Physical property test of pyrotechnic aggregate

2022-08-07
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Physical property test of stone

physical property test of stone - density test (true density)

the density of stone is also called true density, which is the mass (g/cm3) of stone per unit real volume (excluding pore volume) under the specified conditions (105 ℃± 5 ℃ drying to constant weight, temperature 20 ℃). It is one of the physical constants of stone and one of the parameters for calculating the porosity of stone. The density depends on the types of rock forming minerals and the organizational structure of rocks. The higher the density of stone, the better the engineering performance. The density of stone for general engineering is 2.5 ~ 3.1g/cm3. The density of stone is measured by (1) Li's density bottle and (2) (pyknometer method). Li's bottle method is to replace the solid volume of stone powder of known quality with kerosene according to the "replacement" principle

I. test purpose:

this test is to determine the mass of mineral unit volume (excluding open and closed pores) of stones containing water-soluble mineral components when they are dried to constant weight at the specified temperature, and to provide a basis for calculating the porosity of stones

II. Main instruments, equipment and appliances:

(1) Li's bottle: the volume is 220~250ml, with a thin neck about 18~20 cm long and about 1 cm in diameter. There are scale readings on the thin neck, accurate to 0.1ml. (2) Rolling mill; (3) . oven; (4) Balance (weighing 500g, sensitivity 0.01g); (5) Ball mill, (6) measuring cylinder, (7) mortar, (8) funnel, (9) thermometer, (10) spoon, (11) extractor, (12) mineral oil (kerosene): there is no water, so it is necessary to filter and remove the air in kerosene (or manual exhaust) before use. Porcelain dish, filter paper, dryer, 0.25mm sieve, etc. (13) Thermostatic water tank: when measuring density, it is necessary to get two readings at the same temperature. Therefore, it is necessary to prepare a thermostatic water tank or other water glass containers that maintain a constant temperature. The thermostatic containers should be able to maintain the scale line of (t ℃± 1 ℃) t=20

III. sample preparation: primary crushing, passing 0.25mm sieve

take the representative rock sample and grind it on a small stone mill (or manually), then put it into a ball mill for further grinding, and then grind it with a mortar to make it all crushed into stone powder that can pass the 0.25 ㎜ sieve

IV. test steps:

(1) weigh 100g, bake to constant weight, and cool to room temperature for standby

use a porcelain dish to weigh 100g of stone powder, put it in an oven at 105 ℃±℃ and bake it to constant weight. The drying time is generally 6~12h, and then put it in a dryer to cool it to room temperature for standby

(2) pour kerosene into the bottle above the zero mark, place it in t ℃ thermostatic water for 0.5h, and record the first reading V1, accurate to 0.05ml

pour the kerosene extracted from the air into the Li's pyknometer above the zero scale mark, and take the initial reading (subject to the lower part of the meniscus); Then place the Li's pyknometer in a t ℃ thermostatic water bath, immerse the scale part in water (the water temperature must be controlled at the temperature when the Li's pyknometer is calibrated), keep the temperature constant for 0.5h, and record the first reading V1, accurate to 0.05ml

(3) carefully wipe the bottle

take out the Li's pycnometer from the constant temperature water bath, and carefully wipe the part without kerosene above the starting reading of zero point in the Li's pycnometer with filter paper

(4) accurately weigh the mass (M1) (accurate to 0.001g)

accurately weigh the combined mass (M1) (accurate to 0.001g) of the cooled porcelain dish and stone powder, carefully put the stone powder into the bottle through the funnel with a bull bone spoon, so that the liquid level is up to the 20ml scale (or slightly higher than the 20ml scale), and do not make the stone powder adhere to the inner wall of the bottleneck above the liquid during pouring. Shake the lees pycnometer to exhaust the air or use an air extractor to exhaust the air until no bubbles appear in the liquid. Then put it into the thermostatic water bath and keep it constant for 0.5h at the same temperature (the same temperature as the first reading) to record the second reading. V2 accurately weigh the combined mass m2 of porcelain dish and residual stone powder

v. result arrangement: (1) calculate the density of the stone, accurate to 0.01g/cm:

where: ρ—— Stone density, g/cm

m1______ Combined mass of stone powder and porcelain dish before test, G

m2 -- combined mass of residual stone powder and porcelain dish after test, G

v - volume of liquid discharged by stone powder, that is, the second reading (V2) - the first reading (V1) cm

(2) take the arithmetic mean value of the two test results as the measured value. If the difference between the two test results is greater than 0.02g/cm, re sample for test

[precautions]

(1) this method is suitable for measuring the density of any powdery materials such as cement, lime and pulverized coal, which are processed and analyzed by microcomputer

(2) iron filings shall be absorbed by magnet: the stone shall be ground into stone powder in the density test. The iron filings in the stone powder must be absorbed by magnet before drying, but the mineral powder used for asphalt mixture is not necessary

(3) slow loading: during the process of adding stone powder to the density bottle, the flying and scattering of stone powder should be minimized. At the same time, the adding speed should not be fast. Add a spoonful until it falls to the bottom of the bottle, and then add another spoonful, otherwise it will be blocked

(4) cleaning; After adding the stone powder, clean the stone powder on the funnel and the mouth of the density bottle into the density bottle with a brush and other appropriate tools

(5) analyze the reasons for sticking to the wall: if the stone powder sticks to the inner wall of the density bottle during the test, it means that the stone powder is not dry, or the kerosene contains water, or the density bottle is not clean, find out the reasons and retest

(6) clean and store: after the test, the density bottle shall be cleaned and stored with kerosene. It is not necessary to clean it with water. If it is cleaned with water, it must be dried before the test

physical property test of stone - Gross bulk density test (hydrostatic weighing method)

under the specified conditions (drying to constant weight at 105 ℃± 5 ℃, weighing the mass in the air, and weighing the mass in the water after saturated with water), the mass per unit gross volume (volume of mineral bearing entity, open and closed pore volume, i.e. the volume surrounded by the outer contour of the test piece) of stone is called gross bulk density (g/cm). The gross bulk density is one of the physical constants of stone and one of the parameters for calculating the porosity of stone. The larger the gross bulk density, the smaller the porosity of the stone, and the better the engineering performance. The gross bulk density was measured by weighing in water. Wax sealing method shall be adopted for stone materials that disintegrate, dissolve, expand or are relatively soft in water

I. purpose and scope of application: determine the mass of solid material per unit volume of stone. This method is not suitable for hydration reaction

(1) determine the mass of solid material per unit volume including pores of stone in dry state

(2) it is not suitable to use static water weighing method to measure the density of soft stone that disintegrates in water, is soluble and has dry shrinkage and wet expansion

II. Instruments and equipment: specimen processing equipment: stone cutter, diamond machine, grinding machine and small hammer, etc

industrial balance: weighing 500g, sensitivity 0.01g

oven: it can control the temperature within 105 ± 5 ℃

hydrostatic balance: balance disc, hook, crane, water dissolver, etc

III. sample: preparation number

the stone sample shall be hammered into an irregular shape specimen with a particle size of about 50mm for at least 3 times, or the stone sample shall be made into 3 cube specimens with a side length of 50mm (or cylinder specimens with a diameter and height of 50mm), washed clean, and marked with the number for standby

IV. test steps:

(1) bake to constant weight and cool to room temperature

put the test piece into the oven and bake it at 105 ± 5 ℃ to constant weight. The drying time is generally 12~24h. Take out the test piece and place it in the dryer to cool it to room temperature

(2) weigh m, accurate to 0.01g

take the test piece out of the drying range and put it on the balance to weigh m, accurate to 0.01g (the weighing accuracy of this test is the same)

(3) immerse the test piece in water for 48h

place the weighed test piece in a water container, inject water to 1/4 of the height of the test piece first, then inject water to 1/2 and 3/4 of the height of the test piece every 2h, and add water to more than 20mm above the top surface of the test piece after 6h. Since the production capacity has not increased synchronously with the vigorous market demand, it is convenient for the air in the test piece to escape. After all the test pieces are submerged by water, they can absorb water freely for 48h

(4) take out the soaked test piece, wipe the surface moisture of the test piece with a wet cloth, and immediately weigh its mass M1

(5) weigh the mass m2 in the water of the test piece after the water absorption is saturated

v. result arrangement: the gross bulk density of stone is calculated according to the following formula, accurate to 0.01g/cm

where: ρ H - Gross bulk density of stone, g/cm

m - mass of test piece when drying to constant weight, G

v - stone volume, cm

m1 - mass of surface dry water saturated specimen in air, G

m2 - mass of surface dry water saturated specimen in water, G

-- density of water, taken as 1g/cm3 during calculation

for rocks with uniform texture, the density shall be the average value of the results measured by three specimens; The maximum and minimum density of rocks with uneven organization shall be recorded

calculation: the surface dry saturated water density and apparent density (apparent density) of the stone can be calculated according to the following formula:

(1) (2)

apparent density (apparent density):

the symbol meaning is the same as above

[precautions]

(1) the sample must be dried to constant weight. Generally, the drying time shall not be less than 12h

(2) it is suitable to use regular samples: regular samples or irregular samples can be used as samples. However, according to the comparative test results, the density of regular samples is slightly higher than that of irregular samples. Therefore, although it is specified that irregular samples can be used, regular samples are preferred

physical property test of stone - Gross bulk density test (wax sealing method)

I. purpose and scope of application:

determine the mass of solid material per unit volume including pores of stone in dry state

this method is suitable for Density Determination of soft stone materials that disintegrate, dissolve, dry shrink and wet swell in water

II. Instruments and materials: hydrostatic balance, flat pan, crane, water container, etc. Paraffin (density is generally 0.93g/cm)

III. sample: preparation number

the stone sample shall be hammered into an irregular shape specimen with a particle size of about 50mm for at least 3 times, or the stone sample shall be made into three cube specimens with a side length of 50mm (or cylinder specimens with a diameter and height of 50mm), washed clean, and marked with the number for standby

IV. test steps:

(1) bake to constant weight and cool to room temperature

put the test piece into the oven and bake it at 105 ± 5 ℃ to constant weight. The drying time is generally 12 ~ 24h. Take it out and put it in the dryer to cool to room temperature

(2) weigh its mass m (accurate to 0.01g/cm)

take out the test piece from the dryer and put it on the balance to weigh its mass m (accurate to 0.01g/cm)

(3) weigh the mass M1 of the paraffin coated test piece

heat and melt the paraffin until it is slightly higher than the melting point (generally the melting point of paraffin is 55-58 ℃), apply a layer of paraffin with a thickness of no more than 1mm on the surface of the stone specimen with a soft brush, and accurately weigh the mass M1 of the specimen coated with paraffin after cooling

(4) tie the test piece coated with paraffin to the balance and weigh its mass in water m2

(5) check the test piece

wipe the moisture on the surface of the test piece, and weigh the mass of the wax sealed test piece again in the air. Check whether the mass of the wax sealed test piece at this time is greater than the mass M1 before immersion. If it exceeds 0.05g, it indicates that the wax seal of the test piece is not good, and the test piece is immersed in water, so the test piece shall be taken for re determination

v. result arrangement: the gross bulk density of stone is calculated according to the formula, with an accuracy of 0.01g/m

where: ρ H - Gross bulk density of stone, g/cm

m - mass of test piece when drying to constant weight, G

m1 - test piece coated with paraffin in air

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