4. SYMBOLS
Mdo: mass of dry specimen before immersion in water before freezing, in grams.
Mso: mass of saturated specimen after immersion in water before freezing, in grams.
Mho: apparent mass of the specimen immersed in water before freezing, in grams.
Mdn: mass of dry specimen after n cycles, in grams.
Msn: mass of saturated specimen after n cycles, in grams.
MHN: apparent mass of the specimen submerged in water after n cycles, in grams.
VBO: apparent volume of the specimen before freezing, in milliliters.
VBN: apparent volume of the specimen after n cycles, in milliliters. DVb
the variation of apparent volume of the specimen, in%. Eo
: modulus of elasticity of the dry specimen before freezing, in megapascals.
In: modulus of elasticity of the dry specimen after n cycles, in megapascals. DE
the variation of modulus dynamic, in%.
5. EQUIPMENT
5.1 A Frost chamber of sufficient capacity to contain the number of samples required, with an optional automatic control system for programming cycles of freezing and thawing on the camera. Accuracy + -1 ° C.
5.2 A system for recording temperature with an accuracy of ± 0,1 º C.
5.3 A device for measuring the dynamic modulus.
5.4 A weighing instrument with a precision of 0.01% of the mass-weighed.
5.5 A convection oven that maintains a constant temperature of 70 + -5 º C.
6. PREPARATION OF SPECIMENS 6.1 Sampling Sampling is not the responsibility of the test, unless requested.
identification for the test should be selected at least 7 specimens, which must be representative of the entire test piece.
is one of the probes used to monitor core temperature.
for technological tests the number of samples should be appropriate with respect to the relevant standard (Table 1). It will take 2 sets of specimens, one for testing after subjecting them to cycles of freezing and thawing, and the other for testing without subjecting cycles. You can use an extra probe to monitor the temperature of the specimens.
Summary of the application of ice melting test.
NOTE1 _Tamaño according to EN 123720
NOTE 2 NOTE 3 _30mm
_The number of specimens is based on the presence of any feature
Note4 _Tamaño anisotropic according to the standard 1926.
6.2 Size of the specimens. 6.2.1 Test
technology (Test A)
When conducting a study to determine the effect of ice thaw cycles on the performance characteristics ko une eg 12372, the specimens shall be in accordance with the relevant standard. 6.2.2
identification test (Test B) the specimens have the shape of rectangular prisms with the following average, 50x50x300mm. The longitudinal axis must be parallel to the axes of anisotropy.
6.2.3. Marks and reference available on the specimens. To ensure that the different measurements of dynamic modulus before and after ice thaw cycles are performed at the same points on the test specimens shall be indelible marks in the form of half-points on the faces of the specimens.
indelible It drew a line in the axis point of support on which placed the samples for the determination of dynamic modulus.
. 6.3
core temperature monitoring.
On a specimen of each set of specimens will be placed a device (eg a thermocouple) to measure the t th of the specimen during the freeze-thaw cycles. The device should be placed in a hole whose axis is parallel to the longitudinal axis of the specimen. The diameter of the drill has to be appropriate for the diameter of the device. The center hole must be equidistant from the edges of the cylinder to a minimum depth of 50mm from the top. If buckets are used, the drill must have a depth of (25 ± 5). The device be placed in the hole, which is left unfilled.
6.4 Drying of the specimens
The specimens will dry to a t th of (70 ± 5) till constant mass is assumed to be achieved constant mass when the difference between two consecutive weighings at an interval of (24 ± 2) h does not exceed 1% of the first of the two masses. Measurement of dry specimens is the initial value M0. If the specimen will be used for an identification test was carried out modulus measurement, the measurement taken at this time be considered as initial value E0.
6.5 Immersion of the specimens.
specimens are placed vertically in a separate container 15 mm of the adjacent samples. A running water is then added to a t th of 20 th to half the height of the specimens t0. At t0 + (60 ± 5) minutes, adding hot water to reach three-quarters the height of the specimens. The t0 + (120 ± 5) minutes is added to tap water until the specimens are completely submerged under a layer of (25 ± 5) mm of water, left and 48h.
If the specimens are used in an identification test carried out measurements of the apparent mass submerged in water and air mass (the specimen is dried after removing the water.) These measures constitute the initial values \u200b\u200bMh0 and MS0.
6.6 Number of cycles
technological Test 6.6.1 (Test A)
For these the standard specified for Number of cycles to perform
6.6.2 Identification Test (Test B)
The customer specified the maximum # of cycles. If you do not specify a value the test is continued until the specimen is classified as a failure or a maximum of 240.
7. TEST PROCEDURES
7.1 Arrangement of specimens in the chamber of Frost.
The specimens were inserted into the well with the vertical or the horizontal so it does not come into contact with each other or the sides of the camera. Are separated from each 10mm and 20 at least on the sides of the camera The reference specimen containing the measuring device and the t th is placed in the middle of the specimens with no rehearsal.
After every 14 cycles the specimens are rotated 180 ° around the horizontal axis.
7.2 Description of the freeze-thaw cycles.
Each cycle consists of a freezing period in air for six hours followed by a thawing period of six hours in which the specimens were immersed in water. Cycles were repeated until the specimen failure or until you reach the maximum number of cycles prescribed.
changes during the cycle of meetings in the core t monitored the specimen must remain within the area shown in Figure 1.The t th interval allowed is the result of different cooling rates, freezing and thawing related to bulk density porosity and water absorption of the stone tested.
Each cycle should be as follows:
If the T th of the stone is not inside the area, the camera should be adjusted so that it falls into the area and indicate any deviation in the test report. If the test is performed manually, then phase 5 can be extended to 24.0 h. T0 +
identification for the test, you can use different number of cycles and conditions if specified by the customer (see Annex A). Any change in conditions should be reflected in the test report.
-NOTE-It is important that the specimens were thawed in water since it ensures that they are impregnated with water at the beginning of the next process of freezing.
If the test has to be interrupted at any time, for any cause other than the test itself, then the samples will be submerged at all times in water (20 + / - 5 º C). 7.3 Measuring
to determine the resistance to freezing and thawing. 7.3.1 Test
technological
(Test A)
_
7.3.1.1 Visual inspection. It will conduct a visual inspection under par. _
7.3.1.2 7.3.2.1 Other methods (eg, change in resistance to bending). After completing the prescribed number of cycles, the specimens were tested in accordance with the relevant standard. 7.3.2
identification test (Test B) used three criteria to evaluate the action of freeze / thawing on the samples:
· Visual inspection
· Measurement of apparent volume
· Measurement of dynamic modulus (Young's modulus).
control measurements carried out over a period of thawing. At least we need a period of 4 hours to reach the thaw, after the introduction into the water. The specimens immersed again immediately after it carried out the measurements. Visual inspection and measurements of air mass and apparent mass submerged in water was carried out at least every 14 cycles and the dynamic elastic modulus (Young's modulus) at least every 28 cycles.
All results must be appropriately registered.
7.3.2.1_ visual inspection. After the freeze / thaw examine all sides and edges and their behavior be assessed according to the following scale:
0. Intact specimen;
1. minimal damage (rounded corners and edges at least) that does not compromise the integrity of the specimen;
2. one or more small cracks (<ó= 0,1 mm de ancho) o rotura de pequeños fragmentos ( <ó= 10 mm2, por fragmento); 3. una o varias grietas, agujeros o rotura de fragmentos de mayor tamaño que el definido en el pto. 2, o alteración del material en vetas; 4. probeta rota en dos o más grandes grietas; 5. probeta rota en pedazos o desintegrada.
Record the number of cycles with which it achieves the classification 3 (see also 7.3.2.4)
7.3.2.2_ apparent volume measurement. Measuring changes in apparent volume during cycles of freezing and thawing makes it possible to estimate the material losses as a consequence of the deterioration suffered by the specimens.
For each sample, after dipping in water before starting cycles:
weigh the specimen submerged in water and note the apparent mass: Mh0
dried specimen surface with a damp cloth and determine the mass of saturated specimen: ms0
Repeat the same steps to n cycles (MHN and MSN, respectively)
The initial bulk volume is calculated as follows: VB0 = (MS0 - Mh0)
A n cycles, the apparent volume is calculated as follows: vbn = (Msn-MHN)
-NOTE-For test purposes it is assumed that the density of water is 1000 kg/m3
The variation in apparent volume percentage (variation of Vb) n cycles is calculated as follows: Change
Vb = [(MS0 - Mh0) - (Msn-MHN)] x 100 / (ms0 - Mh0)
is considered that the deterioration occurs in a sample where the reduction in the apparent volume reaches 1% of original apparent volume indicates the number of cycles measured by the 1 st time this situation.
7.3.2.3_ dynamic elastic modulus measurement (Young's modulus). By measuring the variation in Young's modulus during freeze / thaw, it is possible to detect some damage such as microcracks. Young's modulus is measured according to the draft European standard prEN 14146.
is necessary to dry the specimen to constant mass (see 6.4) and then perform the measurement.
The specimens were immersed in the water again, according to 6.5 before continuing the cycle of freezing and thawing.
The percentage decrease in dynamic elastic modulus (Young's modulus) is calculated:
(E0 - En) x 100
ΔE =--------
E0
Where
:
· E0: is the initial step, dry (see 6.4) made before starting the cycles.
• In: is the dry measurement (see 6.4) after n cycles.
indicates the number of cycles which makes the decrease of dynamic modulus reach 30%.
7.3.2.4_ Impairment.
The trial will continue until 2 or more specimens are classified as failures, using any of the following criteria:
• The classification of visual inspection reaches the value 3.
• The apparent volume decreased less than 1%.
• The decrease in modulus of elasticity reaches 30%.
8. EXPRESSION OF RESULTS
8.1. Technology trial (Trial A):
The change in the behavior is determined from the individual results by the methods prescribed in the relevant product standards.
8.2. Identification test (Test B):
indicates the number of tests performed, the causes of failure and results of all measurements before failure.
9. TEST REPORT
The test report shall contain:
a) a unique identification number of the report;
b) the number, title and date of publication of this European standard;
c) the name and address of laboratory trial and the address where the test was conducted if different from the testing laboratory,
d) the name and address Customer;
e) is your responsibility to provide the following information:
• the name of the Petrographic stone
• the trade name of stone
• the country and region extraction;
• the name of the supplier;
• the address of any existing plane anisotropy (if relevant to the test) clearly indicated on the sample or on each specimen by 2 parallel lines;
• the name of the person or organization who performed the sampling;
· surface finish of the specimens (if relevant to the test.)
f) the date of delivery of the samples or specimens;
g) the date of preparation of the samples (if relevant) and the date of the trial;
h) the number of samples in the sample;
i) the dimensions of the specimens;
j) for the technology trial:
percentage of variation in behavior as a result of subjecting the specimens to freeze / thaw made, and the number of cycles;
or for the identification test:
the maximum number of cycles required by the client, and number of cycles carried out before damage occurs.
k) a statement of measurement uncertainty (where applicable);
l) any deviation from the norm and why;
m) observations
The test report shall include the signature (s) and position (s) of those responsible for testing and the date of issuance of the trial. It will also provide that the report may not be reproduced in part without the written approval of the test.
ANNEX A (Informative)
For certain specific uses may be appropriate to use different test cycles, for instance, freeze water, freeze at a lower temperature and testing of the specimens embedded in non-porous silica beads .
In these cases, you can follow the national standards provided that such changes are clearly established in the test report.
