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 231334 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 011198 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 06880 viewsNotice the torsion tube with it's mockup stair brackets in place. As a piece of sculpture I canted the brackets for sex appeal. They rise diagonally from the sloped pipe. The idea was when you step on a tread the bracket loading would send the forces in a prescribed direction. If these tall brackets were positioned truly vertical, the steps would be too squirrelly underfoot, maybe moving toward you and maybe away. Under these circumstances of use even 1/2" plate can move like jelly and sure footedness is a good trait on stairways. These were not to be curiosities that danced and mushed around underfoot. That would be for a different client. I'd do an extremely kinetic stair for my private amusement park, which is called home, but a grandma wouldn't get on it. I later tested the treads as I welded the rod at the house. They were squirrelly all right. What an interesting feeling stepping on stairs that moved around like air mattresses in the water. I laugh at the fun, but I'm glad they tightened up as I welded more rod in, and especially after the ECC mortar was in place and cured. I could have called them The Drunk Stairs otherwise.
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Photo 261354 viewsDoes this look like bliss or purgatory? I was singing and soaring withnature's forces.
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Photo 081004 viewsAfter lifting off the wooden mockup as a unit and putting it aside, we are now looking at the steel armature that appears more interesting than the final product might. This is like looking at a painting being made and noticing that the painter's pallet looks better. I could walk away now exclaiming "Eureka, this baby's done!", but it wouldn't function as a stairway. I saved the particle board templates created as guides used for plasma cutting the steel brackets to exacting dimensions. The squiggles on the top edges were designed to increase the mechanical interface between the steel plate and the FC treads yet to be built. I didn't want to create a straight parting line where forces might accumulate and form a crack. A good marriage has many ties. Posing oddly with sledge hammer and screw gun is one of the best structural welders I've met, Mario Perez. He took knowledge of metallurgy to the molecular level, careful not to weld completely around the pipe, and mainly on one side of each bracket. The mark of experienced structural welders is not how much weld metal they throw into the work, but how little, the weld being the weakest part. He didn't want to generate cracks, or warp things in the process. This is seen in the photo of the sandblasted frame. Notice that the brackets encircle the pipe to physically grab the entire circumference like a strap, transferring the loading all around the pipe. The brackets will work as true torsion arms when you step on the stair treads cantilevered off of the pipe's side. But why is Mario holding a sledge and screw gun? "If it doesn't go in one way, it's going in another. You try screwing into 1/2" plate." We joke.
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Photo 191040 viewsThe rod was there longer than the mesh as this closer view reveals rust on the rod but not so much on the mesh. Although not really needed, we wire brushed everything in case there was loose rust or scale. We then sprayed a thin coat of rust converter on the few heavier rusted areas. We are now ready for mud.
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Photo 03960 viewsThe stairs were to be a part of an overall remodel enclosing a veranda with modern windows, concrete pavers, and an all-glass commercial double door entry. It was my turn to get in there after the funky brick steps were removed and the old tree stumps chopped out from under the porch. I removed the wimpy, crumbly foundation work seen here so I could pour my own fortified foundation. I needed a good footing under the porch to counteract the cantilevered steps, steps that were to not touch the ground visibly. The plan was to dramatically light the completed stairs from below revealing a bed of smooth beach pebbles under them.
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Photo 14953 viewsUsing a level and tape measure I carefully tack welded each step to each bracket with little vertical pieces of 3/16th, being careful to get each step leveled left to right, tilted forward 1/4" in 12" (for water runoff), and exactly 7-1/2" above one another. I also filled rod in under the ends of each. I can still stick weld rod faster than Benihana can chop meat at your table, but this work had to be exact.

Last additions - Ted's Gallery
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Photo 291593 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 281565 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 261354 viewsDoes this look like bliss or purgatory? I was singing and soaring withnature's forces.Feb 01, 2005
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Photo 271682 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 241272 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 251162 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 231334 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 221278 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