Standard for autoclaved sand-lime brick

1. Subject content and scope of application This standard specifies the product classification, technical requirements, test methods, inspection rules, product certificate, stacking and transportation of autoclaved sand-lime bricks (hereinafter referred to as sand-lime bricks).
This standard is applicable to solid sand-lime bricks made from lime and sand as the main raw materials through blank preparation, compression molding and autoclave curing.
The lime and sand bricks specified in this standard shall not be used in the building parts that are subject to long-term heating of more than 200 ℃, rapid cooling and heat and acid medium erosion.
2. Reference standard GB2542 Inspection method for wall bricks (appearance quality, compression resistance, flexural strength, frost resistance)
GB5348 Terminology of bricks and blocks
3. Product classification
3.1 Product specification
3.1.1 Bricks are rectangular in shape. 3.1.2 The nominal size of brick is 240mm in length, 115mm in width and 53mm in height.
3.2 Product grade
3.2.1 According to the compressive strength and flexural strength, the strength grade is divided into 251), 201), 151) and 102).
3.2.2 According to the size deviation and appearance, it is divided into: a. superior products - A;
B. First class products - B;
C. Qualified products - C.
3.3 Product marking Lime sand brick product marking is printed in the order of strength grade, product grade and standard number, as shown below:
The strength grade is Grade 20, and the sand-lime brick of superior quality: LSB － 20 － A － GB l1945 Note:
1) Bricks above grade 15 can be used for foundation and other building parts.
2) Grade 10 bricks can be used for building parts above the moisture-proof layer.
4. Technical requirements
4.1 Dimensional deviation and appearance dimensional deviation and appearance shall comply with the provisions of Table 1.
4.2 Bending strength and compressive strength Bending strength and compressive strength shall comply with the provisions of Table 2. The frost resistance shall comply with the provisions of Table 3.
Table 1 The appearance quality of sand-lime brick mm project index excellent products first class qualified products
(1) Dimension deviation shall not exceed length ± 2 width ± 2 ± 3 height ± 1
(2) The corresponding height difference is not greater than 1 2 3
(3) The minimum damage size of missing edges and corners shall not be greater than 10 15 25
(4) The complete surface shall not be less than 2 strips and 1 top surface 1 strip and 1 strip and or 2 top surfaces and 1 top surface 1 top surface
(5) The crack length shall not be greater than a. the width direction on the large surface and the length extended to the strip surface; 30 50 70
B. Length direction on the large surface and its length extending to the top surface 50 70 100 or the length of horizontal cracks on the top surface
Table 2 Mechanical properties of sand-lime brick, MPa strength grade, compressive strength, flexural strength, average value, not less than single block value, not less than single block value, not less than 25 25.0 20.0 5.0 4.0 20 20.0 16.0 4.0 3.2 15 15.0 12.0 3.3 2.6 10 10.0 8.0 2.5 2.0 Note: the strength grade of superior products shall not be less than 15.
Table 3 Frost-resistance index, strength grade, compressive strength, MPa, dry mass loss of single brick,% average value shall not be less than 25 20.0 2.0 20 16.0 2.0 15 12.0 2.0 10 8.0 2.0 Note: the strength grade of superior products shall not be less than 15 grade.
5. Inspection method
5.1 Dimensional deviation and appearance inspection shall be conducted according to GB2542.
5.2 Bending strength test
5.2.1 Instrument, equipment and material testing machine: the relative error of indication value shall not exceed ± 1%, and the selection of measuring range shall make the maximum failure load of the sample fall within 20~80% of the full load.
5.2.2 Sample
5.2.2.1 Number and requirements of samples: 5 brick samples shall be taken, and the surface of the test piece shall be flat.
5.2.2.2 Sample treatment Place the brick sample in water with temperature above 15 ℃ for 24h, and then take it out. Wipe off the surface moisture with a wet cloth.
5.2.3 Test steps
5.2.3.1 Measure the width at the middle of the two large faces of the brick sample and the height at the middle of the two faces. Take the average values B and H respectively, accurate to 1mm.
5.2.3.2 Place the brick sample flat on the support of the material testing machine, and the span L is 200mm. When the brick sample has cracks or dents, the large face with cracks or dents shall be downward. At the center of the span, apply the load uniformly at the loading speed of 0. l - 0.2 kN per second until the brick sample is damaged, and record the failure load P.
5.2.4 Result calculation and evaluation
5.2.4.1 The bending strength Rc is calculated according to formula (1) (accurate to 0.1MPa): 3PL Rc ＝ -- (1) 2BH [2], where: P -- failure load 0; L - span is 200mm; B - brick sample width, mm; H - brick sample height, mm.
5.2.4.2 The evaluation of results shall be determined according to the arithmetic mean of the test values of five brick samples and the minimum single block value, accurate to 0.1MPa.
5.3 Compressive strength test
5.3.1 Instrument, equipment and material testing machine: the relative error of indication value shall not be greater than ± 1%, and the selection of range shall make the maximum failure load fall between 20% and 80% of full load.
5.3.2 Specimen Take the brick sample after the bending strength test for compression test. Place the two half-cut bricks on the opposite side, and the overlapping part shall not be less than 100mm (as shown in Figure 1). If it is less than 100mm, take another spare brick sample to make up 5 pieces, and calculate the bending strength again.
5.3.3 Test step: place the brick flat in the center of the pressing plate of the material testing machine, and apply the load at the speed of 2.5-5.0 kN per second until the brick sample is damaged.
5.3.4 Calculation and evaluation of results
5.3.4.1 Calculation of results, the compressive strength Pp is calculated according to formula (2) (accurate to 0.1MPa): P Pp ＝ - (2) LB, where: P - failure load N; L -- length of the overlapped part of the brick sample, mm; B -- brick sample width, mm.
5.3.4.2 The results shall be evaluated according to the arithmetic mean of the test values of five brick samples and the minimum single block value, accurate to 0.1MPa.
5.4 Anti-freezing test
5.4.1 Low-temperature refrigerator or freezing room of instruments and equipment: after placing brick samples, the temperature in the box (room) can reach or be lower than - 20 ℃.
5.4.2 Take 5 brick samples and clean the surface of the brick samples.
5.4.3 Test steps
5.4.3.1 Put the sample in the oven and bake it to constant weight at 105 - 110 ℃ (the interval is 4h, and the mass difference between the two times is not more than 0.5%, which is constant weight), and then weigh its mass after cooling to room temperature.
5.4.3.2 Immerse the sample in 10-20 ℃ water, take it out after 48h, wipe off the surface moisture with a wet cloth, and place it in a freezer that has been pre-cooled to below 15 ℃ at a spacing of more than 20mm.
5.4.3.3 When the temperature in the box is cooled to - 15 ℃ again, start to count, freeze at - 15~- 18 ℃ for 5h, take it out and put it into 15-20 ℃ water to melt for 3h, and repeat the freeze-thaw cycle for 15 times as an anti-freeze test.
5.4.3.4 Check the damage of the sample during the freeze-thaw process every 5 freeze-thaw cycles.
5.4.3.5 After 15 freeze-thaw cycles, put the sample in an oven at 105~110 ℃ to dry to constant weight, and weigh its mass after cooling to room temperature.
5.4.3.6 Immerse the brick sample in 10-20 ℃ water, take it out after 24h, divide the brick sample into two sections with appropriate methods, and conduct the compressive strength test according to the provisions of Article 5.3.
5.4.4 Calculation and evaluation of results
5.4.4.1 The mass loss rate is calculated according to formula (3): G0 － G Gm ＝ -- × 100........................................................... (3) G0 formula: Gm -- mass loss rate,%; G0 - drying mass of sample before test, g; G -- drying mass of sample after test, g.
5.4.4.2 The evaluation of the results is determined by the arithmetic mean of the compressive strength of five samples and the mass loss rate (%) of a single brick.
6. Inspection rules
6.1 Delivery inspection
6.1.1 Inspection items The ex-factory inspection items include: dimensional deviation, appearance, flexural strength and compressive strength.
6.1.2 One batch of every 100000 bricks, and one batch of less than 100000 bricks, but not less than 20000.
6.1.3 Sampling
6.1.3.1 Use mechanical random sampling method to select 100 bricks for dimensional deviation and appearance inspection. 6.1.3.2 Take 3 groups of 15 brick samples (5 for each group) from the brick samples with size deviation and acceptable appearance according to the random sampling method. Two groups were tested for compressive strength and flexural strength, and one group was standby.
6.1.4 Determination.
6.1.4.1 If there are no more than 10 bricks with poor size and appearance that do not meet the requirements of superior products in Table 1, the batch of bricks with poor size and appearance will be judged as superior products; If the number of bricks that do not meet the requirements of first class products does not exceed 10, the batch of bricks will be judged as first class products; If the number of bricks that do not meet the requirements of qualified products does not exceed 10, the batch of bricks will be judged as qualified products. If the number of bricks that do not meet the requirements of qualified products exceeds 10, the products with dimension deviation and appearance disqualification in this batch of bricks can be selected to form a new batch for re-sampling inspection. 6.1.4.2 The flexural strength and compressive strength of this batch of bricks are determined by the average and minimum values of two groups of tests according to Table 2.
6.1.4.3 The grade of each batch of bricks shall be determined according to Table 1, Table 2 and Table 3.
6.1.5 Re-inspection
6.1.5.1 If the purchasing and lending unit has any objection to the inspection results of the ex-factory products, it can take samples together with the manufacturer according to the sampling method specified in this standard, and entrust the product quality supervision and inspection institution to conduct re-inspection. Re-inspection items include flexural strength, compressive strength, frost resistance, dimensional deviation, appearance or some of them.
6.1.5.2 Dimension deviation and appearance re-inspection of bricks shall be conducted in the production plant.
6.2 Type inspection
6.2.1 The type inspection shall be carried out if the inspection conditions are one of the following conditions: a. the type identification of the trial production in the new factory; B. After the formal production, the raw materials and processes have changed greatly, which may affect the product performance; C. During normal production, inspection shall be conducted once a year; D. When the production of the product is suspended for more than 3 months and the production is resumed; E. The factory inspection result is significantly different from the last type inspection; F. When the national quality supervision institution puts forward the requirements for type inspection.
6.2.2 Inspection items. The inspection items include: dimensional deviation, appearance quality, bending strength, compressive strength and frost resistance.
6.2.3 The batch and sampling shall be carried out according to 6.1.2, and four groups of 20 brick samples shall be taken. Among them, 2 groups were tested for compressive strength and flexural strength, 1 group was tested for frost resistance, and 1 group was for standby.
6.2.4 The judgment shall be conducted according to 6.1.4. If the frost resistance meets the corresponding strength grade in Table 3, it shall be judged as meeting the grade.
7. Product certificate, stacking and transportation
7.1 Ex-factory products shall have product certificate, which includes: a. name of manufacturer; B. Trademarks; C. Product marking; D. Actual technical performance and production date of this batch of products.
7.2 The lime sand bricks shall be stored for 3 days before leaving the factory. The products shall be stored and stacked in such a way that the site is flat, graded, neat and stable.
7.3 During the transportation and loading and unloading of products, it is strictly prohibited to drop, throw and dump.
Additional notes:
This standard is proposed by the National Bureau of Building Materials Industry.
This standard is drafted by the Silicate Building Products Quality Supervision and Inspection Center of the State Building Materials Bureau.
The main drafters of this standard are Jiang Bingnian, Bao Junhai, Gu Guangyan, Li Jianzhong and Yang Guanghui.
The Standard is interpreted by the Silicate Building Products Quality Supervision and Inspection Center of the State Building Materials Bureau.
From the date of implementation of this standard, the original Ministry of Building Materials Industry standard JCl53-75 "Autoclaved Lime Sand Bricks" is invalid.