ASTM C1656-07
(Guide)Standard Guide for Measuring the Reactivity of Hydraulic Refractory Castables using Exothermic Profile
Standard Guide for Measuring the Reactivity of Hydraulic Refractory Castables using Exothermic Profile
SIGNIFICANCE AND USE
The heat of hydration of a calcium aluminate based castable is liberated over a short period of time (as compared to Portland cement). This makes it easy to measure the heat profile using off-the-shelf thermocouple equipment.
The heat profile can be used to make inferences about the setting and strength gain behavior of a castable and sometimes the working time of a castable.
Factors that should be controlled when comparing two castables include: size, shape and mass of cast object, start temperature of the mix, temperature of environment, and the thermal conductivity of the environment. If these factors are held constant, then the two castables heat profiles can be compared.
The amount of heat rise created by the castable shall be a minimum of 5°F. If this is not achieved, then either a larger sample or better insulation (or both) should be used to increase the measurable heat release.
Varying the amount of cement in the castable, the amount of water, the type and quantity of admixtures, and so forth, will change the shape, maximum temperature and time to maximum temperature of the curve.
Following is an example of a curve generated for an LCC (see Fig. 1) that does exhibit two peaks, the first one marking the end of working time. In this curve one could also infer that the start temperature of the mix was 24°C and also that the hydraulic strength gain reaction was significantly started, but not completed by 6 h.
FIG. 1 Example of LCC Exo Profile
SCOPE
1.1 This guide applies to all castables with a reactive binder system that produces a measurable heat profile during the setting and hardening process. The majority of these systems will have calcium aluminate cement as one component of the binder system.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C1656 −07
StandardGuide for
Measuring the Reactivity of Hydraulic Refractory Castables
using Exothermic Profile
This standard is issued under the fixed designation C1656; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 The heat profile can be used to make inferences about
the setting and strength gain behavior of a castable and
1.1 This guide applies to all castables with a reactive binder
sometimes the working time of a castable.
system that produces a measurable heat profile during the
setting and hardening process. The majority of these systems
4.3 Factors that should be controlled when comparing two
will have calcium aluminate cement as one component of the castables include: size, shape and mass of cast object, start
binder system.
temperature of the mix, temperature of environment, and the
thermal conductivity of the environment. If these factors are
1.2 This standard does not purport to address all of the
held constant, then the two castables heat profiles can be
safety concerns, if any, associated with its use. It is the
compared.
responsibility of the user of this standard to establish appro-
priate safety and health practices and to determine the
4.4 The amount of heat rise created by the castable shall be
applicability of regulatory limitations prior to use .
a minimum of 5°F. If this is not achieved, then either a larger
sample or better insulation (or both) should be used to increase
2. Referenced Documents the measurable heat release.
2.1 ASTM Standards:
4.5 Varying the amount of cement in the castable, the
C401 Classification of Alumina and Alumina-Silicate
amount of water, the type and quantity of admixtures, and so
Castable Refractories
forth,willchangetheshape,maximumtemperatureandtimeto
C71 Terminology Relating to Refractories
maximum temperature of the curve.
C862 Practice for Preparing Refractory Concrete Specimens
4.6 Following is an example of a curve generated for an
by Casting
LCC (see Fig. 1) that does exhibit two peaks, the first one
marking the end of working time. In this curve one could also
3. Terminology
infer that the start temperature of the mix was 24°C and also
3.1 Definitions:
that the hydraulic strength gain reaction was significantly
3.1.1 EP – exothermic profile, n— the curve generated by
started, but not completed by 6 h.
plotting temperature of the embedded thermocouple versus
time.
5. Apparatus
3.1.2 LCC, n—Low cement castable
5.1 Mixing equipment as prescribed in C862.
5.2 Type T thermocouple (Type J, E, or K are also accept-
4. Significance and Use
able but not preferred due to range of sensitivity. Other types
4.1 The heat of hydration of a calcium aluminate based
cannot be used.) Wire ends should be joined by solder or
castable is liberated over a short period of time (as compared
welding. Simple twisting is not recommended due to the
to Portland cement). This makes it easy to measure the heat
potential for inaccurate readings.
profile using off-the-shelf thermocouple equipment.
5.3 Thermocouple sheathing (optional)
5.4 Voltmeter, data acquisition card or some other instru-
ment to read the thermocouple mV value.
This guide is under the jurisdiction of ASTM Committee C08 on Refractories
and is the direct responsibility of Subcommittee C08.09 on Monolithics.
5.5 Container for storage of castable during heat profile
Current edition approved March 1, 2007. Published April 2007. DOI: 10.1520/
generation and constant temperature environment in which to
C1656-07.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or store the container.
contact ASTM Customer Service
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.