PPC cement, coarse aggregate ( mixture of 3/4 th inch & 1/2 inch downgraded stone chips), fine aggregate (coarse sand), and admixture (MasterPolyheed) is used for this construction.
Fresh density is kept above 2.4 gm per cc. The hardened density requirement is above 2.35 gm per cc.
Ice is being used to decrease the mixing water temperature. (To avoid hairline crack in the future)
Key concern is to avoid radiation leakage.
The rooms are being constructed in the basement with wall thickness of 5 to 8 feet and slab thickness of 4 to 8.5 feet. Rooms will be used for Oncology treatment and/or Tomotherapy.
make sure the concrete is mixed and poured properly, then vibrated (to get the bubbles out). During pouring, have some samples poured into small plastic containers for laboratory analysis for elemental composition and mass density. Of course, the shielding survey measurements will be very important ...
In addition to Dr Newhauser's comments, here are some other considerations:
Use high density coarse aggregates, for eg, granite in place of limestone
High workability of concrete and sufficiently spaced reinforcement
Monitoring and controlling heat of hydration during casting and subsequently. Cement replacement materials like fly ash and silica fume are good choices as they not only decrease the rate of hydration, but have filler properties resulting in fewer pores in the matrix.
Sufficient shrinkage reinforcement
Substantial and sustained curing
Hi,
I cannot stress the importance of vibration enough! We had a contractor who didn't, this resulted in visible honeycombing and a huge mess to fix...
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