MT/T 780-1998 English PDFUS$399.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. MT/T 780-1998: Accelerating agent of shotcrete used in coal mines Status: Obsolete
Basic dataStandard ID: MT/T 780-1998 (MT/T780-1998)Description (Translated English): Accelerating agent of shotcrete used in coal mines Sector / Industry: Coal Industry Standard (Recommended) Classification of Chinese Standard: Q12 Classification of International Standard: 91.100.10; 73.100.30 Word Count Estimation: 10,192 Date of Issue: 11/10/1998 Date of Implementation: 4/1/1999 MT/T 7:---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.Accelerating agent of shotcrete used in coal mines ICS 91.100.10; 73.100.30 Q12 People's Republic of China Coal Industry Standard Accelerator for sprayed concrete in coal mine Accelerating agent of shotcrete used in coal mines 1998-11-10 released.1999-04-01 implemented Published by the National Coal Industry Bureau ContentsForeword Ⅱ 1 Scope 1 2 Normative references 1 3 Definition 1 4 Technical requirements 1 5 Test method 2 6 Inspection rules 6 7 Packaging and storage 7ForewordBolt and shotcrete support is one of the main support methods for underground mining in China. Accelerating agent is an essential addition to ensure the effect of bolt and shot Agent, the formulation of this standard has a positive effect on ensuring the improvement of the quality of quick setting products. With the development of science and technology, this standard added two parameters, alkalinity and shrinkage ratio, when it was formulated. JC was referenced in the development of this standard 477-1992 `` Quick-setting agent for sprayed concrete '' and absorbed production, scientific research, and use units experience of. This standard is proposed by the Industry Management Department of the State Coal Industry Bureau. This standard is under the jurisdiction of the Coal Industry Coal Mine Professional Equipment Standardization Technical Committee. Drafting organizations of this standard. Beijing Institute of Well Research, China Coal Research Institute, Jiaozuo Mining Bureau Cement Plant Accelerator Branch, Jiangxi Pingxiang Mine Bureau Qingshan Building Material Factory, Shandong Xiangye Daily Chemical Co., Ltd. Accelerator Factory. The main drafters of this standard. Wang Huiyun, Guo Jianming, Xi Kongsheng, Li Jinghua, Ye Zhenbo, Jin Yuesheng, Huang Aiyue. This standard is entrusted to the Beijing Institute of Construction of Coal Science Research Institute for interpretation. People's Republic of China Coal Industry Standard Accelerator for sprayed concrete in coal mine Accelerating agent of shotcrete used in coal mines MT/T 780-1998 Approved by the State Coal Industry Bureau in.1998-11-10 and implemented in.1999-04-011 ScopeThis standard specifies the definition, technical requirements, and determination of sprayed concrete accelerators (hereinafter referred to as accelerators) for underground and surface engineering of coal mines. Methods, inspection rules, sampling, packaging and storage. This standard applies to inorganic salt powder quick-setting agents for underground and ground sprayed concrete in coal mines.2 Reference standardsThe following standards contain provisions that, through reference in this standard, constitute provisions of this standard. When this standard was published, the editions shown were all Is effective. All standards will be revised, and all parties using this standard should explore the possibility of using the latest versions of the following standards. GB 177-1985 Test method for strength of cement mortar GB 178-1987 standard sand for cement strength test GB 1345-1991 cement fineness test method (80 μm sieve analysis method) GB 1346-1989 Test method for water consumption, setting time and safety of standard cement consistency GB 3350.4-1982 Compression fixture for cement physical inspection instrument GB 8076-1987 concrete admixture JC 313-1982 Expansion cement expansion method3 DefinitionThis standard uses the following methods. 3.1 Accelerating agent An admixture that enables concrete (or mortar) to rapidly set and harden. 3.2 Reference cement mortar nomal cement mortar In accordance with the test conditions specified in this standard, the standard curing cement mortar is formulated with reference cement and standard sand without any accelerator. 3.3 tested cement mortar tested cement mortar According to the test conditions specified in this standard, the standard curing cement mortar mixed with the accelerator and the standard cement formulated with the standard cement and standard sand is used. 3.4 Ratio of compressive strength of compressive strength The ratio of the compressive strength of the tested cement mortar to the benchmark compressive strength of a certain curing age in accordance with this standard. 3.5 Shrinkage ratio of shrinkage rate The ratio of the shrinkage rate of the tested cement mortar to the shrinkage rate of the benchmark cement mortar in a curing age period in accordance with this standard.4 Technical requirements4.1 The parameters and performance indicators of the accelerator, the mixture with the accelerator and the hardened mortar shall be as specified in Table 1. Table 1 Parameter performance index Setting time (min) Initial setting Final setting Compressive strength ratio (%) d ≥105 d ≥70 Fineness μm sieve residue (%) ≤14 Water content (%) ≤2 Alkalinity (for ground) pH≤13 d shrinkage ratio (%) ≤1405 Test method5.1 The test raw materials shall meet the following requirements 5.1.1 Reference cement. Benchmark cement should meet GB 8076 regulations. When the benchmark cement cannot be obtained for any reason, C3A content of 6% ~ 8%, alkali content is allowed. The amount (Na2O 0.658K2O) of not more than 1% of clinker and dihydrate gypsum and slag milled is greater than (inclusive) 5.1.2 Standard sand. Standard sand should meet GB Relevant provisions of 178. 5.1.3 Water. Drinking water should be used. 5.2 Determination of setting time 5.2.1 Instruments and equipment. Instruments and equipment should comply with GB Relevant provisions of 1346. 5.2.2 Environmental conditions shall meet the following requirements. a) Ambient temperature. the temperature of the test room, the temperature of various raw materials, the bottom mold of the coagulation time tester and the temperature of the test mold should be maintained at 20 ± 2 ℃; b) Environmental relative humidity. 50% ~ 70%. 5.2.3 Determination steps. a) Standard test of the setting time tester and apply mold release agent or oil to the circular test mold and the glass bottom plate b) Wipe the mixing pot with a damp cloth and weigh the reference cement 400 g into a mixing pot; c) Weigh the accelerator 16 g or as recommended by the manufacturer but not more than 16 g accelerators are placed in the benchmark cement; d) Use a mixing shovel to dry mix the reference cement and the accelerator quickly, and pile them into a concave ring with a raised ring on the periphery; e) Measuring cylinder 160 mL of water, and gently pour the water into the dry material of cement and accelerator, start timing, use a mixing spatula at 25 s clock Mix well inside; f) Put the mixed cement paste into the test mold of the setting time tester, shake it several times on the platform, and ensure that the slurry fills the bottom of the test mold. The scraper scrapes off the excess slurry and smoothes it, and places it on the base of the setting time tester; g) Touch the tip of the test needle to the surface of the test piece, tighten the screws, and then suddenly loosen, and observe the depth of the mold when the pointer of the tester is set. by Timing when adding water, the test needle is 0.5 ~ 1 from the bottom of the glass plate The time required for mm is the initial setting time, and the test needle sinks into the slurry no more than 1.0 mm required The time is the final setting time. Before the initial setting of the cement paste, after the screws are loosened, hold the test rod with your hand to prevent the test needle from colliding. 5.2.4 Evaluation of results. The above test shall be performed twice, and the arithmetic mean of the two tests shall be taken as its result; if the difference between the two tests is greater than s. This test is invalid. The test should be repeated. 5.3 Determination of compressive strength ratio 5.3.1 Instruments and equipment. Instruments and equipment for compressive strength measurement shall comply with GB Relevant provisions of 177. 5.3.2 Environmental conditions shall meet the following requirements. a) Ambient temperature. The temperature of the test room, various raw materials and the temperature of the test mold should be maintained at 20 ± 2 ℃; b) Environmental relative humidity. 50% ~ 70%; c) Test piece curing temperature. 20 ± 2 ℃; d) Relative humidity for test specimen maintenance. not less than 90%. 5.3.3 Determination steps. a) Weigh reference cement 750 g, standard sand 1125 g, put into a mixing pot wiped with a damp cloth and mix well dry, pile in the middle concave, convex around Ring b) 375 Pour mL of water into the dry material of the mixing pot, stir quickly and load it into the triple test mold; c) Put the triple test mold on the rubber sand shaker and shake for 30 s, and smooth it with a spatula; d) Add accelerator 30 in step 5.2.3.a g or less than 30 as recommended by the manufacturer g accelerator, repeat the above steps; e) Accelerating and non-accelerating coagulant test pieces are formed into 2 groups, and placed in a curing box for curing together with the test mold; f) 24 h After demolding, one comparison group immediately performed the compressive strength test, and the other comparison group was placed in a curing box for curing. anti-stress strength; g) The allowable deviation of the measurement time of each age is shown in Table 2; Table 2 Test age (d) Time tolerance (h) 1 ± 0.5 28 ± 10 h) The compressive strength of each age must be measured with a compressive fixture. The compressive fixture should comply with GB 3350.4 requirements, test specimen compression area For 40 mm × 62.5 mm, the dirt on the pressure surface and the pressure plate surface of the test piece should be removed before the measurement, the side of the test is the pressure surface, and the side of the test piece Should be close to the fixture positioning pin; i) Loading speed should be controlled at 5 ± 0.5 kN/s. 5.3.4 Calculation and Evaluation of Results 5.3.4.1 The compressive strength is calculated according to formulas (1) and (2) RA = PA SA (1) RB = PB SB (2) Where. RA --- compressive strength of benchmark cement mortar, MPa; RB --- compressive strength of tested cement mortar, MPa; PA --- Basic cement mortar test block failure load, N; PB --- the failure load of the tested cement mortar block, N; SA --- compressed area of benchmark cement mortar test block, SA = 40 mm × 62.5 mm; SB --- Compressed area of tested cement mortar test block, SB = 40 mm × 62.5 mm. 5.3.4.2 Evaluation of results. Remove the two largest and smallest values of the six compressive strength values of each group, and take the arithmetic mean of the remaining four measurements Mean. 5.3.4.3 The compressive strength ratio is calculated according to formula (3). N = RB RA × 100% (3) Where. N --- compressive strength ratio,%; RA --- compressive strength of benchmark cement mortar, MPa; RB --- The compressive strength of the tested cement mortar, MPa. 5.4 Determination of moisture content 5.4.1 Instruments and equipment. a) Balance. Weigh.200 g, sensitivity 0.1 g; b) Electric heating blast drying oven. temperature control 0 ~.200 ℃; c) Weighing bottle with lid. 65 diameter mm, height 25 mm; d) Drying box. It contains color-changing silica gel. 5.4.2 Determination steps. a) Put the cleaned weighing bottle with the lid together in the oven, and place it in 105 ~ 110 Bake at 30 ℃ min. Remove and place in desiccator Intercooling 30 Min weighs its mass, repeats the above steps until constant weight, and its mass is m0; b) Weigh the sample of the quick setting agent that maintains the original water content 10.0 ± 0.1 g, into a weighing bottle with a constant weight, cover the lid and weigh out the sample And the total weight of the weighing bottle m1; c) Open the cap of the weighing bottle and place the weighing bottle containing the accelerator sample into 105 ~ 110 ℃ in oven 2 h, remove the cover and put Cool in a desiccator 30 Weigh in min and repeat the above steps until the weight is constant m2. 5.4.3 Calculation and Evaluation of Results 5.4.3.1 The water content is calculated according to formula (4). M = m1-m2 m1-m0 × 100 (4) Where. M --- water content,%; m0 --- weighing bottle weight, g; m1 --- weigh the bottle before drying the sample weight, g; m2 --- Weigh the bottle and dry the sample weight, g. 5.4.3.2 Evaluation of results. The moisture content shall be determined three times, and the arithmetic mean of the three determination results shall be accurate to 0.1%. 5.5 Fineness measurement Accelerator fineness according to GB The negative pressure sieve method in 1345 was performed.When the negative pressure sieve method was used unconditionally, manual dry sieve method was allowed. Law should be in accordance with GB 1345 Appendix A. But arbitration and type inspection must use the negative pressure sieve method. 5.6 Alkalinity determination 5.6.1 Instruments and equipment. a) Acidity meter. resolution 0.01 pH; b) composite electrode; c) Pallet balance. weighing 100 g, sensitivity 0.1 g; d) Wide mouth bottle. volume 300 mL; e) graduated cylinder. volume.200 mL; f) Beaker. Volume 50 mL; g) Quick qualitative filter paper. 5.6.2 Determination steps. a) Adjust the acidity meter and composite electrode according to the instruction manual; b) Weigh the quick setting agent 10 with a tray balance g; c) Measure the clean water with a measuring cylinder 100 mL; d) Rinse the jar with clean water; e) Will weigh well 10 g quick-setting agent into a wide-mouth bottle, and quickly add 100 The mL of clean water is also poured into a wide-mouth bottle. Akira 1 h; f) Slowly filter the above mixture with a qualitative filter paper to a volume of 50 The height of the filtrate in the mL beaker should be higher than that of the composite electrode Sand core micropore 5 mm; g) Adjust the acidity meter again; h) Rinse the composite electrode with clean water, immerse it in the test solution, observe the acidity meter, and when it is stable, record the Indication, which is the pH value of the tested coagulant; i) Remove the composite electrode from the filtrate and rinse it with clean water for later use; j) When measuring with an acidity meter unconditionally, precision colorimetric test paper is allowed, but the acidity meter method must be used for arbitration and type inspection get on. 5.6.3 Evaluation of results. The measurement shall be performed three times, and the arithmetic mean of the three determination results shall be taken to the nearest 0.1 pH. 5.7 Shrinkage ratio measurement 5.7.1 Instruments and equipment. Various instruments such as test molds, nail heads, and length gauges for measuring shrinkage ratio should comply with JC Relevant provisions of 313. 5.7.2 Environmental conditions. a) Ambient temperature. 20 ± 2 ℃; b) Relative ambient temperature. 50% ~ 60%. 5.7.3 Determination steps. a) Weigh reference cement.200 g, standard sand 400 g. Pour into a mixing pot wiped with a damp cloth and mix well; b) Coat the test mold with motor oil, and then apply oil to both ends of the nail head into the side holes of the test mold; c) Measure 96 Pour mL of water into the dry material of the mixing pot and mix quickly; d) Pour the mixed wet material into the test mold, pay attention to the paste to fill the copper nails at both ends of the test mold, and place it on the vibration table for 30 seconds. s, using a spatula Scrape off excess slurry and smooth it; e) Weigh 8 g or less than 8 as recommended by the manufacturer g, but must meet the requirements of this standard setting time and compressive strength ratio indicators Repeat the above steps to make a test piece of accelerated coagulant; f) 24 ± 2 h demould, place the test piece on the length meter to determine the initial reading; when measuring, rotate the test piece left and right several times, take the middle flat average; g) The test specimen age is 1 d, 3 d, 7 d, 14 d, 28 d, 60 d, 90 d. 5.7.4 Calculation and evaluation of results. 5.7.4.1 The shrinkage rate is calculated according to formulas (5) and (6). St1 = Lt-L0 L × 100 (5) St2 = Lt-L0 L × 100 (6) Where. St1 --- Tested cement mortar shrinkage,%; St2 --- Basic cement mortar shrinkage,%; Lt --- measurement reading of a certain age, mm; L0 --- initial measurement reading, mm; L --- effective length of test piece, L = 250 mm. 5.7.4.2 The shrinkage ratio is calculated according to formula (7). St = St1 St2 × 100 (7) Where. St --- shrinkage ratio,%; St1 --- Tested cement mortar shrinkage,%; St2 --- Basic cement mortar shrinkage,%. 5.7.4.3 Evaluation of results. The measurement shall be performed three times, and the arithmetic mean of the three measurement results shall be taken; if the difference between the maximum and minimum values and the average value 10% difference, this test is invalid, the test should be repeated.6 Inspection rules6.1 Inspection classification 6.1.1 Inspection is divided into factory inspection and type inspection, and the items to be inspected are carried out according to Table 3. Factory inspection is carried out by the quality inspection department of the manufacturer. The type inspection is carried out by the product quality supervision and inspection center or the unit designated by the competent authority. 6.1.2 Accelerators must pass the inspection and be accompanied by a certificate before leaving the factory. table 3 Test items category Setting time compressive strength fineness moisture content alkalinity shrinkage Underground use Factory inspection √ √ √ Type inspection √ √ √ √ Inoue use Factory inspection √ √ √ √ √ √ Type inspection √ √ √ √ √ √ 6.2 Type inspection shall be carried out in any of the following cases. a) Trial-type identification of new products or old products transferred to the factory; b) When production resumes six months after the suspension; c) when raw materials and production processes are changed; d) regular production inspection every six months; e) When there is a large difference between the factory inspection result and the last type inspection result (relative error is greater than 5%); f) When requested by the national quality inspection agency. 6.3 Batch Accelerators are numbered during production, and each number is a batch, which is a sampling unit. 6.3.1 Annual output 6000 Above t, every.200 t is a number. 6.3.2 Annual output 4000 ~ 6000 t, every 150 t is a number. 6.3.3 Annual output.2000 ~ 4000 t, every 100 t is a number. 6.3.4 Annual production is less than.2000 t, every 5 d Yield is a number. 6.4 Sampling and sample retention 6.4.1 The sampling should be representative, and can be taken continuously, or an equal amount of samples can be taken from more than 20 different parts, with a total of not less than 1. kg. 6.4.2 Retaining samples. The samples taken for each number should be thoroughly mixed and divided into two equal parts. One for inspection; one sealed for three months to When there is a problem, it shall be submitted to the inspection agency designated by the state for re-inspection or arbitration. 6.5 Decision rules If the setting time, compressive strength ratio, and fineness are all qualified, it will be judged as a qualified product. If it fails, the batch is judged as a failed product. Alkalinity, shrinkage, and water content are used as reference indicators. ...... |
