RU2301786C2 - Method of protecting porous materials against moisture penetration - Google Patents

Abstract

FIELD: manufacture of building materials.

SUBSTANCE: invention is designed for damp-proofing, restoration of destroyed moisture protection during repair and restoration of materials, buildings, and constructions, including historical ones. The whole volume of material is impregnated with hydrophobizing solution at a specified depth while controlling impregnation depth and thereby prolonging lifetime of material owing to lack of process holes in material being impregnated. Penetration of moisture is prevented by introducing hydrophobizer into bulk of material with the aid of pressure created through ultrasonic vibrations in the first Fresnel zone, ultrasonic vibrations being characterized by pulse duration 1-100 μsec, pulsing rate 1-100 μsec, ultrasonic vibration frequency 20-300 kHz, and electrical voltage on converter 1 to 2000 v. A gap between mixture being impregnated and piezoelectric converter surface constitutes 1/4 length of ultrasonic wave in solution and additionally receives ultrasonic vibrations from opposite side of material. Ultrasonic vibration propagation time tuvp is measured in dry and completely impregnated material and control of time of material filling to a specified depth tx(H) is determined from formula characterizing dependence of this parameter on (i) calculated value of ultrasonic vibration propagation time in material being impregnated at the specified depth, (ii) ultrasonic vibration propagation time in dry material, (iii) filling depth of material with solution, and (iv) length of mixture filled with solution. Equation is provided for calculation of coefficient K taking into account maximum ultrasonic vibration propagation time in dry material; minimum ultrasonic vibration propagation time in dry material; maximum ultrasonic vibration propagation time in completely impregnated material; and minimum ultrasonic vibration propagation time in completely impregnated material. Calculated value of ultrasonic vibration propagation time through material being impregnated is compared with specified time value, with time value calculated according to proposed formula, time value corresponding to given impregnation depth. If time values coincide, impregnation operation is stopped, if not, operation is continued.

EFFECT: increased moisture protection degree.

1 tbl, 6 dwg

Description

The invention relates to the field of construction and can be used for waterproofing, restoration of impaired moisture protection during the repair and restoration of materials, buildings and structures, including historical ones.

A known method of protecting the old masonry from moisture absorption, designed to repair the old masonry and the manufacture of horizontal barriers from groundwater (German patent, No. 2237999). The method is characterized in that holes are drilled through the material, practically to the entire depth, at a predetermined distance from each other, a silicate solution is injected into the holes under the action of a pump, and then pressed with a cement slurry.

The main disadvantages of the method are: weakening of the structural strength, the appearance of additional microcracks in the treated area, as well as the inability to achieve uniformity of filling with a hydrophobic solution of the entire volume of the impregnated material.

The closest analogue to the invention is a method for protecting building structures from groundwater (RU No. 2228411, ЕВВ 1/64, 11/10/2003), selected as the prototype.

According to this method, using a pressure field, a water repellent agent is introduced into the wall thickness, the pressure field is created by ultrasonic vibrations in the first Fresnel zone, while the ultrasonic field is created using radio pulses with a duration of 10-40 μs, a power of 100-200 W, and a duty cycle of 5-30 and a filling frequency of 20-70 kHz, which is converted by ultrasonic vibrations, and the magnitude of the vibration parameters is determined by the dimensions and properties of the processed building structure, while the gap between the active The surface of the transducer and the vertical plane of the building structure is 5-10 mm.

The disadvantages of the prototype are: violation of the integrity of the impregnated material, the appearance of microcracks in the treated area, the lack of control of the depth of penetration of the solution into the material.

The objective of the invention is to increase the degree of protection of porous materials from moisture penetration due to impregnation with a hydrophobizing solution of the entire volume of impregnated material or to a predetermined depth, monitoring the depth of impregnation and increasing the service life of the impregnated material due to the absence of technological holes in the impregnated material.

The problem is achieved in that in the method of protecting porous materials from moisture penetration, at which, using the pressure created by ultrasonic vibrations in the first Fresnel zone, a water repellent agent is introduced into the thickness of the material, ultrasonic vibrations have a pulse duration of 1 ... 100 μs, a parcel frequency of 1 ... 100 microseconds, the frequency of 20-300 kHz ultrasonic waves, an electric voltage on the transducer 1 ... 2000 B, and the gap between impregnating material and the active surface of the piezoelectric transducer is _^1/4 dl us ultrasonic wave in the hydrophobizing solution further comprises receiving ultrasonic vibration from the opposite side of the impregnated material is measured and the propagation time of ultrasonic vibration t _edited in a dry and a fully saturated material, control time filling material to a predetermined depth t _x (H) is determined by the formula:

where t _x (H) is the calculated value of the propagation time of ultrasonic vibrations in the impregnated material at a given depth;

t ₀ - propagation time of ultrasonic vibrations in dry material;

H is the depth of filling the material with the solution;

L is the length of the material to be filled with the solution;

- максимальное время распространения ультразвуковых колебаний в сухом материале;

- the maximum propagation time of ultrasonic vibrations in dry material;

- минимальным время распространения ультразвуковых колебаний в сухом материале;

- minimum propagation time of ultrasonic vibrations in dry material;

- максимальное время распространения ультразвуковых колебаний в полностью пропитанном материале;

- the maximum propagation time of ultrasonic vibrations in a completely saturated material;

- минимальное время распространения ультразвуковых колебаний в полностью пропитанном материале,

- the minimum propagation time of ultrasonic vibrations in a completely saturated material,

then the measured value of the propagation time of ultrasonic vibrations through the impregnated material is compared with a predetermined value calculated according to the above formula corresponding to a given depth of impregnation, if the time is the same, then the impregnation process is stopped, if it differs from the preset time, the impregnation process is continued.

The essence of the invention is illustrated in figures 1-6, where

figure 1 is a diagram of the impregnation and control of the depth of filling of the material with a water repellent;

figure 2 - the average value of the time (t) filling a brick with a length of L = 12 cm water repellent to a depth (H) in an acoustic field;

figure 3 - the average value of the time (t) filling the brick L = 12 cm with a water repellent in an acoustic field at different frequencies (20 - 300 kHz);

figure 4 - the average value of the time (t) filling the brick L = 12 cm with a water repellent in an acoustic field with a pulse duration of the probe signal (1 ... 100 μs);

figure 5 - the average value of the time (t) filling the brick L = 12 cm with a water repellent in an acoustic field at a frequency of parcels (time value between pulses) of the pulse of the probe signal (1 ... 100 μs);

6 is a diagram for calculating the time t _x (H) of the impregnation of the material to a depth of N.

A method of protecting porous materials from moisture penetration is carried out using a device consisting of a transducer 1 (Fig. 1), which is attached to one side of the porous material 2, between the transducer 1 and the impregnated material 2 there is a rubber gasket 3, fixing the gap between the material 2 and the active surface transducer 1, and is _^1/4 the length of the ultrasonic wave in water repellents, resulting gap is filled hydrophobizator 4, covering the active surface of the transducer 1, the control depth etc. feed the material with a water repellent agent using a receiving transducer 5, which is mounted on the opposite side of the impregnated material 2, the output of which is connected to the input of the receiver 6, the output of which is connected to the input of the generator 7, the output of which is connected to the input of the transducer 1. Pulses of ultrasonic vibrations from the transducer 1, passed through the impregnated material 2 to the receiving Converter 5 are received by the receiver 6.

Under the influence of pressure created by ultrasonic vibrations using a generator 7 that generates ultrasonic pulses, the pulse duration is 1 ... 100 μs, the frequency of the packets is 1 ... 100 μs, the frequency of ultrasonic vibrations is 20-300 kHz, the voltage on the transducer 1 1. ..2000 B, the porous material 2 is filled with hydrophobizing agent 4, and at the same time, ultrasonic pulses are transmitted through the impregnated material 2 to the receiving transducer 5, they are received by the receiver 6, and the distribution time is analyzed elimination of ultrasonic vibrations.

As a result of experimental studies of the time of filling the porous material with a solution during "ultrasonic impregnation", the dependences of the time of filling the porous material with a hydrophobic solution on the amplitude of the probe pulse and on the frequency f have been _infiltrated . During experimental verification, a brick sample was used as the test material; density 2.9 × 10 ³ kg / m ³ , average grain size 0.5 mm, average capillary diameter 0.05 mm, porosity 17%, as a water repellent agent, the silicone-based GIFOB solution with a density of 1.07 × 10 ³ kg / m ³ .

It was established that during the process of "ultrasonic impregnation" with an increase in the amplitude of the probe pulse U _{rz, the} time of filling the material with solution (t) decreases, measurements were carried out at 1 - U _rz = 100 V, 2 - U _rz = 370 V, 3 - U _rz = 780 In (figure 2), over U _rz = 2000 V - is not economically profitable. However, for small amplitudes U _pz = 100 V, the dependence of the time t of filling the sample to a depth H with a solution is nonlinear. The dependences of the filling time t on the depth H can be divided into three characteristic areas:

- I region - after processing in the surface layer, with a thickness of 1 ... 5 μm, the material is densified throughout the volume, which inhibits the further process of filling it with a solution;

- II region - an almost linear dependence of t (H) is observed;

- III region - there is a slowdown in the filling process, which is explained by an increase in the attenuation of ultrasonic vibrations in the region preceding this region.

An analysis of the dependences of the time of filling a porous material with a solution on the frequency of ultrasonic vibrations shows that the time of complete filling of the sample increases with increasing frequency of the acoustic signal, since an increase in the frequency leads to a weakening of the amplitude with distance, for example, at 1 - f = 20 kHz, 2 - f = 100 kHz, 3 - f = 300 kHz (figure 3). However, at the initial time, the filling rate of the material is proportional to the frequency of ultrasonic vibrations.

The results of theoretical and experimental studies carried out in the work allow us to draw the following conclusions.

1. The application of the ultrasonic filling method allows to increase the depth of filling with a solution without violating the integrity of the material, ensures uniformity of filling.

2. The intensity of filling the brick increases with increasing amplitude of ultrasonic vibrations.

3. The time of complete filling of a brick with a solution increases with an increase in the frequency of ultrasonic vibrations, which is due to the attenuation of the acoustic signal with the depth of filling of the brick.

The effect of the pulse duration of the probe signal on the time of filling the material with a solution is established. As an example, values are given for a sample made of refractory. The results show that the time of complete filling of the material with a pulse duration of 1 - 1 μs, 2 - 50 μs, 3 - 100 μs with a solution (figure 4);

- with a pulse duration of 100 μs, at the initial time, the filling speed of the material is higher (time value is lower) than with a value of duration> 100 μs, however, at short distances there is a possibility of the occurrence of "standing waves" that slow down the speed (the value increases time) full filling of the material,

- at a pulse duration of 1 μs, the filling rate is the lowest.

The influence of the frequency of the bursts (the time between bursts of pulses - period) of the pulse of the probe signal on the time of filling the material with the solution is established.

As an example, values are given for a sample made of refractory. The results show that the time of complete filling of the material with the solution at a time between the pulse transmissions of 1 - 1 μs, 2 - 50 μs, 3 - 100 μs (Fig. 5).

- when the pulse sending frequency is 1 μs, at the initial moment of time the material filling speed is higher (time value is lower) than when the duration is <1 μs, however, at short distances there is a possibility of the occurrence of "standing waves" that slow down the speed (increases value of time) full filling of the material,

- at a pulse duration of 100 μs, the filling rate is the lowest.

Experimentally obtained results on the selection of the optimal gap between the active part of the transducer and the filled material filled with the solution is 1/2 and 1/4 of the ultrasonic wavelength propagated in the filled solution, which corresponds to an organosilicon solution With _l = 1600 m / s, at a frequency 20 kHz, 4 cm and 2 cm, respectively. However, when impregnated with a gap of 1/2 material with a porosity of less than 2%, cavitation occurs, which is an unacceptable phenomenon for this method of impregnation and control of the depth of filling.

In connection with the foregoing, when choosing the optimal gap between the active part of the transducer and the material to be filled with the solution, a gap equal to 1/4 of the length of the ultrasonic wave propagated in the filled solution was chosen, with a gap equal to 1/8 of the length of the ultrasonic wave propagated in filled solution, the filling time is significantly reduced, compared with a gap equal to 1/4 of the length of the ultrasonic wave.

и минимальным

значениями времени до и значениями

,

после пропитки партии материала раствором на глубину H=L выражениями:To determine the required time t _x (H) of impregnation of dry material of length L to a given depth H, the methodology of regression analysis is used (Fig.6); the time t _x (H) of the impregnation of the material to a depth of H is calculated from the measured value of the time t _{0 of the} propagation of ultrasonic vibrations in dry material, which is interconnected with the measured maximum

and minimal

times to and values

,

after impregnating a batch of material with a solution to a depth of H = L by the expressions:

where t _x (H) is the calculated value of the propagation time of ultrasonic vibrations in the impregnated material at a given depth;

t ₀ - propagation time of ultrasonic vibrations in dry material;

H is the depth of filling the material with the solution;

L is the length of the material to be filled with the solution;

- максимальное время распространения ультразвуковых колебаний в сухом материале;

- the maximum propagation time of ultrasonic vibrations in dry material;

- минимальным время распространения ультразвуковых колебаний в сухом материале;

- minimum propagation time of ultrasonic vibrations in dry material;

- максимальное время распространения ультразвуковых колебаний в полностью пропитанном материале;

- the maximum propagation time of ultrasonic vibrations in a completely saturated material;

- минимальное время распространения ультразвуковых колебаний в полностью пропитанном материале.

- the minimum propagation time of ultrasonic vibrations in a fully impregnated material.

,

и

,

.Studies have shown that the discrepancies Δt _{in the} calculated and experimental data on the determination of the time t _x (H) of the propagation of ultrasound through a material of length L, impregnated to a depth of H, do not exceed 3% (table). This makes it possible to predetermine the propagation time of ultrasound in the material depending on the depth H of filling the material with the solution according to the measured time t _{0 of the} propagation of ultrasound in the material until it is impregnated and the previously obtained experimental values

,

and

,

.

Table 0 one 2 3 four 5 6 7 8 9 10 eleven 12 t _min , μs 43,47 43.01 42.11 41.23 40.81 40.81 40.41 40.12 39.27 38.91 37.62 37.15 35.92 t _max , μs 51.55 49.58 46.69 45.28 44.77 44,44 43.32 43.01 42.11 41.37 39.86 39.06 37.73 t _ISM 46.87 45.28 44.28 43.16 42.71 42.55 41.81 41.53 40.67 40.13 38.70 38.09 36.92 t _calculation , μs 46.87 46.05 45.24 44,44 43.63 42.82 42.01 41.20 40.39 39.58 38.77 37.96 36.63 Δt _burr (%) 0 1,67 2.16 2.96 2.15 0.63 0.47 0.79 0.68 1.37 0.18 0.34 0.08

The results of theoretical and experimental studies allow us to draw the following conclusions:

1. The propagation time of longitudinal elastic waves in dry and impregnated material is determined by the elasticity of the skeleton of the material, porosity and its lithological features, as well as the elastic characteristics of the hydrophobizing solution. This necessitates the experimental determination of the propagation time of elastic waves in the studied material of each type in a dry and solution-saturated state.

2. Using the methodology of the proposed calculation allows you to determine the change in the propagation time of ultrasonic vibrations in the material depending on the depth of its filling with the solution.

Then, the measured value of the propagation time of ultrasonic vibrations through the impregnated material t _{ism is} compared with a predetermined, calculated t _x (H) according to the above formula, the time value corresponding to a given depth of impregnation, if the time coincides, then a signal is received from receiver 6 (Fig. 1) generator 7 about completion of the impregnation process, stop the operation, if it differs from the set time, then the impregnation process continues.

Claims (1)

A method of protecting porous materials from moisture penetration, in which, using the pressure created by ultrasonic vibrations in the first Fresnel zone, a water repellent agent is introduced into the thickness of the material, characterized in that the ultrasonic vibrations have a pulse duration of 1-100 μs, a sending frequency of 1-100 μs, a frequency ultrasonic vibrations of 20-300 kHz, the voltage at the transducer is 1-2000 V, and the gap between the impregnated material and the active surface of the piezoelectric transducer is 1/4 of the ultrasonic wavelength water-repellent solution, additionally accept ultrasonic vibrations from the opposite side of the impregnated material, and measure the propagation time of ultrasonic vibrations t _ISM , in a dry and completely saturated material, control the time of filling the material to a given depth t _x (H) is determined by the formula

where t _x (H) is the calculated value of the propagation time of ultrasonic vibrations in the impregnated material at a given depth; t ₀ - propagation time of ultrasonic vibrations in dry material; H is the depth of filling the material with the solution; L is the length of the material to be filled with the solution;

Where

- the maximum propagation time of ultrasonic vibrations in dry material;

- the minimum propagation time of ultrasonic vibrations in dry material;

- the maximum propagation time of ultrasonic vibrations in a completely saturated material;

- the minimum propagation time of ultrasonic vibrations in a completely saturated material, then the measured value of the propagation time of ultrasonic vibrations through the impregnated material is compared with a predetermined time calculated according to the above formula, corresponding to a given depth of impregnation, if the time is the same, then the impregnation process is stopped, if it differs from the preset time, the impregnation process is continued.

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