TURBOnews November / 2016
Optimizing the precast production with warm concrete
Curing of precast concrete products is highly dependant on the temperature of the poured concrete and the environment. High concrete temperatures accelerate the hydration while low temperatures slow it down.
It is a well-known fact that the hydration stops at concrete temperature of approximately 5 ºC [41 ºC]. In fact, the rate of hydration doubles with a temperature increase of 10 ºC [18 ºF] (Precast.org/NPCA and others).
By controlling and increasing the initial concrete temperature the production process benefits from shorter curing times and thus becomes faster, more efficient and productive.
The higher concrete temperature speeds up the curing process remarkably and stabilizes the concrete quality of the production; the same water-to-cement ratio brings expected strength in a shorter curing period.
For production of precast concrete these facts are indeed the key factors to a faster working cycle and stable quality in the end product. Studies show that a concrete temperature of 25-28 ºC [77-82 ºF] provides the fastest hydration process. Achieving this with Polarmatic!&s technology today is not only easy but also affordable.
In order to produce concrete warmer than 18 ºC [64 ºC] in ambient temperature of less than 10 ºC [18 ºF], to heat the batch water only will not be sufficient, the aggregates must be heated as well.
Benefits of using warm concrete:
- Faster rate of hydration – faster achievement of required strength to strip the molds
- Lower production costs per mold due to higher productivity. While the curing times are dramatically reduced, the same personnel and production line produces more in the same time.
- Higher and more stable quality due to homogenous temperature in slab: no more cracking plus predictable strength development - thanks to controlled temperature.
- Reduction of cement in concrete due to better control of w/c ratio: predictable curing times allow the producer to use mix designs with less safety margin. Less variation in concrete temperatures makes the curing so much more predictable.
- Savings in energy: it is much more energy efficient to heat the concrete instead of heating the curing chambers excessively. Shortened curing times also cuts costs on heating chambers or molds.
All this can be achieved with the TURBOMATIC™ heating system with a superior Return-On-Investment (ROI). Thanks to these benefits highlighted above, a typical ROI of a TURBOMATIC™ heating system is calculated in months – not years. Contact your Polarmatic representative for tailored calculations.
Development of Concrete Strength
Comparison of curing times with different concrete temperatures.
Polarmatic’s solution is the TURBOMATIC™ heating system. This one single thermal energy unit provides the heat energy required for all consumers in the factory:
- Warm concrete production (warm mixing water, warm aggregates)
- Warm water for wash-out or other purposes
- Radiant/convective (hot water) or TURBOsteam curing
- CUREMATIC™ curing control
- Facility heating of all kinds
We always offer a tailored solution that covers one or several of the different heating needs.
Last exhibitions and events for 2016 – be prepared for 2017
We would be glad to meet you at one of the following exhibitions and events to discuss with you the latest developments and show you the newest Polarmatic products.
Do not miss these important dates still this year:
- Nov. 3 Betonipäivät Helsinki, Finland
- Nov. 5-8 ConMin 2016, Tehran, Iran
- Dec. 6-9 ICCX Russia 2016, St. Petersburg
- Be prepared for next years' big event in Las Vegas – CONEXPO-CON/AGG 2017
Please feel free to contact us if you wish more information about the events we are participating and check our homepage www.polarmatic.fi for detailed information where to find us.