SU1716439A1 - Method of determining communicating concrete porosity - Google Patents

Abstract

The invention relates to the technology of building materials and can be used in research and construction laboratories with the experimental determination of the reported porosity of concrete. The purpose of the invention is to improve the accuracy of determination. Air-wet storage samples are evacuated, saturated with deaerated water. The volume of the communicating pores in the concrete sample is determined by the change in hydraulic pressure in the hermetic vessel where the sample is located. Reported porosity is calculated by the formula. 1 il.

Description

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The invention relates to the technology of building materials and can be used in research and construction laboratories to experimentally determine the associated porosity of concrete.

The purpose of the invention is to improve the accuracy of determination.

The method is carried out using the device shown in the drawing and containing a metal rigid vessel 1 of unchangeable volume at an internal pressure of up to 2 MPa with an airtight lid, a lining 2 of water-unsaturated material (metal, glass) at the bottom of the vessel for placing the test sample 3, taps 4-12, sump 13 for water, mercury manometer 14, mechanical model manometer 15, hard sealed vessel 16,

pressurized vessel 17 - pressurized water feeder, flexible diaphragm 18 made from sheet vacuum plates.

The method is carried out as follows.

A sample of standard air-wet storage (solidified in a chamber with a relative humidity of 0.95-0.98) is used in the form of a cube, cylinder, or irregular debris of approximately 1000 cm. Samples are pre-evacuated in an airtight container with a capacity of approximately 1.5-2 sample volumes.

Evacuation is performed until stabilization in an overpressure system of 1-2 mm Hg. Then, by closing the taps 8 and 9 and opening the taps 4, 6, 7, the vessel 1, the bottom

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the feeder chamber 17, the vessel 16, the left knee of the mercury manometer 14 and the mechanical model pressure gauge 15. In this case, the water pressure is set to close to atmospheric,

After closing the valve 4, the water pressure is raised throughout the system by means of the feeder 17 by running compressed air into the upper chamber of the feeder up to the first pressure Pi, which is fixed by manometers 14 and 15, equal to approximately 0.01 MPa (excess pressure values). After that, valve b is closed and air pressure in the feeder increases the pressure of water in vessel 1 to a pressure of 1-2 MPa, valve 7 is closed, and pressure in vessel 1 is stabilized according to pressure gauge 15. Pressure stabilization indicates that the sample is saturated with water. Depending on the structure of the pore space of the sample, saturation extends from 0.5 to 8 hours.

The pressure established in vessel 1 is measured with a pressure gauge 15 with an accuracy of 0.002 MPa and recorded. Then the valve 6 is opened, as a result of which the pressure in the vessel 16 rises, and in the vessel 1 it decreases, and the total value is fixed, fixed by gauges 14 and 15,

After stabilization, record this pressure. This completes the experiment. By opening the valve 11, atmospheric pressure is established throughout the system, the lid of the vessel 1 is opened, the sample is removed and its volume is determined.

The volume of communicating pores in a concrete sample is calculated by the formula

Vnop - V0 + V6-VB.A., Where V0 is the volume of the mass of water;

Ve is the volume of the concrete sample;

VB.A. - the volume of the pressure vessel, and the associated porosity of the concrete - according to the formula

p - OPOR Ps 7G

Formula 8 of the invention and Method. Determine the associated porosity of concrete, including measuring the volume of a sample, saturating it with water under hydrostatic pressure with preliminary evacuation, determining the pore volume, differing in that, in order to improve the accuracy of determination, use samples normal air-wet storage, vacuum them in a sealed vessel of unchangeable volume. MA, saturate with de-aerated water in the same vessel, determine the volume of the communicating pores in the concrete sample by the change in hydrostatic pressure in this vessel, and the associated porosity is calculated by the formula

p - -App PS 7G where PS is the concrete porosity of the concrete;

Vnop is the volume of communicating pores in the concrete sample;

Ve is the volume of the concrete sample.

Claims (1)

Claim The way. determining the communicating porosity of concrete, including measuring the volume of the sample, saturating it with water under hydrostatic pressure with preliminary evacuation, determining the pore volume, distinguished by the fact that, in order to increase the accuracy of determination, samples of normal air-wet storage are used, they are evacuated in a sealed vessel of unchanged volume, saturated with deaerated water in the same vessel, the volume of communicating pores in the concrete sample is determined by the change in hydrostatic pressure in this vessel, and yuschuyusya porosity is calculated by the formula P _s - informing porosity of concrete; Vnop is the volume of communicating pores in the concrete sample; Ve is the volume of the concrete sample. To vacuum pump S squeezed air Water Des aerated Water ~~ 5