Concrete Cooling

Although I have heard of this, I have never seen it done. Nor have I seen this in any specification. At any rate your question cannot be answered with the information given. The initial temperature and mass must be known. Additionally you would have to factor in the heat of hydration of the concrete which will not be constant as the more the ice melts the more water will become available for the reaction.

The total volume by weight of any mix water plus the ice can not exceed that given in the mix design in order to maintain the specified water cement ratio. Not to mention that all of the ice must be melted and thoroughly mixed before placement. So many elements to control that potentially could affect the quality of the concrete, no wonder I've never seen it in a spec. AND; ten degrees C, well thats colder than I've ever seen any concrete.

Thank you for the information. This is not mentioned in the specification. It is only mentioned that the placing temperature of concrete should be within 10-20 degree C. But the only method of cooling is by replacing water with ice flakes. i.e. pre-cooling or any other method is not employed. Can you please tell me up to how much percentage of cement (both OPC & PPC) can be replaced by flyash and microsilica in order to reduce the heat of hydration without reduction in strength. What admixture will you suggest to reduce the heat of hydration? How much percentage will it reduce? It will be very much helpful to me.

An estimate might be calculated if the initial temperature and "specific heat" of all ingredients is known as well as the weight of each. Heat gained by the ice equals heat lost by everything else as it approaches equilibrium. In practise, experiment will show the way. Substitute ice for batch water, pound for pound, in increasing amounts with successive batches and monitor the final temperature of the mix in place.

One caution - all the ice MUST be melted before mixing is complete, or the strength of the concrete may be compromised!

Thank you for the valuable information. The initial temperature of the aggregates and cement etc. will be about 'T' degree centigrade. Assume specific heat of cement, flyash, fine aggregate and coarse aggregate as 'a','b','c' and 'd' respectively. Quantities are 'Q1','Q2', 'Q3' and 'Q4'. Then what will be the heat liberated? And what should be the temperature of batch water which is substituted for ice? Can you suggest any admixture which will be effective in reducing the heat of hydration? It will be very much helpful if you can help me out. Thank you.

I do no know why the concrete temperature must be between 10^o and 20^o C (50^o to 68^o F). For most U.S. specifications maximum concrete temperature is 38^o C (100^o F). Concrete is not to be placed if the ambient temperature is 7.2^o C (45^o F) and falling, to assure freezing temperatures do not occur during the first 24 hours of the cure period.

The maximum temp. is to provide some assurance that the concrete does not flash set during placement. Even at the lowest allowable ambient temp. (7.2^o C, 45^o F), I have not seen the temp of delivered concrete below 20^o C (68^o F). Perhaps you are not interpreting the the specification correctly.

The temperature range of 10^o and 20^o C (50^o to 68^o F) sounds more like the requirement for curing test specimens than for concrete placement and curing. It would be interesting if if you could provide an excerpt from the standard you are using; along with the title and number. I'd very much like to see where these tight restrictions are specified.

I would like to clarify this point that the concrete "placing temperature", during hot weather conditions should be in between 10-20 degree centigrade. And during cold weather conditions, it should not be less than 10 degree centigrade (to avoid freezing). (The only method suggested is partial replacement of water with ice flakes). Apart form this there is no other data given. Cement used is PPC, fylash (of any class) content is restricted to a maximum of 20%. Aggregates are of specific gravity 2.7 Maximum climate temperature of this place (Bhutan) is around 23 degree C. Please suggest a procedure to both hot and cold weather conditions. Please ask if any data is missing. Thank you.