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Unique Dome Structures Use KIM

11th Jan 2016 Concrete Waterproofing, Kryton Buildmat Co. Pvt. Ltd. by M. Kumaravel

The innovation around design continues to push the advent of new technology further and further. The weird and wacky concrete shapes we see popping up all over the world cannot be done with conventional methodology. Thus, the popularity of spraying concrete or shotcrete has been growing at an exponential rate.

IMG_20150912_121546One of the issues with the sprayed concrete method is in ensuring a watertight structure. Conventional waterproofing methods like an external membrane are risky insofar as they can break and tear when the shotcrete is sprayed on top of them. Therefore, internal membranes or admixtures are used to ensure a watertight structure without sacrificing the efficiency of the shotcrete placing method, as well as the ability to innovate with a structures’ shape and design.

An example of this is with an NGO in Chennai, who used Kryton’s Krystol Internal Membrane (KIM) concrete waterproofing admixture in a uniquely designed dome-shaped structure. The domes will be used as guest houses in the Sri Rama Rajya Trust campus. The dome will be 32 feet in diameter with 12-foot peaks and 1-foot stem wall. The foundation was raised as a ring beam about 3 ft from ground level, as the dome was in a low-lying area from 3 ft deep where the hard surface was reached.

A raft foundation was built connecting the base of the ring beam as a measure against earthquakes.  The dome as a whole would supposedly move as a unit when an earthquake struck, allowing the tectonic movements to appear underneath, instead of being subjected to the shear stress that would cause most other construction to cave in.

IMG_20150912_121420The dome was anchored on the floor appropriately to be able to withstand heavy up thrusts (a little over a quarter of a tonne) experienced by dome inflation. Once the anchors are tight in place and sealed, the dome inflated from 6″ to 8″ of H2O level air pressure compared to outside pressure.  This would leave the dome with the stiffness of a football and be able to carry at least a tonne of concrete load.

Concrete using KIM waterproofing admixture was initially sprayed and later towelled in layers from the bottom to close the dome and ensure a watertight seal.  The door and window openings were marked and left untouched. The middle layer of the shell was interspersed with XPS (Extruded Poly Styrene) in the form of foamcrete to a thickness of 3″ in order to allow thermal insulation. After initial curing, the external shell was densified with a densifier to reduce porosity and allow for a smooth finish.

The initial trial dome was a success, resulting in a more economical and simplistic method of construction. The team will be moving forward constructing 150-200 more domes in the coming year using the same methods of concrete waterproofing as done during the trial dome using KIM as the concrete waterproofing solution.

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