Pinkerton, chief technology officer of Helix Steel. My ... · PDF fileIRC. Micro-Rebar. Presenter ... the behavior of anything you mix with concrete is \൦undamentally governed by
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Chuck Wilson Helix Steel – Tech Support/Distribution Manager – North America 425-239-8760 Micro-Rebar Technology Superior Concrete
Presenter 2015-02-10 18:09:47 -------------------------------------------- (Luke standing next to the presentation) I’m Luke Pinkerton, chief technology officer of Helix Steel. My background is in structural engineering, and I've been involved in the concrete industry and Helix for 18 years.
Micro-Rebar
Helix is Only Steel Fiber Approved as Primary Steel in Structural Concrete
ISO/IEC Guide 65 Evaluation Report –UER279 Issued and in use.
• Assurance of Structural Capacity• Assurance of Fire Resistance• Public Reviewed Design Method• ISO/IEC 17025 (IAS) Laboratory• Recognized in 99 countries
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Presenter 2015-02-10 18:09:47 -------------------------------------------- (Luke only) With a design model complete, the next question is, if Helix is not mentioned by name in my design code, how can I use it? Is it approved? The simple answer is yes. All codes hat we are aware of have performance based alternative design allowances. In an effort to not stifle innovation, even the most prescriptive codes have a statement that says you can use alternative methods and materials if you can show that the it performs at least as well as the design prescribed in the code. The American Concrete Institute recently clarified that Helix may be used in any application provided it meets this requirement. (same slide full screen) To make the process easier for you, we worked with Uniform ES, an ISO Certified Product Reviewer, to review the entire design approach and all the data and compile it into a short design manual. The manual, referred to as an Evaluation Service Report or ESR, provides everything required by building codes in over 90 countries to allow the approval of Helix. To use Helix, it simply needs to be added to the drawings as an alternative design completed in accordance with the ESR to the drawings. Uniform ES provides the assurance to the building official with final approval authority that Helix meets the performance criteria in the code.
Helix Developed for the Militaryfor Blast Resistant Concrete
1990’ies
Rebar Only With Helix & 50% Less Rebar Only Helix Can do This!
30 Lbs of C4 Explosive
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Presenter 2015-02-10 18:09:48 -------------------------------------------- (this slide full screen with Luke’s voice in the background) The images shown here are the results of 10lbs, or 5 kgs, of C4. As we know, concrete is brittle. Even two layers of rebar spaced at 4 inch (100 mm) could not prevent the concrete from shattering under the blast. When Helix is added and the rebar used is half the rebar-only design, the spauling is virtually eliminated. Fundamentally, Helix works like a composite material. In this case it allows the concrete to flex under the load, forming many smaller cracks. (Cut to Luke only) Simply put it makes the concrete more ductile without adding cost.
12 Years and 30 Countries: Slabs – Walls – Footings - Complex
Structures
audi logo
Micro-Rebar
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Presenter 2015-02-10 18:09:48 -------------------------------------------- (Luke’s voice in the background with scrolling/flashing pictures shown full screen – please take creative editing liberty to best display this information) The applications for Helix are widespread. There is really no application where Helix has not been used. Applications ranging from simple slab on grade and slab on metal deck to complex structures like multi story cast-in-place buildings and foundations.
• Length: 1.0 inch (25 mm),• Equivalent diameter: 0.020 inch (0.5 mm)• Rectangular Cross Sectional Shape• Each Helix Micro-Rebar has a minimum of one
360-degree twist.• 11,000 parts per pound
Micro-Rebar
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Presenter 2015-02-10 18:09:48 -------------------------------------------- Bury us with testing?
Approval PedigreeANSI ISO/IEC 65
• IAPMO's Uniform Evaluation Service (UES) Evaluation Report ER-279 on Helix 5-25 Micro-Rebar.
• This report accredits Helix Micro-Rebar 5-25 and its design method under ISO Guide 65 for use as an alternative to conventional rebar and wire mesh in concrete.
• Helix Micro-Rebar 5-25 is the only discontinuous concrete reinforcement product in the world that now has a ISO certified design manual that can be followed to design vertical applications (such as walls) with Helix as the primary concrete reinforcement.
Assessed Properties
• Helix 5-25 Micro-Rebar functions as tensile reinforcement for concrete.
• Helix Micro-Rebar may be used to reduce shrinkage and temperature cracking of concrete.
• Helix Micro-Rebar may be used as tension and shear reinforcement in other structural concrete as detailed in this report which satisfies the requirements of ACI 318 Section 1.4 and Section 104.11 of the IBC and IRC.
Micro-Rebar
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Presenter 2015-02-10 18:09:48 -------------------------------------------- Bury us with testing?
Micro-Rebar
Helix Design Classes and Selection
Class Assumptions Applications
A Micro-Cracking 1FS 3.7
Strain Limit 110 με
Shrinkage and TemperatureSoil Supported Structures
Suspended Cast in Place Concrete, Other Structures, Limitation Apply
Helix Design Classes Class B Example – Wall
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(this slide full screen with Luke’s voice in the background) Class B is for structural concrete but it is limited to soil supported structures, arch structures or walls with lateral supports at less than 24 times their thickness. These are the same application requirements that the American Concrete Institute imposes on plain concrete structures. Designs in this class are not allowed to exceed the tensile strain limits for the “Proactive” phase. The objective is to keep the strains low to minimize the formation of visible cracks. Class B has an average factor of safety of 5.
Helix Reinforces ConcreteBefore the First Crack
First Crack Point with
Helix Concrete
Helix Reinforces Concrete Before it
Cracks.
First Crack inConcrete withRebar, Plasticor Metal Fibers
Plastic Fibers Do Nothing
Micro-Rebar
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Presenter 2015-02-10 18:09:49 -------------------------------------------- (show Luke next to presentation, Luke will point at the chart) Let's take a little closer look at the first part of the curve, which we call the proactive part of the curve. With Helix, we actually get a very interesting behavior that we are not aware is possible with any other type of reinforcement presently on the market. If you look at the two curves, the red curve is plain concrete and the black curve is reinforced concrete with 25 lb/yd (15 kg/m3) of Helix. What we see is a statistically significant reduction in the modules of elasticity and an increase in the strain capacity of the concrete. (same slide full screen) What this means is that the concrete is actually more flexible and can tolerate more tensile strain before a dominant crack forms. The slope of the red curve about equal to EC, but when you add Helix, it actually decreases the slope with a stable, perfectly plastic plateau. The amount of energy required to form the crack is more than twice that of plain concrete. Just a reminder, rebar is not active at all until the concrete cracks.
Helix Micro RebarProven to be Micro Rebar
Helix Performs identical to Rebar
Steel Fibers Fail at This Point
Plastic Fibers Do Nothing
1/4” (8 mm) Helix Micro Rebar
Untwisting Governs
Bond StrengthMicro-Rebar
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Presenter 2015-02-10 18:09:49 -------------------------------------------- (show this slide full screen with video playing next to graph while Luke talks about the lines on the graph – the video shows the Helix untwisting as it’s being pulled through concrete which is what he’s talking about. He will specifically reference the green and blue lines on this graph) What really makes Helix different is its characteristic twisted shape. Look at the green curve on this graph, this curve looks very similar to the red curve I showed on the previous graph. It's an elastic perfectly plastic type behavior. This occurs because Helix must untwist to come out of the concrete, the torsion from the untwisting process is the source the the constant resistance. People have been trying to do this with concrete for, centuries. The problem is, the behavior of anything you mix with concrete is fundamentally governed by friction. Friction is just a function of how much surface contact there is between the reinforcing element and the concrete. The blue curve shows the instability that occurs with frictional bonds, in this case a straight fiber, with increasing strain. (show Luke only) There are other products that have some deformations on them, but they're still ultimately governed by friction. Often you'll see long fibers that are really designed to maximize the amount of surface contact between the fiber and the concrete. The fundamental difference is that they generate a constantly decreasing amount of resistance as strain increases. You cannot design concrete with an unstable form of reinforcement. Helix changes everything because it’s the first discontinuous reinforcement that offers stable tensile behavior through its untwisting failure mechanism.
Synthetic Fibers Allow 3 mm WidthCracks
Plain Concrete is Stronger than Concrete with Plastic
Forta Fibers
Green - Max Crack Width Allowedby ACI 318 – 0.015 in or 0.40 mmBlack dash – visible crack size0.02 inch
Crack Facts
1. Helix begins to take tension load at 10 microns2. Helix has full UTS at 0.0002 inch3. Visible crack starts at 0.002 inch4. Water tight concrete can be achieved at 0.0079 inch5. Maximum ACI 318 crack width allowed is 0.0157 inch6. Rebar and Steel Fibers take tension load after 0.039 inch crack7. Plastic Fibers Stretch out to 0.118 inch (per direct tension testing)
Which Product do you think produces Superior Concrete?
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Presenter 2015-02-10 18:09:50 -------------------------------------------- (this slide full screen with Luke’s voice in the background) With that, I appreciate your time and attention. I look forward to working with you as you begin to work with Helix. Thank you.
• Helix concrete mix specification required• Shrinkage strain is included in strain
check calculation must use class C design if strain limits are exceeded.
• Some hairline cracks are expected• Special Detailing for Joint-less Slabs
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Bury us with testing?
Heavily Loaded SOG
• Project - A slab designed forheavy loading was specified at 16” thick and with #6 barspaced at 9” both top & bottomwith a 6-6-6-6 mesh.
• Helix Design - 50 lbs/yd of Helix replaced rebar andmesh, increasing the first crack resistance by 84% andresulting in a 42% cost savings.
Micro-Rebar
Refinery Piles
• Project – Refinery typical concrete pile – (12) # 8 vertical rebar with #4 horz on 12’ oc.
• Helix Design – 45 pounds/cyof Helix reduced the rebar to(4) #6 rebar – horiz steel, onlyneeded at anchor bolt area andfor ease of construction.
Micro-Rebar
Wind Farm Foundations
• Project – 53 Wind farm towersin Washington with large concrete and rebarfoundations.
• Helix Design – 45 pounds of Helix reduced the rebar use and would have saved thecontractor $880,000 in material costs over all towers IF, they had known about Helix……..
Micro-Rebar
Thin White Topping.
• Project – Commercialpavement rehab.
• Helix Design – 1.5 inch to1.75 inch parking lot with 20 pounds of helix and the tractor trailer and loaded van rolled over it.. .no cracks.
Micro-Rebar
Sidewalks
• Project: A large universitypours 8” thick sidewalks to allowheavy equipment to drive over the surface. Engineers werelooking for a way to decreasecosts without sacrificing strength or quality.
• Helix Design: Helix was added at a dosage of 20 lb/yd in a 6” thick slab. The result? Acost savings of 15% and greatly increased strength over the
Micro-Rebar plain 8” concrete.
• Project: 12” thick concrete was poured to allow heavy equipmentto drive over the surface. After three years, the road was in shambles.
• Helix Solution: Helix was addedat a dosage of 40 lb/yd but with only 6” of concrete. The result? After three years, the road doesn'thave a single visible crack and it was 20% less expensive to pour.
Case Study: Mining Road
Growing List of DOTs including:• Virginia• North Carolina• Texas• Michigan• Georgia• Oregon• Mexico
Interstate Highway
Interstate Highway
• Project: Oregon DOTtest pour at milepost 211, south of Corvallis.
• Helix Design: Dose at 37lb/cy to replace all rebar, but ODOT decided to include rebar and test for durability. Additionalpours are beingconsidered.
Tunnel LiningsHelix 8-50
• Deflection hardening at 36 kg• Requires 20%-40% lower
dosages than hook ended steel fibers
• Performs in high strength concrete
• Increased splitting tensile
Micro-Rebar
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Presenter 2015-02-10 18:09:57 -------------------------------------------- Bury us with testing?
Helix 5-25 Shotcrete
• Optimized for current Civil Tunnel Specifications• Provides Superior performance at low deflections in RDP and ASTM
C1609. Plastic fibers do not perform until deflections are high
Micro-Rebar
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Presenter 2015-02-10 18:09:57 -------------------------------------------- Bury us with testing?
ICF Construction Example
• Project: ICF Wall rebar bothhorizontal and vertical rebar.
• Helix Design: rebar bothhorizontal and vertical replacedby Helix. Lintel horizontal remains, and one vert on eachside of windows and doors. Dowel between cold joints.
Micro-Rebar
Twisted Micro-Rebar Technology Isthe Only Micro Rebar Approved as
Structural Reinforcement in Structural Concrete.
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Presenter 2015-02-10 18:09:57 -------------------------------------------- (this slide full screen with Luke’s voice in the background) With that, I appreciate your time and attention. I look forward to working with you as you begin to work with Helix. Thank you.
