CN104596878A - Method and test steps for testing water absorption capacity of porous stone in fresh concrete - Google Patents

Abstract

The invention relates to a testing method and test steps for testing the water absorption amount of porous stone in fresh concrete. First, the test data in each step is measured through test steps such as stone drying, water immersion, and wax sealing, and then the total mass of water absorbed by the stone itself and water saturated in the pores is calculated through the formula derived by the present invention. This solves the problem that when porous stones are used in cement concrete, the unit water consumption in fresh cement concrete cannot be accurately determined because the stones absorb water and the gaps are saturated with water.

Description

Water absorption test method and test procedure of porous stone in fresh concrete

technical field

The invention relates to a test method and test steps for testing the water absorption of porous stone in fresh concrete, belonging to the field of transportation engineering.

Background technique

With the continuous acceleration of highway and urbanization construction, and the rapid development of the construction industry, the demand for crushed stone for concrete is increasing day by day. However, due to the uneven distribution of rocks and pebbles, there is a shortage of artificial gravel and pebbles in some areas. Therefore, based on the principles of local materials, environmental protection, and local conditions, porous stone materials (such as porous basalt, steel slag, recycled aggregate, etc.) have also been more and more widely used.

When porous stone is used to mix cement concrete, in addition to the stone absorbing part of the water, the voids in the stone itself will also absorb and store a certain amount of water. Therefore, in the process of preparing cement concrete, when calculating the unit water consumption, the additional water consumption due to the water absorption of the stone and the water storage in the voids should be included in this part, otherwise the water consumption for cement hydration will be reduced, affecting The hydration of cement affects the formation of cement concrete strength.

However, the existing aggregate water absorption test methods (such as the surface dry method) only consider the water absorption of the aggregate, and do not consider that the voids of the stone will absorb the stored moisture when mixing cement concrete.

Contents of the invention

In order to overcome the deficiency that the existing stone water absorption test method cannot accurately measure the water absorption (rate) when porous stone is used in fresh concrete, the present invention proposes a test method and test procedure for the water absorption of porous stone in fresh concrete , this method can effectively measure the water absorption (stone water absorption + pore saturation) of porous stone in fresh concrete.

In order to achieve the above tasks, the technical solutions proposed by the present invention are as follows.

(1) For a piece of stone with a certain particle size or a piece of aggregate selected according to the gradation requirements, weigh its mass in the natural state, m ₁ ; then dry the stone in an oven at 105°C±5°C until Constant weight, weigh the mass of the stone in dry state, m ₂ .

(2) Take a 2000mL volumetric flask (it can also be replaced by a ground-mouthed wide-mouth glass bottle), add water to the bottle to 1/2, then put the dried stones into the bottle, shake the volumetric flask lightly or stir with a glass rod Stone material, so that all the air bubbles attached to the bottle wall and stone material escape, and then fill the bottle with water. Soak at room temperature for 24 hours.

(3) After soaking for 24 hours, add water to the volumetric flask until the water surface protrudes from the mouth of the bottle, slide the glass piece quickly along the mouth of the bottle to make it close to the water surface of the bottle mouth. If air bubbles appear between the glass piece and the mouth of the bottle during sliding, use a dropper to add a small amount of water to the mouth of the bottle to ensure that there are no air bubbles between the glass piece and the water surface. After confirming that there are no air bubbles in the bottle, wipe off the water on the outer wall of the bottle, and then weigh the total mass of the volumetric bottle, stone, water and glass flakes, m ₃ .

(4) Pour all the water and stone in the volumetric bottle into a sieve with a pore size of 2.36mm to filter out water, vibrate the sieve for 2 minutes mechanically or manually, and then dry the attached water on the surface of the stone with a clean wet towel to make the surface After reaching the saturated surface dry state, measure the mass of the stone, m ₄ .

(5) Melt the paraffin to 5.5°C ± 0.5°C above its melting point (the melting point of paraffin is about 58°C), quickly immerse the stones in the paraffin liquid one by one, and take them out quickly, and observe the surface. If there are bubbles, use a needle Dip in paraffin again after puncturing the air bubbles. After all the stones are soaked in paraffin wax, weigh the mass of the stones sealed with wax, m ₅ .

(6) Put the paraffin-coated stone into the volumetric flask, fill up with water according to the method of adding water in step (3), and weigh the mass of the volumetric flask, the wax-sealed stone, water and glass flakes, m ₆ .

(7) Use the following formula to calculate the total water absorption mass m of the stone:

.

Compared with the existing method for testing the water absorption rate of stones, the method of the present invention has the advantage that the water that the voids of the stones will absorb and store during the mixing process of the fresh cement concrete can be considered, and the entire volume of the porous stones in the cement concrete can be accurately measured. Water absorption (stone water absorption + pore saturation), so as to accurately calculate the additional water consumption required to prepare cement concrete.

Detailed ways

The present invention will be further described in detail below by taking the water absorption test of recycled aggregate produced by crushing old cement concrete as an example. It should be noted that the following examples are only preferred examples of the present invention, and do not limit the present invention in any way. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

(1) Select a recycled aggregate with a particle size of 19mm, weigh its mass in the natural state, m ₁ ; then dry it in an oven at 105°C±5°C to constant weight, weigh the recycled aggregate and dry it Mass in state, m ₂ .

(2) Take a 2000mL volumetric flask (can also be replaced by a ground-mouthed wide-mouth glass bottle), add water to the bottle to 1/2, then put the dried recycled aggregate into the bottle, shake the volumetric flask gently or use a glass Stir the recycled aggregate with a stick to make all the air bubbles attached to the bottle wall and the recycled aggregate escape, and then fill the bottle with water. Soak at room temperature for 24 hours.

(3) After soaking for 24 hours, add water to the volumetric flask until the water surface protrudes from the mouth of the bottle, slide the glass piece quickly along the mouth of the bottle to make it close to the water surface of the bottle mouth. If air bubbles appear between the glass piece and the mouth of the bottle during sliding, use a dropper to add a small amount of water to the mouth of the bottle to ensure that there are no air bubbles between the glass piece and the water surface. After confirming that there are no air bubbles in the bottle, wipe off the water on the outer wall of the bottle, and then weigh the total mass of the volumetric bottle, recycled aggregate, water and glass flakes, m ₃ .

(4) Pour all the water and recycled aggregate in the volumetric flask into a sieve with a pore size of 2.36 mm to filter out water, use a manual vibrating screen for 2 minutes, and then dry the attached water on the surface of the recycled aggregate with a clean wet towel to make it When the surface reaches a saturated surface-dry state, measure the mass of the recycled aggregate, m ₄ .

(5) Melt the paraffin to 63°C±0.5°C, quickly immerse the recycled aggregate in the paraffin liquid one by one, and take it out quickly, observe its surface, if there are bubbles, pierce the bubbles with a needle and dip in paraffin again. After all the recycled aggregates are soaked in paraffin wax, weigh the mass of the recycled aggregates sealed with wax, m ₅ .

(6) Put the recycled aggregate coated with paraffin into the volumetric flask, fill up the water according to the method of adding water in step (3), weigh the mass of the volumetric flask, recycled aggregate after wax sealing, water and glass flakes, m ₆ .

(7) Use the following formula to calculate the total water absorption mass m of the stone:

.

See Table 1 for the various masses weighed in the above steps (1) to (7) and the calculation results of the water absorption of the stone.

Table 1 Weighing mass and stone water absorption calculation results during the test (unit: g)

m ₁ m ₂ m ₃ m ₄ m ₅ m ₆ m 887.1 859.3 2236.9 898.7 941.2 2228.0 44.0

Claims (2)

1., for testing method of testing and the test procedure of porous building stones water absorbing capacity in fresh concrete, it is characterized in that, described test procedure comprises:

(1) for a building stones of a certain particle diameter or gather materials by the portion that grating requirement is chosen, quality under its state of nature is taken, m ₁; Again by building stones as drying to constant weight in the baking oven of 105 DEG C ± 5 DEG C, take the quality under building stones drying regime, m ₂;

(2) 2000mL volumetric flask (also can replace with the wide mouth glass bottle of ground) is got, 1/2 place is added water in bottle, then the building stones of oven dry are put into bottle, jog volumetric flask or stir building stones with glass bar, the bubble be attached on bottle wall and building stones is all overflowed, again to topped up with water in bottle, under being placed in room temperature, soak 24h;

(3) until immersion after 24 hours, in volumetric flask, add water to the water surface protrude bottleneck, slide rapidly along bottleneck with glass sheet, make it be close to the bottleneck water surface, if there is bubble between glass sheet and bottleneck in taxiing procedures, available dropper adds water on a small quantity to bottleneck, ensure bubble must not be had to exist between glass sheet and the water surface, after confirming there is no bubble in bottle, dry the moisture of bottle outer wall, then the gross mass of volumetric flask, building stones, water and glass sheet is taken, m ₃;

(4) filtering moisture on the sieve water in volumetric flask and building stones being poured into 2.36mm aperture, adopt machinery or manual type to shake sieve 2min again, then dry the attached water of stone surface with clean wet towel, its surface is reached capacity surface dry condition, record building stones quality again, m ₄;

(5) by more than melted paraffin wax to its fusing point 5.5 DEG C ± 0.5 DEG C (paraffin melting point is about 58 DEG C), building stones are immersed in paraffin liquid rapidly by grain, and take out rapidly, observe its surface, if any bubble, then paraffin again after pricking a bubble with pin, after whole building stones have soaked paraffin, take the building stones quality after sealing with wax, m ₅;

(6) putting into volumetric flask by wrapping the building stones after paraffin, by the water feeding method topped up with water of preceding step, taking volumetric flask, seal with wax after the quality of building stones, water and glass sheet, m ₆.

2. porous building stones according to claim 1 water absorbing capacity method of testing and test procedure in fresh concrete, is characterized in that, can adopt the total water suction quality m of the porous building stones described in following formulae discovery in fresh concrete:

。