Article tools: Share:

Okay, So Tell Me How to Implement the Data…

Jim Baty,
CFA Technical Director

You’ve received your copy of the CFA Cold Weather Research Report, read it cover to cover and now you sit back in your chair and think to yourself…What do I do now? There is an incredible amount of data in our research report, however, like most reports of such a technical nature, even with the best intentions in mind, it is not always crystal clear what the next step should be for immediate implementation.Fortunately, the weather is warming up and cold weather is one of the last things on our minds. It is now the perfect time to begin considering what your plan is for next year’s cold weather needs. Let me suggest a few ways to make our report impact your decisions for those plans.

Let’s begin with the very basic first step. At the end of the report,there are a series of pages providing summaries of the results and recommendations for contractors, concrete suppliers and code officials. It is in everyone’s best interests for you to develop a thorough understanding for the performance of the concrete that will be used during cold weather conditions and the imperative details for consideration in practicing good cold weather concrete. Following these guidelines, the performance of most mix designs can already be proven successful.

The next step in the process is to understand the mixes that you currently work with and what, if any, modifications you should make to your plans for mix designs for varying conditions. This is perhaps a bit more detailed of a step at first glance, however, with the effort that has been produced to this point and the results stemming from the three year program summarized in the report, you have a distinct opportunity to quickly validate the anticipated performance of your own mix designs. This is the real meat of our research that you should strongly consider employing through these next couple of months.

A great start begins with your ready mix supplier. The partnership that can be created between the professional that creates the mix and the professional that creates the wall can be a major key to the success of cold weather concrete foundations. It is the business of the ready mix supplier to know the performance of concrete mixes and the maturity that should be expected from a given mix. Although there are 36 mix designs that you could produce from our models, they may not be the most economical for your market or may not reflect specific components that are delivered economically to you. For this reason, an analysis of the mix designs you douse, or your producer does recommend, should take place.

Analyzing a mix design without going through the extensive submission to cold or frozen temperatures takes place with the aid of a maturity pro Maturity testing with a computer allows you to extrapolate the data from these standard cylinder breaks to other temperatures. For instance, from the research completed we can deduce that concrete does indeed cure at cold temperatures, albeit slowly, as long as it does not freeze. Once it freezes, curing stops and as long as the maturity has reached approximately 500 psi before that point, there will be no significant or appreciable impact to the concrete. We also know that the maturity system accurately tracks the strength gain rate. We showed that if cylinders are cured at warmer temps (our research used 50F but it works at any temp within reason) the maturity curves remain valid and especially so at low concrete temperatures. Therefore, if you have cylinder breaks made at 70°F, then you create a maturity curve based on that temperature. This information is then introduced into the maturity system in the field where ambient temps, for instance, may be in the 15-20°F range, the system would accurately predict the strengths attained during those actual conditions within an acceptable margin of error for such low strength concrete.

However, remember that what we are talking about is concrete temperatures. At a concrete temperature of 10°F the concrete will absolutely be frozen and thus worthless if it hasn’t first reached the approximate minimum maturity of 500psi. But at an ambient (air) temperature of 10°F (or lower, even) the internal concrete temperature may be more like 33-35°F. A key statement to this fact in the report is that ambient temperature really means nothing or very little if anything other than the setting the base for drawing heat from a warm body like our concrete at a given rate.

There will be temperatures at which you cannot place concrete, or at least you should not place concrete. There are mixes that have been proven to perform at sub-zero ambient temperatures yet we all know that it is not to our advantage as owners to push our crews to that level of performance. Still, armed with this information, change can occur.

An example of this success has been found recently in Anchorage, Alaska. From the report, you can see the extensive protection systems that this market was forced to employ at very conservative ambient temperatures. Through the efforts of our research, a very concerned builder, CFA foundation contractor and a local HBA representative, the information from the Cold Weather Research Report was presented to the local jurisdiction. Let me quote the builder in that market from a recent email to the CFA Headquarters:

Just wanted to let you guys know that we now have a new policy in Anchorage. We can now place Mix # 29 and # 34 down to 20 degrees F with no tenting or heat. We are replacing calcium with nonchloride accelerators (NCAs). This a dream come true. My last tent that I did last April, when it was 35 degrees out, cost about $2,700. What a waste! We definitely have been brain washed about this matter for way too long. Thanks again for all your hard work.

Can you be successful employing this process in your local jurisdiction? Absolutely! Will it take extensive efforts on your part to provide the information necessary and the proof that your mix designs, or those from our research will work? Very likely not. I encourage you to dig into this report. Contact CFA Headquarters to discuss its application to your market. Touch base with key individuals from the research team like Brad Barnes, Terry Lavy and John Gnaedinger. This is a great example of the impact membership in our Association can have on your business and it is up to you to put it to work for you.

GOOD LUCK AND HAPPY COLD WEATHER CONCRETING.

Comments are closed.

Get Connected

Like us on Facebook Connect with us on Concrete Foundations CFA Members Connect with us on CFA Members

Archives

About Us



Concrete FACTS, a publication of the Concrete Foundations Association, is THE voice for residential concrete industry news, market intelligence, business strategies, technical solutions, product information, and other resources for professionals in the cast-in-place concrete industry. Subscriptions to Concrete FACTS is available to anyone involved or interested in the residential concrete industry as a service to your industry. Please contact CFA Headquarters to find out more about your free subscription or Email Us