maintained while the grout cures with the reinforcing fibers; allow adequate curing time to ensure workability when preparing the samples ensure dimensional stability (shirk stability) Two roots where followed: 1) Hydraulic cement-based matrix with high water retention, extreme fine aggregate and paste rich, yielding a cohesive grout. and an acrylic based matrix. 2) A Two part acrylic-modified Portland cement based matrix, which creates a flexible breathable matrix. A third was also investigated –Single component magnesium-phosphate-based matrix, with a 15-minute setting time and good bonding capability without an added bonding agent. This last one did not have the appropriate properties due to its limited workability. Following the feasibility study form last year, a Low density sheet type fiber material and Hydraulic based matrix where selected to be most adequate.
• #5: Based on those discoveries, Charecterisation of materials through direct tensile testing as per ASTM D3039and ACI 440 Different number of plies and double coupon to test for overlaps are being tested.
• #6: Furthermore, a Qualitative and Quantitative Environmental Impact Analysis of a FRC system was carried out to understand and evaluate the benefits of implementing BFRC vs a typical GFRP strengthening system contributi9ng towards environmentally benign alternatives, Its important to acknowledge that the NSF is also pushing toward this type of studies with the SMM program: Structural Materials and Mechanics program : Mechanics of alternative structural components in the built environment Structural components consisting of natural and synthetic materials Impact on life-cycle performance and sustainable development of the civil infrastructure This type of study in composites is not usual in the industry, but clients are demanding more understanding of the long term impact of this material systems to help them in their selection decision. 3 parts where analyzed: VOC emissions: Determined using and environmental chamber (ASTM D5116 and COST Project 613, Report No. 8) through photoionization detection (PID). Embodied energy: The criteria for selection used for strengthening systems was extracted from the ‘Inventory of Carbon & Energy (ICE)’ version 1.6a1. Life Cycle Assessment (LCA): ASTM E 1991 and ISO 14042 was used as reference, to determine which strengthening system, per unit kilogram, had the least effect on human health and the environment, as per the carbon produced in the application of the system. Results though some what predictable, where staggering in the difference in magnitude…
• #7: Firstly the VOC emissions, this has particularly significance when strengthening existing habited buildings VOCs greatly after the indoor air quality of an internal room, and this in turn the health, performance and safety of both workers applying the systems as well as future occupants: relating to the ‘sick building syndrome’ A stagering 130% less particles per million of VOCs where emitted by a cement based matrix. This is a significant amount to improve the flexibility of a strenghting material, so occupants can retun to the building as fast as possible with minimal disturbance, both physical and health wise.
• #8: Secondly the embodied energy, this is important to use the resources we have more efficiently, exploiting those readily available material (reducing in extraction and manufacturing/process energy) Recyclable materials here play an important role, as their energy can be reused. Disposal is even more important as in some cases disposal of FRP based materials are treated as hazardous waste, introducing costly unfamiliar and burocratic process in construction industry. Once again, results show that a BFRC based system needed 87% less energy in Mega joules per kg (Joule is the energy exerted by a force of one Newton acting to move an object through a distance of one metre ) this is a significant result given that it is two iorders of magnitude in difference. Notice that most of this is based on the matrix, since the basalt and glass fibers have similar energy needs. Furthermore, notice the lack of primer needed to apply FRC based materials (further reducing costs of this systems) and energy needs. The criteria for selection use for strengthening systems was extracted from the ‘Inventory of Carbon & Energy (ICE)’ version 1.6a1. . G.P.Hammond and C.I.Jones (2008) Inventory of Carbon & Energy (ICE) Dept. of Mechanical Engineering, University of Bath, UK. d
• #9: Thirdly the LCA based on the carbon released by the use of this materials, followed a similar tred to that of the energy, thought this time the matrix for the FRC based systems is slightly higher, none the less it is two orders of magniture less, 77% less carbon in kgCo2/kg emitted than traditional FRP based products. Note that This assessment did not include the disposal of the systems, as limmited information was available, but if this was accounted for the percentage in difference would have probably been higher.
• #10: Overall the BFRC system …… And BFRC can be implemented as a sustainable strengthening composite system, developing the implementation of green building construction rehabilitation systems . Most importantly this study opens a window and posses a question of consideration for new development of this systems, specially by the tendency that the industry and leading clients within that industry are following: the LEED program
• #11: For this I would like to open a parenthesis. LEED…. The Leadership in Energy and Environmental Design (LEED) Green Building Rating System™ encourages and accelerates global adoption of sustainable “green” building and development practices through the creation and implementation tools and performance criteria. As a LEED Accredited professional, I have come to acknowledge that Sustainable construction requires a critical review of prevailing practices, economics, techniques, materials and their sources: it’s a holistic approach. Adoption of this environmental strengthening systems would certainly be welcome as it relates to current criteria of LEED for existing buildings. It is an important movement to bear in mind, with this I would like to close parenthesis
• #12: I would like to acknowledge the help of Dr. Jacqueline James as she has been a key person in the development of the environmental analysis. as well as Dr. Matta and Dr. Nanni for their guidance and support.
• #13: This spin of project is based on developing a new test methodology to achieve more realistic charaterisation values of materials that are being applied in cylindrical geometries Such as FRP jackets on circular columns.
• #14: As you might be aware, characterization of materials in cylindrical fashion are tested in direct tension, based on a cut of a free body diagram, the confining pressure fl exerts an effective stress ffe in the jacket which ultimately creates the triaxial state of stress, this stress comes from a tensile force which is a tangent to the circular geometry. Nonetheless, literature has shown that the values achieved in jackets significantly different to those achieved in direct tension. Furthermore ACI establishes a reduction factor in material properties, whenever this strengthening geometry is used. This is because the direct tensile characterization procedure yield an upper bond level of material characterization. The development of a true hoop approach would yield a lower bound and thus safer approach and better understanding on the influences of geometry and state of stress.
• #15: Previous methods took two approaches: 1) Mechanical – by developing machines that mechanically applied and internal force to a circular geometry, like ASTM D 2290 which uses the split disk method. This test has numerous limitations and is not used. 2) Hydraulic – Applying internal pressure though fluids to this type of samples. Nonetheless the high cost of the testing machinery and the high pressures needed to reach to reach failure of the samples made this methods highly unsafe and costly, as well as un practical due to the nature of this dirty method, you can imagine that after failure the fluid would be everywhere. With this approach we are using the natural expansion of water when freezing – ICE to load the materials by creating that internal pressure. On this note, it is important to acknowledge that ice is a complex material…. ASTM 2290 - Standard test method for apparent hoop tensile strength of plastic or reinforced plastic pipe by split disk method
• #16: An important item for the development of this test ICE methodology is the need to create this internal hydristatic (uniform) pressure. Two methods to follow are The Chemical root, modifying the material (water in this case) to enhance homogeneous formation of ice crystals, potentially this could be done by mixing a colloid to water (such a milk) Mechanical root, apply vibrations to the water while freezing, stering the water while freezing, ensuring that any air bubbles rise to the surface. Both paths are being explored….
• #17: The experimental test setup aimed at developing a practical simple and clean test method, practical which can be repeatable, cost effective and in a circular manner to have a true material characterization. As you can see we developed a traditional type of pressure vessel, using thick constraining end plates and bars ot join them. Metal cans where selected as initial samples, as a source of consistent and known material to develop the method with the intention to later transfer this method to composite based materials. Internal temperature, strain where recorded. Data comparison with direct tensile tests for validation is also part of the experimental campaign.
• #18: As a preliminary feasibility study, we looked at the strain distribution, as expected the highest strain was experienced at the centre and was very similar at the ends as seen formthe diagram. Black line represent the dummy to account for temperature differences.
• #19: Also the failure of the cans and the deformation they undertook can guide us to the development of this test methodology. By taking basic 1D assumptions such as a fixed end beam and its deflection under a uniform distributed weight it can help us visualize and obtain a feel for the possibilities of development of this methodology. Further use of the theory of shells for a thin circular shell structure under internal hydrostatic pressure with fix end conditions will help in understanding and developing the test method.
• #20: As part of the results of the feasibility of ice expansion as a load to determiner circumferential we can see the strain at the centre of a steel can, undergoing an in the first stage a negative strain (this is the contraction of the metal at cold temperatures) and then after nearly 1hr and 45min the start of a stain being experienced increasing will a first peak or about 5750 micro strain (0.575%) Notice on the pictures the yield lines and failure of the can. Overall the potential to develop a ‘clean’ practical cost effective, test method without the need of expensive or sophisticated loading machinery, essentially using nature’s force to characterize materials is novel. Furthermore the ability to have a better understanding of the material characterization under this geometry could guide us to safer designs and more realistic reduction factors, if needed in any case.