Ferrocement Photo Gallery

Ferrocement Photos


Ted Baumgart's Curved & Cantilevered Stairway


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29 files, last one added on Feb 01, 2005
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Random files - Ted's Gallery
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Photo 291587 viewsThe goal was to create a simple, modern, and clean looking stairway. Curved and cantilevered, floating effortlessly, goal achieved.
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Photo 15977 viewsAfter completing this I went back and rewelded each connection nice and tight. That took me a day. Why so much rod? This assembly will serve immediately as a functional temporary stair using the same mockup plywood now wired on top as treads. This gives everybody a break. At the house there is an ongoing remodel with contactors, not to mention the family and pets who live there. In this in-between state of being the rod must not warp or move. Notice the little rod trusses under each step to give support out to the edges. Underneath that are long horizontal rods pegged out from the 1/2" plate brackets for attaching the wire mesh. Now we are ready for mesh. Walking on these at this point tested their sea-worthiness. To dampen all vibration I additionally welded one hidden, short piece of 1/2" cold roll steel rod to the back of each step, connecting it to the huge pipe directly below it. This amounted to 'tripoding' each tread to the pipe dampening vibration in two axis. Wondering what the smaller pipe is protruding left under the bottom step? It's a hefty steel pipe, 1" diameter/ 3/8" wall, acting as a torsion arm attachment for a hand railing. I used a stainless threaded schedule 40 1" pipe coupling at it's end that set flush with the final FC/ECC mortared tread surface.
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Photo 04994 viewsBecause of the sloping site and the ongoing house remodel at the time, much stair work was performed in the shop using a full sized mockup of wood. As a starting point I measured and transferred the slope and proposed footings at the site to a plywood 'floor' and 'wall' in the shop, accurate to within 1/16". The first fabrication job was having the 8" schedule 40 pipe bent at the roll formers following the plans. The curved pipe was not made as a compound curve to simplify bending. A longer curved stairway would have to have a compound curve spine. Using a simple curved pipe made the stair treads float at varying heights above the pipe yet rise was held at 7-1/2" consistently. With the pipe ready the wood mockup was begun and the pipe let in via forklift, with wood treads to follow. Many mockup components were handy as full size reference guides allowing me to easily figure these details of alignment and sizes before committing to metal and FC fabrication. A mockup was truly necessary to make this a one-shot installation with no screw-ups. Later the plywood shop tread templates served as handy on-site rod and mesh covers prior to mudding allowing the client, pets, friends, and contractors to use the stairs unfinished.
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Photo 231326 viewsHere's the nitty gritty. This was the biggest bear to fight, getting the mudinto the mesh without voids. On a hunch I stopped by the local OSH hardwarestore and purchased toilet plungers to force the ECC mud. ...Any trick inthe book and then some. While holding four of them in my arms in theshopping isle, the guy next to me commented on the plumbing problem I musthave. He was a concrete engineer and we talked for an hour. He approved ofmy 'manual hydraulic mortar emplacement tool'. I'll explain how one must'roll' the mud into place to avoid voids. I learned it decades ago in dentallab on the plaster bench. Like a slow motion tsunami wave you push orvibrate the wet material outward directionally, never gulping air, neverencapsulating air or creating bubbles. You watch the leading edge of your'wave' as it consumes everything in it's path in slow-mo. Doing this with atoilet plunger was a new wrinkle. The 3 sizes of trowels were helpful butcouldn't generate the pressure needed to get the mud thoroughly through thewire mesh and protruding out below, like a meat grinder making hamburger. Weare talking about very physical work here. Given the time constraints ofinitial set, we really put our weight into the job. When satisfied withpenetration we then plopped on a mound of mud and spread it out on top,level with the aluminum angle forms. Last I floated a smooth finish andcrawled under the step to begin smoothing out the bottom. We are talking areal hump job here, given the time constraints of the setting ECC mortar. Ithelps that we had three of us, one continually mixing small batches, and twoothers schmushing and finishing. Also the days were cool, slowing the set.
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Photo 05971 viewsI this view of the mockup you can see the base plate at the bottom of the pipe that I eventually sunk into concrete with a lot of steel rod and angle chunks welded to it for mechanical adhesion. I don't know who's drink that was or what it was. The step treads are adjusted with 7-1/2" risers and a gentle slope to shed water. The top step will be exactly 7-1/2" below the finished landing-to-be at the site.
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Photo 011192 viewsThis particular little stair design is about a marriage of 1/2" steel plate and 8" diameter pipe to ferro cement treads in a live loading situation. There are easier choices in materials and methods for this situation but I wanted to test this combination out of curiosity regarding future projects. As people walk on these stairs the loading of the cantilevers asks the materials including the mechanical joint between steel plate and ferro cement to perform reliably in tension, compression, and for extra fun, torque. I didn't create molds for this job because this is a 'one off' project and each stair step is shaped differently. Using molds in a slightly different application would have been the better way to go for efficiency, labor savings, structural quality, and surface treatment. In the past I've cast metal structural frames into molds in a variety of venues from partial acrylic/ dentures and crowns/bridges in dental lab prosthesis to hidden epoxy 'belly boards' for 'flying' Superman patrons (hydraulically) at Universal Studios. These are similarly continuous live loaded appliances using metal frames molded into a plastic medium. This particular ferro cement stairway project proved to be intense in labor, but 5 molds would have been another major fabrication step for a stairway made exclusively for one site. I will reserve molding FC onto metal for similar but far larger projects. Anyway, I wanted to re-experience the pain and agony of wiring mesh, pushing mud into it, this time with PVA fibers in the mix.
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Photo 13921 viewsTo begin rod work, I took the full sized plywood step treads from the shop mockup and cut and welded my 3/16" cold roll steel rod on each plywood step. I compensated for the thickness of the future mesh and mortar by bringing in the rod work about 1/2" all around. I kept handy my little garden spray bottle filled with H2O to put out the wood fires as I welded the rod laying directly on the plywood. After welding in triangulation rods to stiffen the work, I took the new 5 metal steps-to-be to the site, ready to weld onto the armature, just as you see in the lower illustration. The widest step is about 8'/4" long.
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Photo 091127 viewsI liked the frame with the rust on it before sandblasting. Next step is powder coating. The client wanted it a gray cement color. This is a project about projecting modern clean lines, restraint, and simplicity through illusion, smoke, and mirrors. We are making magic.

Last additions - Ted's Gallery
ted29.jpg
Photo 291587 viewsThe goal was to create a simple, modern, and clean looking stairway. Curved and cantilevered, floating effortlessly, goal achieved.Feb 01, 2005
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Photo 281561 viewsThe stairway is complete but it's good to keep a perspective. It's just another day in the life with Willie, and Willie knows what's important.Feb 01, 2005
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Photo 261352 viewsDoes this look like bliss or purgatory? I was singing and soaring withnature's forces.Feb 01, 2005
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Photo 271676 viewsBelow is the mix low down, and above is another view of work in progress. After completion I wet cured the steps for a full 30 days before use. A temporary ramp with barriers protected the steps from all use. The steps were covered with plastic sheet and plywood mockup cutouts. The work was also tented tightly in 6 mil plastic sheet with 2 large shallow water filled plastic cement mixing tubs placed inside to keep the air humidity high for 30 days. The weather was Southern California December, 52-60 degrees F shaded from sunlight by the house eves and surrounding trees for great slow sets and a long, strong cure.ECC MIX MATERIALS:
1) Graded feldspar silica blasting sand, bagged and dry mixed in nearly equal portions by weight: #16, # 20, #30, #60, #90, #120 grit
2) Portland cement, low alkali, type II/V
3) 100% Acryl 60 (no water)
4) PVA (Poly Vinyl Alcohol) REC15 fibers 1/4" grid woven wire steel mesh (M/Steel, 4 X 4, 1.190 wire, roll 36"W x 111'L)MIX RATIOS BY WEIGHT:
The first batch was weighed with a scale in ounces, each separate ingredient placed on the scale in plastic Straus brand yogurt containers: 317 oz sand (combined weights), 60 oz cement, 4 to 7 oz PVA fibers (under 2% by weight), 19 oz Acryl 60 or more but kept to the bare minimum possible except in the batches being pushed into the interior of the space frames.
MIX RATIOS BY VOLUME: The weights chosen closely resemble the volume ratio of 1:3 cement/sand.MIX TOOLS:
A) Milwaukee heavy duty 1/2" angle drive drill, 4.5 amps, 0-500 rpm
B) Onebone style mixer, homemade, metal blades on all-thread
C) 5 gallon plastic buckets, half filledMIX METHOD:
The dry mix was given a short stir with the Onebone mixer, the liquid was immediately added, and all mixed for 30 to 60 seconds at 150 to 300 RPM.SET CONTROL:
Cool days and the Acyrl 60 gave us an hour to apply each batch of mix as long as it was spread out and not massed in any container where chemical reaction heat could accelerate the set. (Each stair step took 4 to 6 buckets half filled.)BUBBLES: Slow rising air bubbles were a problem if the surface was float-troweled too long. The Acryl 60 did not let bubbles rise and dissipate easily. Various vibration techniques were briefly tried but not liked. Short slow power mixing, the no-air-encapsulation mud application technique previously mentioned, and a quick and efficient trowel finish on the top were the answers to bubble potential. "Johnny, don't play with your potatoes!"
Feb 01, 2005
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Photo 241267 viewsLook for the pasty yellow looking thing under the step, that's my armworking from below. I spent more time below than above because there wasmore surface area to finish, and it wasn't flat work, but rather on-my-backconvex and curvilinear finished surfaces. Did I mention that each step tookhalf a day to mud, including cleanup? If this were sprayed into a mold itwould have been a half hour.Feb 01, 2005
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Photo 251158 viewsThe most spiritual part of the job was in smoothing out the convex cuppedlooking areas underneath each step, largely hidden from view. Because of thelittle rod trusses previously mentioned, each step had regularly spacedbumps under them to deal with. They created little convexities between them.I grabbed the smooth Mexican beach pebbles you see as shaping and smoothingtools. I quickly began hearing surf sounds in my head, while slurping andsliding, and gliding the smooth rock over wet mud. An occasional spritzingwith the water spray bottle lubed the process. I began connecting sculpturalshaping with nature's forces, feeling like a magnetism was pushing my hand.I also realized I had been under the steps too long and had a long way togo. Go with the flow I say. I began singing.Feb 01, 2005
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Photo 231326 viewsHere's the nitty gritty. This was the biggest bear to fight, getting the mudinto the mesh without voids. On a hunch I stopped by the local OSH hardwarestore and purchased toilet plungers to force the ECC mud. ...Any trick inthe book and then some. While holding four of them in my arms in theshopping isle, the guy next to me commented on the plumbing problem I musthave. He was a concrete engineer and we talked for an hour. He approved ofmy 'manual hydraulic mortar emplacement tool'. I'll explain how one must'roll' the mud into place to avoid voids. I learned it decades ago in dentallab on the plaster bench. Like a slow motion tsunami wave you push orvibrate the wet material outward directionally, never gulping air, neverencapsulating air or creating bubbles. You watch the leading edge of your'wave' as it consumes everything in it's path in slow-mo. Doing this with atoilet plunger was a new wrinkle. The 3 sizes of trowels were helpful butcouldn't generate the pressure needed to get the mud thoroughly through thewire mesh and protruding out below, like a meat grinder making hamburger. Weare talking about very physical work here. Given the time constraints ofinitial set, we really put our weight into the job. When satisfied withpenetration we then plopped on a mound of mud and spread it out on top,level with the aluminum angle forms. Last I floated a smooth finish andcrawled under the step to begin smoothing out the bottom. We are talking areal hump job here, given the time constraints of the setting ECC mortar. Ithelps that we had three of us, one continually mixing small batches, and twoothers schmushing and finishing. Also the days were cool, slowing the set.Feb 01, 2005
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Photo 221269 viewsTalk about getting 'at one' with the work, I'm 'into it'. Notice thealuminum angle as edge forms for crisp corners. You can get away with lessprecision if you somehow strike clean edge lines on your work. The angle iswaxed and then tie-wired in place to the mesh, to be removed after ECCplacement and cure. Notice how they hang loose until packed with ECC. That'sto give the precise space for the ECC to cover the mesh. You can see plasticsheeting under the plywood, it's covering the exposed mesh to slow therusting in the rains we had been having. I used that plastic later to coverour newly troweled ECC steps too. I didn't want plywood to sit on the curingECC sucking moisture. The pipe plug is protecting the threaded stainlesscoupling inside the ECC. That coupling is the means of attachment for ahandrail should one be desired. The clamps are holding more aluminum angleserving as crisp forms where mud will meet the steel plate brackets.Feb 01, 2005