We are currently working on a proje
We are currently working on a proje
(OP)
We are currently working on a project which will require a mat foundation approx 2m deep x 4m wide x 12m long.
At what point, as a rule of thumb, should we worry about heat of hydration causing unwanted cracking in the foundation (various publications state anything greater than 1m in depth can be problematic - we are looking for practical recommendations). Also, what measures can be taken to combat this situation (ie: different portland cement in the mix, insulating to protect heat loss and maintain temperature differentials, etc.)
Any guidance is greatly apprecieated.
dutchie
At what point, as a rule of thumb, should we worry about heat of hydration causing unwanted cracking in the foundation (various publications state anything greater than 1m in depth can be problematic - we are looking for practical recommendations). Also, what measures can be taken to combat this situation (ie: different portland cement in the mix, insulating to protect heat loss and maintain temperature differentials, etc.)
Any guidance is greatly apprecieated.
dutchie






RE: We are currently working on a proje
I once placed a large mat - 23' x 23' x 12' (7m x 7m x 3.65m) and we specified chilled aggregate, temperature monitoring, water curing, etc. You can vent the mat and do a number of other things to control the heat.
RE: We are currently working on a proje
Type IV cement is a slow hydrating cement for control of temperature in large pours. Also admixtures for the retardation of hydration are available, check with local concrete plants for types and availability.
Here is good paper that may help:
http://matse1.mse.uiuc.edu/~tw/concrete/prin.html
RE: We are currently working on a proje
RE: We are currently working on a proje
FDOT also requires the contractor to hire a specality engineer to design the temperature control plan per ACI 207. Although I don't recall the number, I thought the "mass" threshold is a function of the volume divided by the surface area.
Hope this helps.
RE: We are currently working on a proje
Wow! I have never heard of insulating concrete in Florida! I suppose insulation would prevent too rapid of a temp. rise in a hot climate, air temp 110, concrete temp. 95? I'm used to insulating up here in snow country!
RE: We are currently working on a proje
RE: We are currently working on a proje
Replacement of OPC with PFA also reduces the heat produced.
Using a plasticiser to provide workability means the water content can be reduced thereby lowering the cement content while keeping the water cement ratio unchanged.
Chilled water (depending on the ambient temperature) may be an advantage to keep the temperature of concrete at the time of placement to below 30 deg.C
Zambo
RE: We are currently working on a proje
We are on the right track now,
dutchie