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RE: Match Temperature curing

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If match temperature curing is critical, you must write your own
specification.  You need to provide for a thermostatically temperature
controlled curing box for your samples.  

The next question is how to control and monitor the temperature of the in
place sections.  It is best to use thermocouples at various depths and to
control the section temperature as best you can by using insulating blankets
and insulated forms.  It is essential to minimize the thermal gradient.  

Once the thermal gradient is minimized.  The section temperatures can be
monitored and the ambient temperature of the curing box can be adjusted to
mimic the section temperature.  This is best done by automatic electronic
controls.  

If automatic electronic controls are not possible, the operation can be done
by monitoring the thermocouples at specified periods.

It has been some time since I required this on a project.  You should
contact the testing agency to see what their capabilities are.  

Harold Sprague
The Neenan Company


-----Original Message-----
From: Kho Poh Teck [mailto:ptkho(--nospam--at)pc.jaring.my]
Sent: Monday, September 21, 1998 7:58 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Match Temperature curing


It's true that for mass foundation construction MTC may not be warranted
however
there are instances where the cycle time is crucial in order for a section
to be
loaded at a "mature" age( relatively young). Surely the curing and strength
of
cubes need to be accurately determined particularly in element where a large
difference in equivalent volume/thickness between the cast section and the
test
cubes exist. Question is, how do you monitor and control the temperature of
the
samples to mimic temperature of the section. ?

Regards
KHOpt
CEng

Harold Sprague wrote:

> Match temperature curing is often specified for field cast concrete in
which
> the temperature of the samples (cubes or cylinders) are kept at the same
> temperature as the concrete section that was cast.  Curing and strength
are
> time and temperature dependent.
>
> Match temperature curing is best accomplished by covering and placing the
> samples near the concrete section that was placed.  If cold temperatures
are
> anticipated, the samples should be placed under the same blanket to more
> accurately mimic the curing temperature (trapped heat of hydration) of the
> concrete section.
>
> But often, construction operations preclude this practice.  In that case
the
> temperatures of the samples should be monitored and controlled to mimic
the
> temperature of the section.
>
> The primary issue is curing retardation and slow strength gain due to cold
> weather.  If the temperatures are moderate and the concrete is not that
> critical (foundations), it is generally not worth the effort.
>
> Depending on the cement content, forms (insulation factor), the size and
> shape of the section (thermal mass); the thermal gradient within the
section
> can vary by more than 50 degrees.  Sometimes we delude ourselves.
>
> Match temperature curing is not always accurate or necessary.
>
> Regards,
> Harold Sprague
> The Neenan Company
>
> -----Original Message-----
> From: Kho Poh Teck [mailto:ptkho(--nospam--at)pc.jaring.my]
> Sent: Sunday, September 20, 1998 4:59 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: Match Temperature curing
>
> Can anyone let me know what is "match temperature curing" for concrete?
> I do not think it's merely having test cubes cured on site condition to
> simulate the actual element in question. If not, how would one know
> exactly the maturity of concrete .
>
> Thanks in advance
>
> KHO PT
> CEng
>