Click on the photo to enlarge it. Please scroll down to view the Questions with their Answers.
Q: What makes your panel concrete so crack resistant?
A: The panel concrete is a special formulation containing synthetic fibers and liquid admixtures. These ingredients improve the concrete’s characteristics, create super toughness, extend durability, make concrete impervious to water, give higher tensile and compressive strength, provide elasticity for expansion, and improve freeze protection. The concrete in your dome out performs other exteriors because of its specially developed formula. Because of its exceptional composition, it actually gains strength over the years. The exterior panel concrete adheres directly to the steel mesh and the E.P.S. insulation without the need of a bonding agent.
Q: I understand when I mix concrete on site to fill the panel seams; the recipe includes the same liquid admixtures and fibers that American Ingenuity used in the panel concrete. Is this true?
A: Yes, Ai ships the same liquid admixtures and synthetic fibers with the Building Kit so the seam concrete that is mixed on site in a mortar mixer not a cement mixer will have the same properties as the panel concrete that was applied at the Ai plant. Fibers in concrete work to reduce the formation of shrinkage, (cracks in concrete’s plastic state) while helping to improve shatter resistance and reduce water migration. The result: tougher concrete.
The liquid admixtures shipped with your dome kit are marked A and B. One is an air entrainment and the other is a water reducer.
The Concrete Mix recipe includes water, 1 bag Portland Cement (type 1 or 111), Admixture A, Admixture B, ¼ large bag fibers, Sand (called masonry or stucco sand….no rocks). The Assembly Manual includes the precise amounts for each of these items, and when to apply the admixtures. During the assembly of the dome kit, the seam areas between the panels are filled with the special concrete in two applications. In between the two applications of bonding agent, that is shipped with your kit, is applied on the first coat of concrete and onto the bonding ledge of each panel before the second coat of concrete is applied. Prior to the second layer of concrete being applied, decide the seam appearance, flat or curved. The second layer is sponged so that its appearance is a “sponged sand finish” to match the sand finish, which is the finish on Ai’s prefabricated component panels. Prior to priming and painting the concrete allow the concrete to be rained on for one month to remove efflorescence.
Prior to the application of concrete into the seams, all the prefabricated panel concrete or cured concrete around the area to receive the new concrete is watered down. The “Old” concrete is kept wet while the new concrete is curing. Ai’s Assembly Manual explains step by step how to apply concrete in the seams and onto the entryway and dormer panels.
Q: After all the seams between the component panels and building options are concreted, what is used to seal the concrete?
A: Ai does not depend on the concrete to make the dome watertight. The dome is sealed with a concrete primer and two coats of good quality exterior concrete paint purchased locally. Ai dome owners recommend the following paints:
- Richards Paint: Rich Flex 245; use Rich Flex Alkali Resistant 100% Acrylic Masonry Coating for the primer.
- Behr’s top of the line exterior latex paint is Marque. Seabrook Texas dome owner loves this paint. He uses semi-gloss. Marque has the most titanium in the Behr’s line. – Home Depot
- Sherwin Williams: Loxon XP Paint, Loxon Primer and Conditioner
- Behr’s Premium Elastomeric Masonry, Stucco & Brick Paint –Home Depot
- Seal Krete Paint (pigmented) –Home Depot
- Ames Research Labs: Maximum – Stretch, at participating ACE & True Value Stores or can be purchased directly from Ames at 888-345-0809 (if using Ames paint, specific type sealants and primer need to be used. TT3 sealant cannot be used.)
Q: I am considering applying elastomeric paint over the entire dome, should I do this?
A: Yes if the concrete was primed with concrete primer, if the paint is breathable and if interior water vapor is removed from the interior with Broan Bathroom Exhaust Fans, Top of dome exhaust fan, stove/microwave exhaust fans and use of Heat Recovery Ventilator or Energy Recovery Ventilator if needed in your area. Water vapor accumulates in the dome from breathing, doing laundry and dishes, showering and should be removed from the dome.
In northern climates, install a Heat Recovery Ventilator to remove moisture or check with your local HVAC subcontractor for latest solutions. To read about Heat Recovery Ventilators click on HRV.
For an existing dome that has elastomeric paint applied to it, please do not remove the elastomeric paint. Please call our office for the most current painting info for previously painted domes. Phone 321-639-8777 Mon – Fri 9-5 eastern.
Q: What if I get a leak in the dome shell?
A: Generally, it is easier to repair a leak in our concrete dome than it is to make a repair in a shingled roof. Applying EternaBond Tape (has MicroSealant) and textured knife grade patching compound is all it takes to seal the area if the concrete is bonded. Call Ai’s office for more info (321-639-8777).
Q: Where am I most likely to get a leak?
A: Where a passageway connects two domes, what Ai calls a link. A leak most likely will occur where the long flat roof of the link butts up to the curved surface of the dome shell. The expansion and the contraction associated with temperature changes produce the flex or separation at the link. The fall is the most likely problem time. Seal the area where the link meets the dome with the EternaBond Tape and textured knife grade patching compound and elastomeric paint.
Q: Explain why the use of a bonding agent helps prevent leaks.
A: Technology has developed now to prevent cold joints. The Assembly Manual that comes with the American Ingenuity Dome Kit explains how to utilize bonding agent and other techniques to join the concrete in the seams. Concrete, or a cement mixture, will not bond to a dry absorbent surface such as dry concrete. The reason is easy to understand when you examine the curing process of cement. When new concrete is applied over old, dry concrete, the moisture from the new concrete will be absorbed by the dry concrete especially at the surface where they meet. When the new concrete is robbed of its moisture at the joining surface it will not cure properly and therefore will not bond.
Bonding agents are designed to improve the adhesion between layers of concrete by acting as a glue and coating and sealing the dry concrete to prevent it from robbing the moisture.
Q: What else do I do during the seam concreting to assure that the second layer of concrete bonds to the concrete of the panels and to the first layer of the seam concrete?
A: This is discussed in detail in the Assembly Manual, basically, wet the adjacent panels with water and allow them to soak up all the water they will before applying concrete into the seam areas. Plus apply bonding agent on the concrete ledge at the edge of the panel and on any concrete that has been placed in the seam before the second layer of concrete is applied.
Q: What other special features are designed into the panels of your kit to improve the bond and strength of your dome?
A: The pre-concreted panels have a ledge molded into the edge of the concrete where the seam concrete is most needed to bond. This ledge increases the bonding surface, thereby increasing the ultimate strength of the joint. The steel mesh, which extends from the old concrete to the new concrete is a small mesh which compliments the effect of the fibers in securing the joint.
Q: Can I spray concrete into the seams instead of hand applying it?
A: No. Ai does not recommend pumping or spraying the concrete into the dome seams because the equipment usually pumps faster than the seams can be finished. The over spray gets on the panels and unless it is washed off ASAP, it will harden and be difficult to remove.
Q: Why is it more beneficial to have pre-concreted panels instead of spraying concrete all over the dome on site?
A: A continuous sprayed concrete structure will cause the concrete to cure all at once. Pre-concreted panels allow for the panel concrete to cure prior to the seam concrete being applied.
In 1976 American Ingenuity manufactured and then built its first geodesic dome prototype by utilizing reinforced concrete over E.P.S. insulation. Steel mesh was hand tied onto the propped up E.P.S. insulation, concrete was then gunited and troweled over the propped up E.P.S. insulation. Countless designs and manufacturing construction techniques were analyzed in the early years as American Ingenuity developed a new generation in dome housing. Ai has outgrown two previous models as we progressed to a five dome complex.
Ai does not recommend sprayed concrete structures because spraying concrete causes a waste of labor and concrete. The concrete ends up being 2″ thick in one place and 3″ to 4″ thick in other places. The concrete on the dome needs to be thick only in the seams and thin on the panels. It is a waste of labor because it is difficult for the concrete finishers to stand in the concrete and try to finish the concrete as it cures.
Q: What is the curing time for the seam concrete?
A: The weather and the mix of the concrete (amount of water, etc.) will effect the curing time of the concrete. Usually by the time a complete row of panels is placed the next row can be assembled. If a panel is placed above another panel and cracks start to form in the first coat of concrete, then the concrete has not cured long enough. Stop placing panels until the concrete has cured and passes the “scratch test”. Take a nail or screw driver and scratch the concrete if no indentation place the next row of panels.