CN110736675A - sandstone aggregate saturated surface dry water absorption determination device and method - Google Patents

Abstract

The invention discloses a device and a method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates. The measuring device comprises a temperature and humidity control box, an automatic collection and recording device, a host computer, an electronic balance and a sample tray; The top is provided with a through hole connecting the inside and the outside, the sample pan is connected to the electronic balance through a pull rope, and the pull rope passes through the through hole to hang the sample pan on the temperature and humidity control box Internally, the electronic balance is connected with the automatic collection and recording device, and the automatic collection and recording device is connected with the host computer. The advantages are: it can accurately determine the dry state of the saturated surface of the sand, the degree of automation is high, it is not affected by the operator, and the test result is highly accurate.

Description

A kind of sand and gravel aggregate saturated surface dry water absorption measuring device and method

technical field

The invention relates to the technical field of civil engineering, in particular to a device and method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates.

Background technique

The saturated surface dry water absorption of sand and gravel is an important reference parameter for evaluating the quality characteristics of concrete aggregates and the design of concrete mix ratio. The saturated surface dry state refers to the state in which the pores that can be penetrated by water in the sand and gravel particles are filled with water, but there is no free water on the surface of the particles.

At present, there are two methods for measuring the dry water absorption rate of the saturated surface of sand and gravel. There are mold test method and wet mark method. Since the dry state of the saturated surface of sand and gravel is a critical state, it is not easy to judge and easy to miss. The existing measurement methods have large errors and are time-consuming. It requires the testing personnel to have rich testing experience.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device and method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates, so as to solve the aforementioned problems existing in the prior art.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A device for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregate, the measuring device comprises a temperature and humidity control box, an automatic collection and recording device, a host computer, an electronic balance and a sample tray; The sample pan is connected to the electronic balance through a pull rope, and the pull rope passes through the through hole to hang the sample pan inside the temperature and humidity control box, and the electronic balance With the automatic collection and recording device, the automatic collection and recording device is connected with the upper computer.

Preferably, the bottom of the electronic balance is provided with a hook, and one end of the drawstring away from the sample tray is connected to the hook.

Preferably, the range of the electronic balance is not less than 5.0kg, and the precision of the electronic balance is not less than 0.01g.

Preferably, there is a certain distance between the pull cord and the circumferential wall of the through hole.

Another object of the present invention is to provide a method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates, which is realized by using any of the above-mentioned measuring devices; the measuring method includes the following steps:

S1, take an appropriate amount of sand and put it into a pretreatment container, and inject clear water into the pretreatment container, so that the water surface is 2cm higher than the sand; and make the sand soak in the clear water for 24h, and the indoor temperature is kept at 20 ° C;

S2. Start the temperature and humidity control box, and control the temperature in the temperature and humidity control box to be 10-80° C. and the relative humidity to be 10%-80%; open the electronic balance, and use the drawstring to hang the sample pan on the on the hook of the electronic balance, and reset the electronic balance;

S3, after the sand is soaked for 24h, the water in the pretreatment container is poured out, and a certain amount of sand is weighed as a sand sample and spread in the sample tray;

S4, start the automatic collection and recording device and the host computer, and start the measurement; after the quality of the sand sample no longer changes, adjust the temperature of the temperature and humidity control box to 105°C, dry the sand sample to a constant weight, and record The quality of the sand sample at this time is G ₀ ;

S5. According to the change of the quality of the sand sample with time, calculate and draw the change curve of the water evaporation rate of the sand sample with time, find out the inflection point time when the water evaporation rate starts to decrease significantly, and record the sand sample quality G ₁ corresponding to the inflection point time;

S6. Calculate the dry water absorption rate T ₀ of the sand saturated surface based on the saturated surface dry sand and the dry water absorption rate T ₁ of the sand saturated surface based on the dry sand.

Preferably, the dry water absorption rate T ₀ of the saturated surface of the sand based on the saturated surface dry sand is calculated by the following formula:

Preferably, the dry water absorption rate T ₁ of the saturated surface of the sand based on dry sand is calculated by the following formula:

The beneficial effects of the present invention are that the measuring device and method provided by the present invention can accurately determine the dry state of the saturated surface of the sand, the degree of automation is high, the operator is not affected, and the test result is highly accurate.

Description of drawings

Fig. 1 is the structural representation of the measuring device in the embodiment of the present invention;

Fig. 2 is the schematic flow chart of the assay method in the embodiment of the present invention;

Fig. 3 is the water loss process curve of limestone artificial sand sand sample in the embodiment of the present invention;

Fig. 4 is the water loss process curve of natural river sand sand sample in the embodiment of the present invention;

Fig. 5 is the water loss process curve of the sandstone artificial sand sample in the embodiment of the present invention.

In the figure: 1. Temperature and humidity control box; 2. Electronic balance; 3. Automatic acquisition and recording device; 4. Host computer; 5. Sample tray; 6. Pull rope; 7. Through hole;

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

As shown in FIG. 1 , a device for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregate is provided in this embodiment. The measuring device includes a temperature and humidity control box 1 , an automatic collection and recording device 3 , a host computer 4 , and an electronic balance 2 and the sample pan 5; the top of the temperature and humidity control box 1 is provided with a through hole 7 that communicates its interior and the outside world, and the sample pan 5 is connected to the electronic balance 2 through a drawstring 6, and the drawstring 6 passes through the The through hole 7 hangs the sample tray 5 inside the temperature and humidity control box 1, the electronic balance 2 is connected with the automatic collection and recording device 3, and the automatic collection and recording device 3 is connected with the host computer 4. .

In this embodiment, the electronic balance 2 is provided with a hook at the bottom, and one end of the pulling rope 6 away from the sample tray 5 is connected to the hook.

In this embodiment, the range of the electronic balance 2 is not less than 5.0kg, and the precision of the electronic balance 2 is not less than 0.01g.

In this embodiment, there is a certain distance between the pull cord 6 and the circumferential wall of the through hole 7 .

In this embodiment, the temperature and humidity control box 1 can adjust the temperature and humidity according to actual needs, and the experimenter can adjust it by himself.

In this embodiment, the electronic balance 2 is arranged on the top upper surface of the temperature and humidity control box 1, so that the electronic balance 2 can measure very smoothly, without tilting to affect the measurement results, and at the same time, it is also convenient to pull the rope 6 Connect to the electronic balance 2 through the through hole 7 smoothly.

In this embodiment, the electronic balance 2 is connected to the automatic collection and recording device 3 through the data line 8, and the automatic collection and recording device 3 can record the mass of the sample in the sample tray 5 measured by the electronic balance 2, and the time corresponding to the mass. , and transmit these data to the upper computer 4.

In this embodiment, the automatic collection and recording device 3 is connected with the host computer 4 through a data line 8, and the host computer 4 is provided with relevant software, which can automatically calculate and draw the data transmitted from the automatic collection and record The curve of the water evaporation rate of the sample as a function of time.

Embodiment 2

As shown in FIG. 2 , this embodiment provides a method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates, which is realized by using a measuring device; the measuring method includes the following steps:

S1, take an appropriate amount of sand and put it into a pretreatment container, and inject clear water into the pretreatment container, so that the water surface is 2cm higher than the sand; and make the sand soak in the clear water for 24h, and the indoor temperature is kept at 20 ° C;

S2. Start the temperature and humidity control box 1, and control the temperature in the temperature and humidity control box 1 to be 10-80° C. and the relative humidity to be 10%-80%; Disk 5 is hung on the hook of described electronic balance 2, and described electronic balance 2 is cleared;

S3, after the sand is soaked for 24h, the water in the pretreatment container is poured out, and a certain amount of sand is weighed as a sand sample and spread out in the sample tray 5;

S4, start the automatic collection and recording device 3 and the host computer 4, and start the measurement; after the quality of the sand sample no longer changes, adjust the temperature of the temperature and humidity control box 1 to 105°C, and dry the sand sample to a constant weight , and record the quality of the sand sample at this time as G ₀ ;

S5. According to the change of the quality of the sand sample with time, calculate and draw the change curve of the water evaporation rate of the sand sample with time, find out the inflection point time when the water evaporation rate starts to decrease significantly, and record the sand sample quality G ₁ corresponding to the inflection point time; The inflection point time when the evaporation rate starts to decrease significantly is the time when the sand reaches the saturated surface dry;

S6. Calculate the dry water absorption rate T ₀ of the sand saturated surface based on the saturated surface dry sand and the dry water absorption rate T ₁ of the sand saturated surface based on the dry sand.

In this embodiment, the dry water absorption rate T ₀ of the saturated surface of the sand based on the saturated surface dry sand is calculated by the following formula:

In the present embodiment, the dry water absorption rate T1 _of the saturated surface of the sand based on dry sand is calculated by the following formula:

In this embodiment, the pretreatment container may use a container such as an enamel plate.

In this embodiment, the determination of the dry state of the saturated surface of the sand adopts the following principle: under constant temperature and humidity conditions, the water evaporation rate of the sand in the saturated state is mainly affected by the specific surface area of the particles, the surface water content, the particle pore structure and the surface structure. The water loss process is divided into the surface water loss stage and the pore water water loss stage. For a certain amount of water-saturated sand, its specific surface area remains unchanged, and the water evaporation rate is basically constant during the surface water loss stage. In the saturated surface dry state, the water evaporation is affected by capillary action, and the evaporation rate will be significantly reduced, that is, the saturated surface dry state is determined by the change point of the sand water evaporation rate.

Embodiment 3

As shown in FIGS. 3 to 5 , in this embodiment, the sand used is limestone artificial sand, which is measured according to the measuring device of the first embodiment and the measuring method of the second embodiment, and the measurement results are shown in Table 1. The dry water absorption rate of the sand saturated surface in this example was measured according to the method for determining the dry water absorption rate of the saturated surface of the sand (testing method) specified in the current national standard, and the results are shown in Table 1.

In this embodiment, the sand used is natural river sand, which is measured according to the measuring device in the first embodiment and the measuring method in the second embodiment, and the measurement results are shown in Table 1. The dry water absorption rate of the sand saturated surface in this example was measured according to the method for determining the dry water absorption rate of the saturated surface of the sand (testing method) specified in the current national standard, and the results are shown in Table 1.

In this embodiment, the sand used is sandstone artificial sand, which is measured according to the measuring device of the first embodiment and the measuring method of the second embodiment, and the measurement results are shown in Table 1. The dry water absorption rate of the sand saturated surface in this example was measured according to the method for determining the dry water absorption rate of the saturated surface of the sand (testing method) specified in the current national standard, and the results are shown in Table 1.

Table 1

In this embodiment, the measurement is performed according to the type of sand, and the change curve of the water evaporation rate of the sand sample with time is calculated and drawn according to the change of the quality of the sand sample with time. The graphs are shown in Figures 3 to 5.

By adopting the above-mentioned technical scheme disclosed by the present invention, the following beneficial effects are obtained:

The invention provides a device and method for measuring the dry water absorption rate of the saturated surface of sand and gravel aggregates. The measuring device and method can accurately determine the dry state of the saturated surface of sand, with a high degree of automation, no operator influence, and high test result accuracy.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. The device for measuring the saturated surface dry water absorption of sandstone aggregates is characterized by comprising a temperature and humidity control box, an automatic acquisition and recording device, an upper computer, an electronic balance and a sample disc, wherein a through hole for communicating the inside of the temperature and humidity control box with the outside is formed in the top of the temperature and humidity control box, the sample disc is connected with the electronic balance through a pull rope, the pull rope penetrates through the through hole to hang the sample disc in the temperature and humidity control box, the electronic balance is connected with the automatic acquisition and recording device, and the automatic acquisition and recording device is connected with the upper computer.
2. 2. The sandstone aggregate saturated surface dry water absorption measurement device of claim 1, wherein the bottom of the electronic balance is provided with a hook, and the end of the pull rope far away from the sample disc is connected with the hook.
3. 3. The sandstone aggregate saturated surface dry water absorption measurement device of claim 2, wherein: the measuring range of the electronic balance is not less than 5.0kg, and the precision of the electronic balance is not less than 0.01 g.
4. 4. The sand aggregate saturated surface dry water absorption measuring device according to claim 3, wherein the distance between the pulling rope and the circumferential wall of the through hole is mm.
5. A method for measuring the saturated surface dry water absorption of sand aggregates, which is carried out by using the measuring apparatus of any of the above claims 1 to 4, , characterized in that the method comprises the steps of,

   s1, taking a proper amount of sand, filling the sand into a pretreatment container, and injecting clear water into the pretreatment container to enable the water surface to be 2cm higher than the sand; soaking the sand in clear water for 24 hours, and keeping the indoor temperature at 20 ℃;

   s2, starting a temperature and humidity control box, and controlling the temperature in the temperature and humidity control box to be 10-80 ℃ and the relative humidity to be 10-80%; opening the electronic balance, hanging the sample tray on a hook of the electronic balance by using the pull rope, and resetting the electronic balance;

   s3, after sand is soaked for 24 hours, pouring out water in the pretreatment container, weighing quantitative sand as a sand sample, and flatly spreading the sand sample in the sample tray;

   s4, starting the automatic acquisition and recording device and the upper computer to start measurement; after the quality of the sand sample does not change any more, adjusting the temperature of a temperature and humidity control box to 105 ℃, drying the sand sample to constant weight, and recording the quality of the sand sample as G₀；

   S5, calculating and drawing a change curve of the moisture evaporation rate of the sand sample along with time according to the change of the sand sample quality along with time, finding out the inflection point time when the moisture evaporation rate begins to obviously decrease, and recording the sand sample quality G corresponding to the inflection point time₁；

   S6, calculating the dry water absorption T of the saturated surface of the sand based on the dry sand of the saturated surface₀And a sand saturated surface dry absorption device taking dry sand as a referenceWater rate T₁。
6. 6. The method for measuring the sand aggregate saturated surface dry water absorption according to claim 5, characterized in that: dry water absorption T of saturated surface of sand based on dry sand of saturated surface₀As calculated by the following formula,

   
7. 7. the method for measuring the sand aggregate saturated surface dry water absorption according to claim 5, characterized in that: dry water absorption T of saturated surface of sand based on dry sand₁As calculated by the following formula,

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