This standard specifies the test method for the flexural properties of glass fiber reinforced cement. This standard is applicable to the determination of the flexural properties of alkali-resistant glass fiber reinforced cement paste or mortar (GRC for short) GB/T 15231.3-1994 Test method for properties of glass fiber reinforced cement Flexural properties GB/T15231.3-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for the properties of glass fibre reinforced cementThe flexural properties
Subject content and scope of application
This standard specifies the test method for the flexural properties of glass fibre reinforced cement. GB/T 15231. 3-- 94
This standard is applicable to the determination of the flexural properties of alkali-resistant glass fiber reinforced cement paste or mortar (abbreviated as GRC). 2. Instrument
2.1 Electronic universal testing machine: range 50kN, accuracy 1%. 2.2 Vernier caliper: reading value 0.02mm.
3 Test piece
3.1 The test piece is 250mm long, 50mm wide and 10mm thick. If the thickness of the test piece is greater than 10mm and the width is 50mm, the length is 20 times the thickness plus 50mm. For the bending test for the purpose of inspecting the quality of products, if the test piece cannot be cut out from the product according to the specified size, the above 20 times can be changed to 16-20 times.
3.2 According to 3.1, cut the test piece from the middle of the test plate of 600mm×600mm×10mm, 6 pieces per group, 3.3 The test piece is fully moistened and cured for 26 days under the conditions of temperature 20±3℃ and relative humidity above 80%, and then placed in a well-ventilated room for 48 hours to make it in an air-dried state, and then the test is carried out. 3.4 The surface of the test piece is flat and the upper and lower surfaces are parallel, otherwise it needs to be ground before the test. 4 Test conditionswww.bzxz.net
The test is carried out indoors at 20±5℃.
5 Test steps
5.1 For a test piece with a thickness of 10mm, the span is 210mm. If the thickness of the test piece is greater than 10mm, the span is 20 times the thickness. In the bending test for the purpose of inspecting the quality of products, when the specimen cannot be cut from the product according to the specified size, the span of the specimen can be 16 to 20 times the thickness.
5.2 The support and loading method of the specimen is shown in Figure 1. The device is made of steel. Approved by the State Administration of Technical Supervision on September 24, 1994 and implemented on June 1, 1995
GB/T 15231.3-94
When applying the load, there are 3 specimens whose loads act directly on the front of the specimen, and the other 3 specimens whose loads act directly on the back of the specimen. 5.3 Load at a speed of 2 to 5 mm/min until failure, and draw the load-deflection curve by a function recorder. 5.4 Measure the width and thickness of each specimen. The method is as follows: measure the width of the failure zone (avoid the failure section) with an accuracy of 0.25 mm, measure the thickness along both ends of the width with an accuracy of 0.1 mm, and take the average value of the final thickness. If the failure occurs outside the middle small span, the specimen shall be discarded. 6 Calculation and evaluation of results
6.1 Obtain the following values ​​from the load-deflection curve: bending proportional limit load (i.e. the load at the point on the curve just starting to leave the straight line) W, maximum bending load. W2;
Two-thirds bending proportional limit load W:; Deflection of the loading point at W8.
6.2 Calculate the bending proportional limit strength according to formula (1): LOP
Bending proportional limit strength, MPa;
W,—bending proportional limit load, kN;
L—span, mm
specimen width, mm;
d—specimen thickness, mm.
6.3 Calculate the flexural strength according to formula (2):
Wherein: MOR
flexural strength, MPa,
maximum flexural load, kN;
span, mm,
specimen width, mm;
d-—specimen thickness, mm.
6.4 Calculate the flexural modulus according to formula (3): 418
. (1)
(2)
Wherein: E-flexural modulus, MPa;
GB/T 15231.3-94
2786ds×103
-two-thirds flexural proportional limit load, kN; L-span, mm;
W, deflection at the loading point, mm;
-specimen width, mm,
specimen thickness, mm.
If the deflection is measured at the center of the specimen span, the calculation formula should be: Eb
1088bd3
6.5 The results are expressed as the average value of 6 specimens, accurate to 0.1MPa. 7 Test report
The test report must include the following contents:
Type, size, age and curing conditions of the specimen; average value of the ultimate strength of flexural ratio (LOP); average value of flexural strength (MOR);
average value of flexural elastic modulus (E,);
Test date, unit and personnel.
Additional remarks:
This standard was proposed by the State Bureau of Building Materials Industry and drafted by the Building Materials and Concrete Research Institute of China Academy of Building Materials Science. The main drafter of this standard is Yang Ruishan.
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