Acoustic-emission testing and diagnostics of the kinetics of physicochemical processes in liquid media

Builo, S. I.; Kuznetsov, Dmitry M.

doi:10.1134/s1061830910090081

“…3). At present, the water-cement paste setting is a well-studied process [5]. It should be noted that in process of further hydration, the amount of free water in the water-cement paste decreases, the stickiness of the gel increases.…”

Section: Resultsmentioning

confidence: 99%

“…Method for registration of the acoustic oscillations induced during the heterophase transitions holding in liquid medium was proposed for the considered processes investigation (method of acoustic emission (AE)). Various authors [2][3][4][5] pay attention to the efficiency of AE-method coupled with optical method and computer simulation of crystals forming during the gypsum CaSO 4 ·0,5Н 2 О and water interaction.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the ultrasonic sound signals during the cementing materials induration

Gaponov

¹

,

Kuznetsov

²

,

Dudnik

³

et al. 2017

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Abstract. The paper is devoted to investigation mechanism of cement mixture setting and stiffening. Method for registration of the acoustic oscillations induced during the heterophase transitions executing in liquid medium was proposed (method of acoustic emission (AE)). Using of conical vessel serving as a resonator allows the amplification of registered acoustic signal and provides high sensitivity of the registration. The experimental results show that the using of AE-method allows remote monitoring of the dynamics of concrete mixtures condition during setting. Therefore, this method can be successfully applied in building as a nondestructive method for determining the start and end of the solidification of the cement solution.

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“…Taking into account the fact that in the described experiments the distortion and superimposition factor of the AE signals was much smaller than unity, the quantitative evaluation of the stream intensity of AE events was determined directly from mea surements of activity (stream intensity of detected AE radio pulses [7]) without recourse to the recov ery procedure (i.e., it was considered that ≈ and N a ≈ ) [7,8]. The statistical treatment of results showed that the recorded intensity of the AE event stream actually drops exponentially and the total number of AE events is accurately described within the framework of the exponentially decaying process model, which is similar to that considered earlier in [2]: (1) where N a is the total number of AE events that occurred by this time t; K is a coefficient that depends on the sensitivity of the AE equipment and acoustic signal recording procedure; m is the total mass of the absorbed liquid by the capillary impregnation process completion; and τ is the relaxation time constant of the impregnation process, which is determined from the emission data in Fig. 2b.…”

mentioning

confidence: 99%

“…

It has been shown in several works that the application of the acoustic emission diagnostic method for studying the kinetics of different physicochemical processes in liquid media is promising [1][2][3][4][5].The purpose of the present work is to analyze the time history of the quantity of AE events in the pro cess of capillary liquid flow in porous media for the interdisciplinary expansion of the application area of the effects of emissions and the creation of a physical nondestructive testing method for the impregnation depth and completeness of materials from parameters of the accompanying acoustic emissions.Until the present time, experimental studies of the dynamics of liquid flows in capillaries were basically performed via optical methods using transparent materials [6]. The known Haines jumps effect can act as a theoretical substantiation of the possibility of using the AE method for the determination of the dynam ics of capillary liquid flows.

…”

mentioning

confidence: 99%

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Acoustic emission testing of capillary liquid flows in porous media

Builo

¹

,

Kuznetsov

²

,

Gaponov

³

2014

Russ J Nondestruct Test

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It has been shown in several works that the application of the acoustic emission diagnostic method for studying the kinetics of different physicochemical processes in liquid media is promising [1][2][3][4][5].The purpose of the present work is to analyze the time history of the quantity of AE events in the pro cess of capillary liquid flow in porous media for the interdisciplinary expansion of the application area of the effects of emissions and the creation of a physical nondestructive testing method for the impregnation depth and completeness of materials from parameters of the accompanying acoustic emissions.Until the present time, experimental studies of the dynamics of liquid flows in capillaries were basically performed via optical methods using transparent materials [6]. The known Haines jumps effect can act as a theoretical substantiation of the possibility of using the AE method for the determination of the dynam ics of capillary liquid flows. The physical nature of Haines jumps is as follows. When the capillary flow in a corrugated capillary is volumetric, the meniscus must periodically stretch and shrink in the capillary expansions and contractions, respectively. The liquid penetration in the porous object generates a growing percolation cluster, whose expansions occur in irregular jumps that are related to filling the pockets of large radius pores (as compared with the radius of the narrow neck, which connects the pocket to the clus ter). In this case, the meniscus assumes a form that is far from equilibrium. The meniscus passes these places very rapidly. This phenomenon is called Haines jumps. It is specified by the pressure fluctuations in a liquid during impregnation and drainage, accompanied by the corresponding energy dissipation and thus should be accompanied by acoustic radiation of the recorded level.The block diagram of the experiment is shown in Fig. 1. The ceramic sample (in our case, a porous alu minooxide carrier, Al 2 O 3 ) is hung in a liquid so that the sample edge adjoins the liquid level, leading to capillary impregnation. During the impregnation, the induced AE waves reached reservoir walls and were observed by sensitive piezosensors. The AE signals that were received by the transducer were amplified by a preamplifier and next applied along the cable to the input of the A Line 32D digital measuring complex (Interunis Co.). Before and after the impregnation, the sample was weighed on a precise scale. The tem perature of the solution and the sample were monitored using an infrared imager.In the course of the experiments the energy, E a , of the AE signals was recorded relative to some thresh old level, activity (number per time unit), and the sum of the AE pulses N Σ [7]. The results of one of the experiments are shown in Fig. 2. It is clear that the parameters of the AE sig nals in the process of the capillary liquid flowing in the porous medium exponentially decay with time. Let us consider the time history of the stream intensity (i.e., the number per time unit) of AE events = dNa/...

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