Some standard content:
Industry Standard of the People's Republic of China
Test Method for Basic Properties of Building Mortar
70—90
Notice on the Issuance of Industry Standard "Test Method for Basic Properties of Building Mortar"
(90)Jianbiaozi No. 693
Construction Committees (Construction Departments) of provinces, autonomous regions, and municipalities directly under the Central Government, Construction Committees of independently planned cities, and relevant ministries and commissions of the State Council:
In accordance with the requirements of the Ministry of Construction and Environmental Protection (86)Chengkezi No. 263, the Test Method for Basic Properties of Building Mortar compiled by Shaanxi Provincial Architectural Science Research and Design Institute has been reviewed and approved as an industry standard, numbered JGJ70-90, and will be implemented from July 1, 1991.
This standard is managed by the China Academy of Building Research, the technical unit responsible for building engineering standards of the Ministry of Construction, and its detailed interpretation and other work are the responsibility of Shaanxi Provincial Architectural Science Research and Design Institute.
Ministry of Construction of the People's Republic of China
December 30, 1990
Main symbols
Mass density of mortar mixture (k/m°)
: A Cross-sectional area of penetration test needle (mm2) N Static pressure when penetration depth reaches 25 mm (N) f. Penetration resistance value (MPa)
·A Pressure bearing area of test piece (mm)
fman Compressive strength of mortar cube (MPa) N. Destruction pressure (N)
Axial compressive strength of mortar (MPa),
Static elastic modulus of mortar (MPa),
Deformation difference of the last load in elastic mold plate test (mm)1
4f. The strength loss rate of mortar specimen after paint melting (%) Amg
The mass loss rate of mortar specimen after freeze-thaw (%) corresponds to the natural drying shrinkage value of the mortar specimen at +. 8n
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 1
Sampling of mixture and preparation of test specimens.
Consistency test·
Density test
Degree of stratification test·
Determination of setting time
Cube compressive strength test
Static compression sieve modulus test
Anti-freezing performance test
Shrinkage test··
Appendix Terms used in this standard
.**.18
Additional notes Who is the editor-in-chief of this standard, the list of participating units and main drafters 21 Chapter 1, General.
Article 1.0.1: This standard is formulated to adopt a unified test method when determining the performance characteristic value of building mortar, inspecting or controlling the quality of on-site mixed mortar.
Article 1.0.2 This standard applies to the basic performance test of building mortar used for construction, plastering and other purposes in general structures of housing construction with cement, sand, mortar and admixtures as the main materials.
Article 1.0.3 When conducting mortar performance tests in accordance with this standard, in addition to complying with the relevant provisions of this standard, it shall also comply with the requirements of the current relevant standards. Chapter 2 Sampling of Mixtures and Preparation of Test Specimens
Article 2.0.1 The materials for building mortar tests shall be taken from the same mixer or mortar transported by the same vehicle according to different requirements. When sampling in the laboratory, they can be taken from mechanically or manually mixed mortar.
Article 2.0.2 When conducting mortar tests during construction, the sampling methods and procedures shall be implemented in accordance with the corresponding construction acceptance specifications. The samples should be collected from at least three different locations, such as the mortar tank, mortar delivery vehicle and mixer outlet at the place of use. The number of samples should be more than 1-2 times the test materials.
Article 2.0.3 When the laboratory mixes mortar for testing, the materials for mixing are required to be transported into the room in advance, and the temperature of the laboratory should be maintained at 20±50°C during mixing. Note: When it is necessary to simulate the molten slurry used under construction conditions, the density of the raw materials for the test should be kept consistent with that of the construction site.
Article 2.0.4 The cement and other raw materials used in the test should be consistent with the materials used on site. If there are lumps in the water mixture, it should be fully mixed and sieved with a 0.9mm sieve. Sand should also be sieved with a 5mm sieve.
Article 2.0.5 When the laboratory mixes mortar, the materials should be weighed and measured. Weighing accuracy: cement, admixtures, etc. are 0.6%; sand, lime paste, clay paste, fly ash and ground quicklime powder are 1%.
Article 2.0.6 When the laboratory uses a mixer to mix mortar, the mixing amount should not be less than 20% of the mixer capacity, and the mixing time should not be less than 2 minutes. Article 2.0.7 After the mortar mixture is sampled, the test should be carried out as soon as possible. The samples taken on site should be manually turned over and mixed before testing to ensure their uniform quality. 2
Chapter 3 Consistency Test
Article 3.0.1 This method is applicable to determining the mix ratio or controlling the consistency of mortar during construction, in order to control the water consumption: Article 3.0.2 The instruments used for the scheduling test shall comply with the following provisions: 1. Mortar consistency meter, consisting of a test cone, a container and a support (see Figure 30.2). The test cone is made of steel or copper, the test cone height is 145mm. The diameter of the cone bottom is 75mm. The weight of the test cone and the rod should be 300g. The mortar container is made of steel plate, the height is 180mm, the inner diameter of the cone bottom is 150mm, the support is divided into three parts: the base and the bracket, and it is made of cast iron, steel and other metals. Second, the steel tamping rod has a diameter of 10mm and a length of 360mm: the end is rounded. Third, seconds, etc.
一Rack test support
Scale
一Control screw
Slurry container
一Energy base
Figure 3.0.2 Sand table paste tester
Article 3.0.3 The consistency test should be carried out according to the following steps 1. Clean the surface of the slurry container and the test cone with a mixed cloth, and gently rub the slide rod with a small amount of lubricating oil, and then wipe off the excess oil on the slide rod with oil-absorbing paper so that the slide rod can Free sliding
2. Load the mortar mixture into the container at one time, so that the mortar surface is about 10mm lower than the container mouth, use the tamping rod to tamp 25 times from the center to the edge, and then gently swing or knock the narrow device 5-6 times to make the mortar surface flat, and then place the container on the base of the consistency meter.
3. Unscrew the brake screw of the test cone slide bar, move the slide bar downward, when the tip of the test cone just touches the mortar surface, tighten the brake screw, make the lower end of the rack rod just touch the upper end of the slide, and point the pointer to the zero point
Concave, unscrew the brake screw, and count the time at the same time. When 108, immediately fix the screw, make the lower end of the toothed measuring rod touch the upper end of the slide rod, and read the sinking depth (accurate to 1mm) from the dial, which is the consistency value of the mortar
5. The mortar in the conical container is only allowed to measure the consistency once. When repeating the measurement, re-sample and measure it.
Article 3.0.4 The results of the density test shall be processed as follows: 1. Take the arithmetic mean of the two test results, and the calculated value shall be accurate to 1 mm; 2. If the difference between the two test values is greater than 20 mm, another mortar shall be mixed and re-measured.
Chapter 4 Density Test
Article 4.0.1 This method is used to determine the mass density of the mortar mixture after compaction, so as to determine the actual amount of each component material in a cubic meter of mortar mixed food. Article 4.0.2 The instruments used for the mass density test shall comply with the provisions of column E: 1. The container is made of metal, with an inner diameter of 108mm, a static quotient of 109mm, a container thickness of 2mm, and a penetration of 1L. 2. The pan balance weighs 5kg, with a sensitivity of 5g. 3. The steel hot rod has a diameter of 10mm, a length of 350mm, and the end is rounded. 4. Mortar dispatcher. 5. Cement mortar moving table with a vibration of 0.85±0.05mm and a frequency of 50±3Hz, 100 seconds. Article 4.0.3 The mass density test of the mixed mixture shall be carried out according to the following steps. 1. First, the mixed mortar shall be tested for consistency according to the consistency test method in Chapter 1. When the mortar consistency is greater than 60mm, it shall be sent by ramming. When the mortar consistency is less than 50mm, the vibration method shall be used. 2. The container weight shall be weighed before the test, accurate to 5. Then put the funnel of the volumetric tube on (see Figure 4.0.3) and fill the volumetric tube with the mortar mixture with a little surplus. The test method is selected according to the thickness.
A funnel
Volume tube
Figure 4.0.3 Mortar Density Tester
When using the tamping method, fill the cylinder with the mortar mixture at one time: make a little surplus, use the tamping rod to tamp evenly 25 times, if the mortar sinks below the cylinder mouth during the tamping process, add mortar at any time, and then knock 5-6 times. When using the dynamic method, fill the cylinder with the mortar mixture together with the funnel on the vibration table for 109, if the mortar sinks below the cylinder mouth during the vibration process, add mortar at any time
3. After tamping or vibration, scrape off the excess mortar mixture at the cylinder mouth to make the surface flat, then wipe the outside of the cylinder clean, weigh the total weight of the mortar and the cylinder, with an accuracy of 5g. Article 4.0.4 The mass density of the mortar mixture (in kg/m*) is calculated using the following formula:
m=mL×1000 (kg/m*)
Wu—m—mass of the container (kg)
m——mass of the container and the sample (kg)
V—volume of the container (L).
Article 4.0.5 The mass density is determined by the arithmetic mean of the results of the two tests, and the calculation is accurate to 10kg/m
Note: The volume of the container can be corrected by using a glass plate that can cover the container cover. Only the glass plate and the container are weighed, and then water at a temperature of 2 ± 5℃ is poured into the container. When it is thin enough to the top, water is continuously added while the glass plate is slowly pushed into the container mouth to cover it tightly. The pressure should be kept tight so that there is no air bubble under the glass plate. Then touch the glass surface and the outside of the cylinder for water, weigh the container dish and the water together with the glass plate (to the nearest 5g). The difference between the latter and the former (in kcal) is the volume of the container (L). 6
Chapter 5 Degree of Separation Test
Chapter 5.0.1 This method is suitable for determining the stability of the internal components of mortar mixtures during transportation and storage.
Case 5.0.2 The instruments used for the delamination test shall comply with the following provisions: 1. The inner diameter of the mortar delamination cylinder (see Figure 5.0.2) is 150mm; the height of the upper section is 200mm, and the net height of the lower section with the bottom is 100mm. It is made of metal plate. The connection between the upper and lower layers needs to be widened to 3~5mm and equipped with rubber gaskets, 50-
- connection,
- bottom
Figure 5.0.2 Mortar delamination tester
2. The amplitude of the cement mortar vibration table is 0.85±0.05mm, and the frequency is 50±3HzE
3. Degree meter, wooden hammer, etc.
Case 5.0.3 The stratification test should be carried out in the following steps: 1. First, the mortar mixture is measured and dispatched according to the test method in Chapter 3; 2. The mortar mixture is loaded into the stratification cylinder at once. When it is full, use a water chain to gently tap 1-2 times at four different places with roughly equal distances around the container. If the mortar sinks below the cylinder mouth, it should be added at any time, and then the excess mortar is scraped off and smoothed with a spatula.
3. After standing for 30 minutes, remove the upper 200mm mortar, pour out the remaining 100mm mortar and mix it in the mixing pot for 2 minutes, and then measure its rollover according to the test method in Chapter 3. The difference in consistency before and after is the stratification value (cm) of the mortar. Note: The rapid method can also be used to determine the degree of stratification, the steps are: (i) according to the third degree test method determination system, (ii) the degree of stratification is fixed on the perturbation, the mortar is loaded into the stratification area once, and stirred for 20s (iii) after the mortar is cooked, the upper 200mm mortar is removed, and the remaining 100mm mortar is placed in the mixing pot and mixed for 2min, and then the degree of stratification is measured according to the third degree test method, and the difference between the two results can be regarded as the degree of stratification of the mortar. However, if there is any dispute, the standard method shall prevail. Article 5.0.4 The results of the stratification test shall be handled according to the following requirements: 1. Take the arithmetic mean of the two test results as the stratification value of the mortar; 2. If the difference between the two stratification test values is less than 20mm, the test shall be repeated. 8
Chapter 6 Determination of setting time
Chapter 8.0.1 This method is suitable for determining the setting time of iodine mortar and plastering mortar with resistance decay.
Section 6.0.2 Equipment used for determination of set time shall comply with the following provisions 1. Sand setting time determination instrument, consisting of test needle, container, platform scale and support (see Figure 6.0.2). Test needle is made of stainless steel, with a cross-sectional area of 30mm. Mortar container is made of steel, with an inner weight of 140mm and a height of 75mm. The most accurate platform scale is 0.6N. The support is divided into three parts: base bracket and operating rod, which are made of cast iron or steel.
Rate 6, 0.2 Schematic diagram of mortar setting time determination instrument 1-adjustment sleeve, 2-adjustment nut, 3-adjustment cap nut: 4-chuck, 6-retracting piece! 6-test, 7-test mold, 8-adjustment nut: 9-pressure gauge seat; 10-accounting curtain; 11-operating rod 12-adjustment rod: 13-stand, 14-column
2. Clock, etc.
Article 6.0.3 The setting time test shall be carried out according to the following steps. 1. The prepared mortar (control mortar thickness of 100±10mm) is placed in the mortar container, 10 below the container, gently tap the container, and the container containing the mortar is stored at room temperature of 20±2℃. 2. The mortar surface exudes water and is not removed. 3. Determine the penetration resistance value. Use a penetration test needle with a cross-section of 30mm\ to contact the mortar surface. Within 10s, slowly and evenly press it vertically into the mortar to a depth of 25mm. Each time the penetration is recorded, the instrument reading N is recorded. The penetration rod is at least 12m away from the edge of the container or any previous penetration position. 4. Under the condition of 20±2'C, the actual penetration resistance value is measured 2h after forming (starting from the mixing period), and then measured every hour until the penetration resistance reaches 0.3MPa, and then changed to measurement every 15min~~ times until the penetration resistance reaches 0.7MPa.
Note: The construction site is measured in the field, and the degree of resistance, maintenance and measurement are the same as on-site. Article 6.0.4 Mortar penetration resistance is calculated according to formula (6.0,4): Ne (MPa)
Wherein, penetration resistance value (MPa): Ng—static pressure (N) when the penetration depth reaches 25mm, A—cross-sectional area of penetration test needle, i.e. 30mm*. The penetration resistance value is calculated to an accuracy of 0.01MPa. (6.0.4)
Section 6.0.5 The penetration resistance value obtained can be used to determine the setting time of the mortar in the following way:
1. Record the time and the corresponding penetration resistance value respectively. Draw a graph based on the relationship between the penetration resistance and time at each stage obtained in the test. From the graph, find the time (min) required for the penetration force to reach 0.5a. This t value is the setting time measurement value of the mortar. Second, when determining the setting time of the mortar, two samples should be taken from one plate. The average value of the two test results is used as the setting time value of the mortar. The error of the second test result should not be greater than 30min, otherwise it should be re-measured. 10
Chapter 7, Cube Compressive Strength Test
Section 7.0.1 This method is suitable for determining the compressive strength of mortar cubes. Article 7.0.2 The equipment used for the compressive strength test shall comply with the following provisions: 1. The test mold is a 70.7mm×70.7mmx70.7mm cube, made of cast iron or steel, and should have sufficient rigidity and be easy to disassemble and assemble. The inner surface of the test mold should be machined, and its roughness should not exceed 0.05mm per 100mm. After assembly, the non-verticality of each adjacent surface should not exceed ±0.5°
2. Ramming rod: a steel rod with a diameter of 10mm and a length of 350mm, the end of which should be ground; 3. Pressure testing machine: a testing machine with an accuracy (relative error of the coefficient value) of no more than ±2% should be used, and its range should be able to make the expected failure load value of the test piece no less than 20% of the full range and no more than 80% of the lower range
4. Steel pads can be placed between the testing machine, the lower pressure plate and the test piece. The size of the pads should be larger than the pressure-bearing surface of the test piece, and the thickness should not exceed 0.02mm per 100mmWww.bzxZ.net
Section 7.0.3. The preparation and maintenance of cubic compressive strength test pieces should be carried out according to the following steps:
1. When making cabinet construction mortar test pieces, place the test piece on the cut cement bricks that have been pre-coated with absorbent paper (the water absorption rate of the bricks is not less than 10%, and the moisture content is not more than 20%). The inside of the test mold should be coated with a thin layer of machine oil or debonding agent in advance. 2. The paper placed on the broken should be newsprint (or other paper that has been glued to the cementitious material). The size of the paper should be large enough to fit the bricks. The four sides of the brick are required to be used. Any brick that has been adhered to cement or other bonding materials on its four vertical surfaces is not allowed to be used again:
Three: Fill the test mold with mortar at one time, and use a tamping rod to evenly insert it in a spiral direction from the outside to the inside for 25 minutes. In order to prevent the low-viscosity mortar from leaving holes after tamping, it is allowed to use an oil knife to insert it along the wall several times to make the mortar higher than the top surface of the test mold by 6 to 8 mm2. Four. When the mortar surface begins to show pockmarks (about 15 to 30 minutes), the protruding part of the mortar will be shaved off along the top surface of the test mold. Five. After the test piece is made, it should be kept under a temperature environment of 20 ± 5 for a period of time (24 + 2 hours). When the temperature is low, the time can be appropriately extended, but it should not exceed two nights. Then the test pieces should be numbered and demolded. After the specimen is demoulded, it should be cured under standard curing conditions until 28, and then pressure test should be carried out;
Six, the standard curing conditions are: (a) the temperature of cement mixed mortar should be 20±3℃, the relative humidity should be 60~80%, (b) the temperature of cement mortar and micro-foam mortar should be 20±3℃, the relative humidity should be above 90% (c) during curing, the specimens should be spaced no more than 10mm apart.
Note, when standard curing conditions are not available, self-heating curing can be used. (a) Cement mixed mortar should be cured under positive pressure and relative temperature of 60~80% (such as in a curing sheath or in a non-ventilated room), (b) Water-based mortar and micro-foam mortar should be cured under positive temperature and keep the surface of the specimen moist (such as in a wet sand pile); (c) Temperature records must be kept during the curing period. In this case, standard curing conditions should be used. Article 7.0.4 The compressive strength test of mortar cubes shall be carried out in the following steps: 1. After the specimen is taken out from the protection site, the test shall be carried out as soon as possible to avoid significant changes in the temperature and humidity inside the specimen. Before the test, wipe the specimen clean, measure the size, and check its appearance. The specimen size is measured accurately to 1mm, and the pressure-bearing area of the specimen is calculated accordingly. If the difference between the measured size and the nominal size does not exceed 1mm, the nominal size can be used for calculation.
2. Place the specimen on the lower pressure plate of the testing machine (the lower pad is already formed), and the pressure-bearing surface of the test should be vertically aligned with the top surface during the test, and the center of the test should be aligned with the center of the lower pressure plate (lower pad) of the testing machine. Start the testing machine, and when the pressure plate is close to the specimen (or upper pad), adjust the ball to make the contact area evenly compressed. The pressure test should be loaded continuously and evenly, and the loading speed should be 0.5~1.5 kN per second (when the mortar strength is 5MPa or less, the lower limit is appropriate, and when the mortar strength is above 5MPa, the upper limit is appropriate). When the specimen is close to failure and begins to deform rapidly, stop adjusting the throttle of the test machine until the specimen is destroyed, and then record the failure load. 7.0.5 The compressive strength of the mortar cube should be calculated according to the following formula N
fareuA
where mu——mortar cube compressive strength (MPa) N. cube failure pressure (N)
A——test piece pressure area (mm).
The calculation of the mortar cube compressive strength should be accurate to 0.1MPa. The arithmetic mean of the measured values of the six specimens is taken as the compressive strength value of the group of specimens, and the mean value is calculated accurately to 0.1MPa.
When the difference between the maximum or minimum value of the six specimens and the average value exceeds 20%, the average value of the four specimens in the middle shall be taken as the compressive strength value of the specimens in this group. 13
Chapter 8 Test of elastic modulus under static compression
Article 8.0.1 This method is applicable to the determination of the elastic modulus (simple elastic modulus) of various types of mortars under static compression. The elastic modulus of mortar measured by this method refers to the loaded secant modulus when the stress is 40% of the axial compressive strength.
Article 8.0.2 The standard specimen for the elastic modulus of mortar is a prism. Its cross-sectional dimensions are 70.7mm×70.7mm and the height is 210~230mm. Six specimens should be prepared for each test, three of which are used to determine the axial compressive strength. Article 8.0.3 The equipment used for the static compressive elastic modulus test of mortar shall comply with the following provisions:
1. The relative error of the test machine indication shall not be greater than ±2%, and its range shall enable the expected failure load value of the specimen to be no less than 20% of the full range and no more than 80% of the full range.
2. The accuracy of the deformation measuring instrument shall not be less than 0.001mm. In the past, the accuracy of the mirror extensometer should not be less than 0.002mm. Article 8.0.4 The preparation and maintenance of the specimen shall be carried out in accordance with Article 7.0.8 of this standard. The unevenness of the test mold shall not exceed 0.05mm per 100mm, and the non-verticality of adjacent surfaces shall not exceed 1. The bottom brick is required to have a flat surface and uniform color. Article 8.0.5 The mortar elastic modulus test shall be carried out in accordance with the following steps: 1. After the specimen is taken out from the maintenance site, it shall be tested in time. Before the test, wipe the specimen clean, measure the size, and check the appearance. The center of the specimen is measured accurately to 1mm, and the bearing area of the specimen is calculated. If the difference between the measured size and the nominal size does not exceed 1mm, it can be calculated according to the nominal size. 2. Take three specimens and measure the axial compressive strength of the mortar according to the following steps: 1. Place the specimen upright on the lower pressure pole of the testing machine, with the center of the specimen aligned with the center of the lower pressure plate of the press, and start the testing machine: When the upper pressure plate is close to the specimen, adjust the ball 14
seat to make the contact balanced.
The axial compressive test should be loaded continuously and evenly, and the loading speed should be 0.5~1.6kN per second. When the specimen fails and begins to deform rapidly, the throttle adjustment of the test machine should be stopped until the test fails, and then the failure load is recorded; 2. Calculate the axial compressive strength of the mortar according to formula (8.0.5) N
where fm is the axial compressive strength of the mortar (MPa), N is the failure pressure of the building column (N), and A is the pressure-bearing area of the specimen (mm).
The axial compressive strength of the mortar should be calculated accurately to 0.1MPa. (8.0.5)
The arithmetic mean of the measured values of the above three specimens is taken as the axial compressive strength value of the group of specimens. If the maximum or minimum value of the three specimens has a difference of more than 20% from the middle value, the maximum and minimum values are included together, and the middle value is taken as the axial compressive strength value of the group of specimens. If the difference between two measured values and the middle value exceeds 20%, the test results of this group of specimens are invalid. 3. Install the instrument for measuring deformation on the specimen for elastic modulus measurement. The instrument should be installed on the center line of the two sides of the specimen when the specimen is formed, and symmetrically at both ends of the specimen. The measuring gauge length of the specimen adopts 1UUL1II1
4. After the instrument is installed, the position of the specimen on the testing machine should be carefully adjusted. The mortar elastic modulus test requires physical alignment (the alignment method is to pressurize the load to 35% of the axial compressive strength, and the difference between the deformation values of the instruments on both sides shall not exceed ±10% of the average value of the two deformations). After the specimen is aligned and qualified, it is continuously and continuously loaded at a loading speed of 0.5 to 1.5 kN per second to 40% of the axial compressive strength, that is, to reach the control load of the elastic modulus test, and then load to zero at the same speed, and repeat the preloading three times (see Figure 8.0.5).
During the preloading process, the test machine and the instrument should be observed to see if they are operating normally. If not, they should be adjusted.
Five, after three preloadings, the fourth loading is performed at the same speed as above. The method is to first load the initial load of 0.3MPa, hold the load constant for 30s, read and record the measured values of the instruments on both sides, then load the control load (0.4fme), hold the load constant for 30s, read and record the measured values of the instruments on both sides, and the average value of the measured values on both sides is the deformation value of this test. Unload to the initial load at the above speed, hold the load constant for 3.0S, read and record the initial measured values on the two measuring instruments, and then load the fifth time according to the above method, hold the load constant, read the values, and calculate the deformation value of this test. When the difference in deformation values between the two tests is no more than 0.0002 of the measuring gauge length, the test can be ended. The above process should be repeated until the difference in deformation values between the two adjacent loadings meets the above requirements. Then remove the instrument and apply load at the same speed until failure, and obtain the prismatic compressive strength of the specimen fe.
Preloading method
u4th time5th time
Compression specimen failure
Central time!
"Until the test bucket is broken
End of the test
Figure 8.0.5 Elastic modulus test loading system diagram 8.0.6, the elastic modulus value of the mortar should be calculated according to the following formula: Na4-N:
E—Mortar elastic modulus (MPa.).1
N.—Stress is.4tm pressure (N);
N. Initial load with stress of 0.MPa (N)
A Pressure bearing area of specimen (mm2);
A! The average value of the deformation difference between the two sides of the specimen when the stress is increased from V to N for the last time (mm)
Measurement gauge length (mm).
The calculation result of elastic modulus is accurate to 10MPa. 6
The elastic modulus is calculated as the arithmetic mean of the measured values of three specimens. If, after measuring the elastic modulus, it is found that the difference between the prism compressive strength value f and the axial compressive strength value fm that determines the test control load exceeds 25% of the latter, the elastic modulus value is calculated as the arithmetic mean of the other two specimens. If two specimens exceed the above provisions, the test results are invalid.
Article 9.0.1 This test method is applicable to the frost resistance test of mortar with strength grade greater than M2.5 (2.5MPa) by freezing in negative temperature air and dissolving in positive temperature water.
Article 9.0.2 The preparation and maintenance of mortar frost resistance test pieces shall be carried out in accordance with the following requirements.
1. Mortar frost resistance test pieces adopt 70.7mm11×70.7mm×70.7mm cubic test pieces. In addition to the test pieces for identifying the mortar grade, two more groups (six pieces in each group) are prepared as frost resistance and comparative compressive strength test pieces of the same age as the frost resistance test pieces:
2. The preparation and maintenance methods of mortar test pieces are the same as those in Article 7.0.3 of this standard. Article 9.0.3 The test equipment shall meet the following requirements: 1. After the test piece is placed in the freezer (room), the temperature in the freezer (room) can be kept within the range of 15 to -20°C.
2. The basket frame is welded with steel bars, and its size corresponds to the size of the test piece. 3. The balance or table scale has a weight of 5kg and a sensitivity of 5g. 4. After the dissolved water is placed in the test piece, the water temperature can be kept within the range of 15 to 20°0.
5. The accuracy of the pressure testing machine (relative error of the indication) is not more than ±2%, and the range can make the expected breaking load value of the test piece not less than 20% of the full range and not more than 80% of the gold range.
Article 9.0.4 The antifreeze performance test of the slurry breaking shall meet the following requirements: 1. The test piece shall be subjected to the freezing test at the age of 28 days. Before the test, the freeze-thaw specimens and the comparison specimens should be taken out of the curing room, inspected and recorded for their original conditions, and then immersed in water at 15-20°C. The water surface should be at least 20mIH higher than the top surface of the specimens. The two groups of specimens should be taken out after two days of soaking and gently wiped off the surface moisture with a wrung wet towel, then numbered and weighed. The freeze-thaw specimens are placed in a basket for freeze-thaw tests, and the comparison specimens are placed in a standard curing room for curing; 2. During freezing or thawing, the basket must be 20mIII higher than the bottom of the container or the ground, and the distance between the specimens in the basket must be kept at least 50mm. 3. The temperature in the freezer (room) should be based on its central temperature. The freezing temperature of the specimens should be controlled at -15°C to -200°C. The specimens can only be placed when the temperature in the freezer (room) is lower than -15°C. If the temperature is higher than -15°0 after the specimen is placed, the freezing time of the specimen should be calculated when the temperature drops to 15°C again. The time from the installation of the specimen to the temperature dropping to -15°C again should not exceed 2 hours. Four, each freezing time is 4 hours. After freezing, it can be taken out and immediately placed in a water tank that can keep the water at 15-20 degrees to melt. At this time; the water level in the tank should be at least 20mm higher than the surface of the specimen, and the time for the specimen to melt in water should not be less than 4 hours. The freeze-thaw cycle ends when the melting is completed. Take out the specimen and send it to the freezer (room) for the next cycle test, and continue until the design specified number or the specimen is damaged.
5. After every five cycles, an appearance inspection should be carried out and the damage of the specimen should be recorded: when 4 of the 6 specimens in this group show obvious damage (delamination, cracking, through seams), the frost resistance test of this group of specimens should be terminated. 6. After the freeze-thaw test is completed, the freeze-thaw specimens and the comparison specimens should be dried at 105 ± 5\0 at the same time, and then weighed and pressure tested. If the surface damage of the freeze-thaw specimen is more serious, it should be repaired with cement slurry, and after leveling, it should be sent to the standard environment for curing for 2 days and then pressure tested at the same time as the comparison specimen.
Article 9.D.5 After the freeze-thaw test of the mortar, its strength coefficient and mass coefficient should be calculated according to the following formulas.
1. Strength loss rate of mortar specimens after freeze-thaw, 4fu-ffmx100
( 9.0.5-1)
Wherein, 4fm-Mortar strength loss rate after N freeze-thaw cycles (%), 1-mThe average value of compressive strength of the comparison specimens (MPa) m2The average compressive strength of 6 specimens after N freeze-thaw cycles is 194. The frost resistance test of the broken pulp shall be in accordance with the following requirements: 1. The specimens shall be subjected to the freeze test at the age of 28 days. Before the test, the thaw specimens and the comparison specimens shall be taken out of the curing room, and the appearance shall be inspected and their original conditions shall be recorded. Then, they shall be immersed in water at 15-20℃, and the water surface shall be at least 20mIH higher than the top surface of the specimens. The two groups of specimens shall be taken out after two days of immersion: and the surface moisture shall be gently wiped off with a wrung wet towel, and then numbered and weighed. The freeze-thaw specimens shall be placed in the basket for freeze-thaw test, and the comparison specimens shall be placed in the standard curing room for curing; 2. During freezing or thawing, the basket shall be 20mIII higher than the bottom of the container or the ground, and the distance between the specimens in the basket shall be at least 50mm; 3. The temperature in the freezer (room) shall be based on its central temperature. The freezing temperature of the specimens shall be controlled at -15℃ to -200℃. When the temperature in the freezer (room) is lower than -15°C, the specimen can be put in. If the temperature is higher than -15°C after the specimen is put in, the freezing time of the specimen should be calculated when the temperature drops to 15°C again. The time from the installation of the specimen to the temperature dropping to -15°C again should not exceed 2h. The freezing time for each time is 4h. After freezing, it can be taken out and immediately placed in a water tank that can keep the water temperature at 15-20°C for melting. At this time; the water level in the tank should be at least 20mm higher than the surface of the specimen, and the time for the specimen to melt in the water should not be less than 4h. The freezing and thawing cycle ends when the melting is completed. Take out the specimen and send it to the freezer (room) for the next cycle test, and continue until the design specified number or the specimen is damaged.
5. After every five cycles, an appearance inspection should be carried out and the damage of the specimen should be recorded: when 4 of the 6 specimens in this group show obvious damage (delamination, cracking, through seams), the frost resistance test of this group of specimens should be terminated. 6. After the freeze-thaw test is completed, the freeze-thaw specimens and the comparison specimens should be dried at 105 ± 5\0 at the same time, and then weighed and pressure tested. If the surface damage of the freeze-thaw specimen is more serious, it should be repaired with cement slurry, and after leveling, it should be sent to the standard environment for curing for 2 days and then pressure tested at the same time as the comparison specimen.
Article 9.D.5 After the freeze-thaw test of the mortar, its strength coefficient and mass coefficient should be calculated according to the following formulas.
1. Strength loss rate of mortar specimens after freeze-thaw, 4fu-ffmx100
( 9.0.5-1)
Wherein, 4fm-Mortar strength loss rate after N freeze-thaw cycles (%), 1-mThe average value of compressive strength of the comparison specimens (MPa) m2The average compressive strength of 6 specimens after N freeze-thaw cycles is 194. The frost resistance test of the broken pulp shall be in accordance with the following requirements: 1. The specimens shall be subjected to the freeze test at the age of 28 days. Before the test, the thaw specimens and the comparison specimens shall be taken out of the curing room, and the appearance shall be inspected and their original conditions shall be recorded. Then, they shall be immersed in water at 15-20℃, and the water surface shall be at least 20mIH higher than the top surface of the specimens. The two groups of specimens shall be taken out after two days of immersion: and the surface moisture shall be gently wiped off with a wrung wet towel, and then numbered and weighed. The freeze-thaw specimens shall be placed in the basket for freeze-thaw test, and the comparison specimens shall be placed in the standard curing room for curing; 2. During freezing or thawing, the basket shall be 20mIII higher than the bottom of the container or the ground, and the distance between the specimens in the basket shall be at least 50mm; 3. The temperature in the freezer (room) shall be based on its central temperature. The freezing temperature of the specimens shall be controlled at -15℃ to -200℃. When the temperature in the freezer (room) is lower than -15°C, the specimen can be put in. If the temperature is higher than -15°C after the specimen is put in, the freezing time of the specimen should be calculated when the temperature drops to 15°C again. The time from the installation of the specimen to the temperature dropping to -15°C again should not exceed 2h. The freezing time for each time is 4h. After freezing, it can be taken out and immediately placed in a water tank that can keep the water temperature at 15-20°C for melting. At this time; the water level in the tank should be at least 20mm higher than the surface of the specimen, and the time for the specimen to melt in the water should not be less than 4h. The freezing and thawing cycle ends when the melting is completed. Take out the specimen and send it to the freezer (room) for the next cycle test, and continue until the design specified number or the specimen is damaged.
5. After every five cycles, an appearance inspection should be carried out and the damage of the specimen should be recorded: when 4 of the 6 specimens in this group show obvious damage (delamination, cracking, through seams), the frost resistance test of this group of specimens should be terminated. 6. After the freeze-thaw test is completed, the freeze-thaw specimens and the comparison specimens should be dried at 105 ± 5\0 at the same time, and then weighed and pressure tested. If the surface damage of the freeze-thaw specimen is more serious, it should be repaired with cement slurry, and after leveling, it should be sent to the standard environment for curing for 2 days and then pressure tested at the same time as the comparison specimen.
Article 9.D.5 After the freeze-thaw test of the mortar, its strength coefficient and mass coefficient should be calculated according to the following formulas.
1. Strength loss rate of mortar specimens after freeze-thaw, 4fu-ffmx100
( 9.0.5-1)
Wherein, 4fm-Mortar strength loss rate after N freeze-thaw cycles (%), 1-mThe average value of compressive strength of the comparison specimens (MPa) m2The average compressive strength of 6 specimens after N freeze-thaw cycles is 19
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.