experimentalinvestigationoftheuseofexpansivematerialsto ... · 2020. 7. 31. · described by the...

Research ArticleExperimental Investigation of the Use of Expansive Materials toIncrease Permeability in Coal Seams throughExpansive Fracturing

Xiao Cui12 Jiayong Zhang 12 Liwen Guo12 and Xuemin Gong3

1College of Mining Engineering North China University of Science and Technology Tangshan Hebei 063210 China2Mining Development and Safety Technology Key Lab of Hebei Province Tangshan Hebei 063210 China3College of Chemical Engineering North China University of Science and Technology Tangshan Hebei 063210 China

Correspondence should be addressed to Jiayong Zhang zjy815ncsteducn

Received 4 February 2020 Revised 16 June 2020 Accepted 10 July 2020 Published 31 July 2020

Academic Editor Hongwei Yang

Copyright copy 2020XiaoCui et al-is is an open access article distributed under theCreative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Hydration reactions of expansive materials are typically very safe easy to induce and low in cost while the crushing of suchmaterials is typically free from noise dust vibration and toxic gases In the present study to realize the application of expansivematerials in the prevention of coal seam gas disasters the microstructure heat release rate and expansive pressure of expansivematerials were investigated for different degrees of hydration based on temperature and pressure measurements and using ascanning electron microscope (SEM) fracture characteristics were determined based on fracture tests of coal-like materials -eresults show that the expansive material with +30water has the lowest hydration temperature (100degC)-e expansive pressure ofthe steel tube was found to reach 57MPa which is deemed suitable for application in coal seams -e strain and displacement ofcoal-like materials were found to increase with time with four main cracks appearing Based on these results it is feasible thathydration reactions of expansive materials could increase both gas drainage and permeability in coal seams thus reducing the riskof rock burst around boreholes in coal seams

1 Introduction

-e permeability of coal seams decreases with increasingcoal seam depth leading to simultaneous increases in gascontent and pressure Such processes result in considerablethreat to production safety [1 2] Drilling boreholes in low-permeability coal seams typically results in the discharge ofgas previous studies have shown that optimizing the drillingposition and enlarging the extracting radius can help toimprove coal bed permeability [3 4] Recent developmentsin pressure relief and permeability-increasing technologyinclude hydraulic boreholes hydraulic fracturing intensivedrilling and concussion blasting [5 6] However thesetechnologies have disadvantages they are often labor in-tensive and require long construction periods and consid-erable financial investment -erefore investigating newpressure relief and permeability-increasing technology isimportant

In the context considered here expansive materials aregel-like cement materials that react with water and crys-tallize into the solid phase resulting in an increase in theirvolume -e crystallization process exerts pressure onborehole walls resulting in rock burst around the boreholewhen the expansive pressure and vertical tensile stress ex-ceed the tensile strength of the surrounding brittle materials[7 8] In an early study expansive cement was produced bygrinding ettringite and gypsum calcining them at 1500degCand adding a proportion of finely ground slag [9] A sub-sequent study increased the calcination temperature ofcalcium oxide and obtained an expansive material con-taining calcium sulfate and calcium oxide [10] Expansivematerials have also been developed by mixing calcium oxideand water in a borehole this in situ hydration of quicklimewas found to double the volume of material in the boreholeresulting in fracturing due to expansive pressure [11] Effortsto develop expansive materials in China were initiated in the

HindawiShock and VibrationVolume 2020 Article ID 7925724 11 pageshttpsdoiorg10115520207925724

1950s Early efforts investigated the sintering of high-alu-minum cement with a rotary kiln and provided importantguidance for future investigation of expansive materials [12]while a self-stressing silicate cement was developed suc-cessfully in 1957 A later study investigated the viability ofusing calcium oxide calcined at high temperature as anexpansive source based on analysis of the reaction mech-anisms of the expansive material and on laboratory ex-periments and industrial testing and developed anexpansive crushing agent with a reaction pressure that canexceed 60MPa [13] Expansive materials have been usedwidely in non-coal mining and construction blasting andthe technology is well developed However owing to thecomplexity of the coal seam environment hydration reac-tions of expansive materials used in construction technologymay cause some stability issues thus their use requiresfurther optimization and this technology has not yet beenused in coal production

Although the pressure in the borehole will decreasewhen the coal body breaks as the hydration reaction con-tinues the volume of the expansive material can increase bymore than 2 times and the width and length of the cracksproduced by the coal seam will continue to develop -eexpansive pressure generated by the hydration reaction ofthe expansive material has a slower reaction speed and auniform pressure increase to cause the cracked object so thewhole crushing process is noise-free dust-free and vibra-tion-free After the hydration reaction it does not produceany toxic and harmful substances which is a safe and reliableway of fracturing -e main features of the expansivefracturing were compared with those of other methods asshown in Table 1

Traditional borehole drilling technology is one of themost common methods adopted for use in coal seams withlow gas permeability drilling in this manner has been shownto increase the exposed area and pressure release range ofboreholes thus both increasing gas drainage and reducinggas pressure Here a new technology that increases thepermeability of coal seams is proposed this method adoptsrecent advances in borehole technology and expansivematerials rather than relying on traditional methodsAccording to existing knowledge regarding borehole gasdrainage the expansion of boreholes in coal seams can beachieved using either perfusive materials or expansivematerials the nature of this expansion depends on the ex-pansive pressure exerted by drilling in the vicinity of coalfractures and on the physical and chemical changes thataffect the gas state -e ability to increase coal seam per-meability using these techniques could help address gasdrainage issues associated with mining processes -ereforethe production of an expansive material for use in coal seamswould be of great theoretical and practical significance forcoal mine production safety gas resource development andenvironmental protection

2 Materials and Methodology

21 Materials -e expansive materials were calcined attemperatures of 1350ndash1500degC and comprised primarily the

following components (in order of decreasing percentagecontent) calcium oxide (f-CaO) tricalcium silicate (C3S)tetracalcium aluminoferrite (C4AF) and tricalcium alumi-nate (C3A) Based on mass balance calculations calciumoxide reacts with silicon dioxide (SiO2) aluminum oxide(Al2O3) and ferric oxide (Fe2O3) producing tricalciumsilicate (C3S) tetracalcium aluminoferrite (C4AF) and tri-calcium aluminate (C3A) and transforms the remainingcalcium oxide to f-CaO -e components of the expansivematerials are presented in Table 2

22 Reaction Temperature Measurement Owing to thecomplexity of the coal seam environment and to ensureproduction safety accurate reaction parameters must berecorded for expansive materials used in coal seams Inparticular reaction temperature and reaction rate are im-portant factors determining the effects of expansivematerials

-e use of expansive materials in coal seam drilling toinduce expansive fracturing can result in exothermichydration reactions and increase the volume of calciumoxide (CaO) [11 14 15] magnesium oxide (MgO) andanhydrous calcium sulfoaluminate (3CaOmiddotAl2O3)[16 17] -e main hydration reactions for the expansivematerial are as follows

CaO + H20⟶ Ca(OH)2 + Huarr

MgO + H20⟶ Mg(OH)2 + Huarr

3CaO middot Al2O3 + 3CaSO4 + 32H20⟶ 3CaO middot Al2O3 middot 3CaSO4 middot 32H2 0 + Huarr

(1)

Physical parameters of each compound are shown in Ta-ble 3 Calcium oxide (CaO) reacts with water to producecalcium hydroxide (Ca (OH)2) Magnesium oxide (MgO) re-acts with water to produce magnesium hydroxide (Mg (OH)2)calcium sulfate (CaSO4) and anhydrous calcium sulfoalumi-nate (3CaOmiddotAl2O3) react with water to produce calcium sul-foaluminate hydrates (3CaOmiddotAl2O3middot3CaSO4middot32H2O) -e solidvolume growth rate after hydration is as follows [13]

ΔVCaO 3318 minus 1679

1679times 100 97

ΔVMgO 2471 minus 1126

1126times 100 119

ΔVCA 725 minus 371

371times 100 95

(2)

-e device used to test reaction temperature is shown inFigure 1 Temperature tests were conducted under ambienttemperature conditions (sim20degC) A sealing and heat pres-ervation device (volume 1 L) was adopted a Pt100 tem-perature sensor (measurement range 0ndash200degC) wasconnected and the MK-200E paperless recorder was used tomonitor data A balance (accurate to 001 g) was used toweigh out 500 g of the expansive material then the materialwas stirred evenly with varying proportions of water beforebeing added to the insulation device Changes in reactiontemperature over time were recorded

2 Shock and Vibration

23 Expansive Pressure Measurement -e measurement ofexpansion pressure is made using thick-walled roundsteel tubes based on Building Materials Industry Standardof China (JC 506-1992) -e basic principles underlyingexpansive pressure testing of expansive materials are asfollows -e expansive material is poured into a thick-walled circular steel tube when the expansive material inthe tube undergoes a hydration reaction and expands involume [18] the material will exert strain on the tubewall -is causes the tube to expand -e expansivepressure acting on the inner wall of the tube can bedescribed by the thick-wall cylinder theory of elasticmechanics [19 20] -e radial compressive stress andtangential tensile stress of the thick-walled tube underexpansive pressure are as follows

σr Pex minus P0( 1113857R2

i

R2e minus R2

i

1 minusR2

e

r21113890 1113891 (3)

σθ Pex minus P0( 1113857R2

i

R2e minus R2

i

1 +R2

e

r21113890 1113891 (4)

where σr and σθ are the radial compressive stress andtangential tensile stress respectively and Pex and P0 are theinternal expansive and external pressures respectivelyUnder the test conditions considered here the steel tube isnot subject to external pressures such that P0 0 Ri and Rerepresent the internal radius and external radius respec-tively and r is the radial distance from the center to thecylinder When rRe equations (3) and (4) can be modifiedas follows

σθ 2PexR

2i

R2e minus R2

i

(5)

According to the theory of elasticity the tangential strainof a steel tube under radial and tangential stress is as follows

εθ σθ minus υσr

E

2PexR2i

E R2e minus R2

i( 1113857 (6)

where E is the elastic modulus of the steel tube -en theexpansive pressure can be expressed as follows

Table 1 Comparison of expansive fracturing with other methods of permeability improvement

Method Principle Advantage LimitationExpansivefracturing

Solid expansion andexothermic desorption

Noise-free dust-free andvibration-free Reaction exotherm

Concussionblasting Gas volume expansion Quick reaction and

obvious effectVibration noise flying stone toxic gas and easy to induce

gas outburst

Drilling Pressurization-discharging Traditional technology Large amount of work long construction period and rapiddrilling-induced coal and gas outburst

Hydraulic methodLiquid punchingfracturing anddisplacement

-e coal is adequatelyrelieved of pressure

Fracture development has no direction and the process iscomplex

CO2 phase changefracturing

Gas volume expansion anddisplacement

Gas can be replaced toimprove the recovery rate

-e coal body with complex device high sealingrequirement of borehole and excessive crushing is easy to

lead to pore blockage

Table 2 Components of expansive materials

Chemical composition ()Liter weight (gL)

LOI (loss on ignition) SiO2 Al2O3 Fe2O3 CaO MgO f-CaO 1113936

062 541 110 260 8910 092 7326 9975 1320

Table 3 Physical parameters of each compound

CaO MgO CaOmiddotAl2O3 CaSO4 Ca (OH)2 Mg (OH)2 H2OMolecular weight (g) 5608 4030 10196 17217 7408 5832 1802Apparent density (gcm3) 334 358 390 261 224 236 100Gram-molecular volume (cm3) 1679 1126 2614 6597 3308 2471 1802

Figure 1 Device used to test reaction temperature

Shock and Vibration 3

Pex εθE R2

e minus R2i( 1113857

2R2i

(7)

In this test a Q235 cold-processed steel tube was usedwith an elastic modulus of 20006GPa and an inner radiusouter radius and length of 20mm 24mm and 500mmrespectively [21] One end of the steel tube was sealed bywelding with a thick steel plate -e resistance strain gaugewas glued to the adhesive strain gauge at the midpoint of thesteel tube 250mm from the base of the tube -e straingauge used was model BX120-20AA -e leading end of the

resistance strain gauge was connected to the strain gauge bya double-stranded wire [21 22] and the steel tube was placedin a water bath with a constant temperature of 25degC -edevice used to test expansive pressure is shown in Figure 2

24 Microstructural Analysis of Expansive Material UsingSEM To further analyze the expansive pressure generatedby the expansive material and investigate the structuralchanges and mechanical properties of the material its mi-crostructure before and after the hydration reaction was

Expansion steel tube

Expansion material Strain gauge and data acquisition

Constant temperature water tank

Strain gauge

Watersurface

500m

m

250m

m

oslash48mmoslash40mm

Figure 2 Determination of expansive pressure

Uniaxial pressure system

Similar materials

Expansion borehole

Expansionborehole

Fixed restraint device

VIC-3D contactlessfull-field strain

measurement system

σ2 σy

σx

σz

σx

Figure 3 Experimental setup used to analyze fracturing of the expansive material


studied using the JSM-IT100 scanning electron microscope(SEM) [23 24] Double-sided tape was pasted on the loadtray to maintain a dry environment and small samples of theexpansive material were placed on the tape to ensure uni-form distribution Metal film was sprayed on the surface ofthe sample before the microstructural morphology of theexpansivematerial was observed-e hydration reaction wasinduced by adding +30 water for 24 h then a specimen ofthe expansive material was observed to identify any changesin crystal structure following hydration

25 Fracture Analysis of Expansive Material

251 Preparation of Coal-Like Materials -e compressivestrengths of materials can be used as an index to measuretheir similarity to raw coal Cement and gypsum were usedto produce amaterial with similar strength to coal-e ratiosof pulverized coal to cement gypsum and water in thismaterial were determined to be 05 025 005 02 based onthe results of uniaxial testing undertaken in previous studies[25] -is mixture was stirred evenly and placed into a self-made cube mold with dimensions of 200times 200times 200mmthe mold was left to stand for 9-10 h to allow demodulationand was maintained at constant temperature in a dryingoven for one week -en the center of the coal-like materialwas drilled using a coring drill with diameter of 20mm

252 VIC-3D System for Strain Measurement -e surfacedisplacement and strain distribution of the coal-like materialunder expansive pressure and uniaxial stress were calculatedby comparing image correlation points with the VIC-3Dcontactless full-field strainmeasurement system-is systemrequires only two image collectors -e surface of the testedmaterial was coated with a random black and white patternDuring the deformation of the sample the movement ofindividual pixels was recorded and translated into a vectorin this manner the strain data before and after deformationcan be determined based on a vector field generated by thesurface deformation of the material -e coal-like materialand the experimental setup used to analyze fracturing of theexpansive material are shown in Figure 3 Coal seams areunder static isotropic pressure due to the overlying andsurrounding rocks and this pressure increases with depth ofa coal seam within the rock mass Here the distribution ofcoal seam stress was optimized by setting the boundaryconditions in the x minusx and minusy directions as fixed con-straints with the in situ stress σz 5MPa -e y directionindicates distance along the mining section with the y axisset as the free surface

3 Results and Discussion

31 Reaction Temperature Temperature is one of the pri-mary factors influencing the performance of the expansivematerial when temperature is higher the hydration rate ofthe expansive material is faster and the expansion pressureexerted is higher Moreover the response of expansivematerials with different proportions of water added for the

hydration reaction (25 30 and 35) will vary dependingon temperature Reaction temperatures were measuredduring the laboratory experiments as shown in Figure 4-eresults show that changes in reaction temperature can becontrolled effectively by controlling the water-cement ratio

Changes in reaction temperature for expansive materialswith different water-cement ratios can be summarized asfollows Initially reaction temperature increases slowly overthe range 20ndash40degC when the temperature reaches 40degC thereaction speeds up and there is a marked increase in tem-perature Subsequently reaction temperature peaks beforedeclining slowly-ese results demonstrate that temperaturechanges during the hydration reaction of the expansivematerial exhibit the same form regardless of water content-e maximum reaction temperatures reached for the +25

ndash20 0 20 40 60 80 100 120 140 1600

20

40

60

80

100

120

140

160

180

200

+25 water+30 water+35 water

Reac

tion

tem

pera

ture

(degC)

Time (min)

Figure 4 Variation in reaction temperature with time

0 40 80 120 160 200

0

2

4

6

8

10

12

14

16

Temperature (degC)

Hea

ting

rate

K (deg

Cmiddotm

inndash1

)


Figure 5 Heating rate curve for the expansive material


+30 and +35 mixtures were 190degC 100degC and 126degCrespectively these temperatures were reached at 55 60 and65min respectively -ese results demonstrate that the timerequired for the expansive material to reach the maximumreaction temperature increases with increasing water-ce-ment ratio However the maximum reaction temperaturewas found to decrease considerably with increasing watercontent between +25 and +35

-e temperature of the expansive material was measuredevery 5min for each mixture and the temperature depen-dence of the heating rate K was investigated -is parameteris considered to represent the rate of change of reactiontemperature for the expansive material where KΔT5

-e heating rate curve for the expansive material with+25 +30 and +35 water is presented in Figure 5 thiscurve was developed based on fitting of the temperature

SED 200kV WD12mmPC50 times2500 10μmHV

(a)

SED 200kV WD12mmPC50 times10000HV 1μm

(b)

SED 200kV WD11mmPC50 10μmHV times2500

(c)


(d)

Figure 7 SEM images for expansive material (a) Sample before hydration at 2500x (b) Sample before hydration at 10000x (c) Sampleafter hydration at 2500x (d) Sample after hydration at 10000x

0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)

Pex = 5754979 ndash 4970821lowast094998h

ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417

Figure 6 Changes in tangential strain for steel tube and expansive pressure of expansive material over time


change curve in Figure 4 -ese results demonstrate thatwhen the reaction temperature of the expansive material isless than 40degC the heating rate is slow and is effectively the

same for all three types of expansive material Converselywhen the reaction temperature exceeds 40degC the heatingrate increases rapidly for all three types although heating

eyy [1]-Lagrange

000435000379688000324375000269062000213750001584380001031250000478125ndash749999e-05ndash0000628125ndash000118125ndash000173437ndash00022875ndash000284062ndash000339375ndash000394687ndash00045

exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625

ndash562503e-05ndash00005625ndash000106875ndash0001575ndash000208125ndash00025875ndash000309375ndash00036

000045

0048004415620040312500364688003262500287813

0021093700172500134062000956250005718750001875ndash000196875ndash00058125ndash000965625ndash000135

00249375

eyy [1]-Lagrange

exx [1]-Lagrange

006600604687005493750049406300438750038343700328125002728130021750016218700106875000515625ndash0000375001ndash000590625ndash00114375ndash00169688ndash00225

eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005

Figure 8 Variation in strain response for coal-like materials with reaction time similar to the expansive material considered here (a)-1Hydration reaction time 3 h (x direction strain) (a)-2 Hydration reaction time 3 h (y direction strain) (b)-1 Hydration reaction time 6 h (xdirection strain) (b)-2 Hydration reaction time 6 h (y direction strain) (c)-1 Hydration reaction time 10 h (x direction strain) (c)-2Hydration reaction time 10 h (y direction strain)


occurs much more rapidly for the material with +30 and+35 water than for the material with +25 water -isoccurs because the heat of hydration reactions is releasedmore rapidly with increasing moisture content morecomplete reaction of the expansive material also occurs withincreasing moisture content However when the moisturecontent is very high and the reaction temperature reaches100degC (ie the boiling point of water) the water begins toevaporate resulting in a reduction in the rate of heatingConversely when the moisture content is low the influenceof water on the expansive material leads to a continuousincrease in the heating rate Here the maximum tempera-ture reached for the expansive material with +30 water was100degC accordingly it can be assumed that complete hy-dration of the expansive material occurred and that themoisture content effectively controlled the reactiontemperature

32 Expansive Pressure Measurement of the expansivepressure of the expansive material based on tangentialstrain exerted on a thick-walled circular steel tube ispresented here -rough the test of variation in reactiontemperature with time it is determined that the expansivematerial under the condition of +30 water is mostsuitable for coal seam so only the expansive pressureunder this specific condition is measured Changes intangential strain and expansive pressure with time areillustrated in Figure 6

-e test was conducted in a water bath with a constanttemperature of 25degC Initially the reaction rate of theexpansive material was rapid this accelerated reactionincreased the tangential strain significantly As the testprogressed the reaction slowed down gradually resultingin small changes in strain However as the expansivematerial was not fully developed when the reaction rateslowed the tangential strain continued to increase slowlyAccordingly the measured strain did not reach a stablelevel until sim120 h after the reaction was initiated As thestrain gauge used here is relatively sensitive variation instrain with time (h) was further analyzed and fittedaccording to the following relationship

εθ 130755743 minus 11293933 times 094998h (8)

-e expansive pressure can be obtained based on thestrain acting on the steel tube as described in equation (4) Asshown in Figure 6 comparative analysis has shown thatexpansive pressure varies with time in a manner similar tostrain in fact the expansive pressure of the expansivematerial increases with time to a maximum of 57MPa-eseresults suggest that the expansive pressure generated by thehydration reaction of the expansive material can be utilizedto fracture coal seams by drilling

33 Microstructural Analysis Using SEM SEM micrographsof the expansive material before and after hydration areshown in Figure 7 and demonstrate clearly that hydrationchanges the microstructure and density of the expansive

material As shown in Figures 7(a) and 7(b) the expansivematerial was composed of particles with smooth dense andnonporous surfaces before hydration the apparent densityof these particles was relatively high-emain component ofthe expansive material is calcium oxide Small and dispersedparticles of calcium oxide facilitate hydration formingcalcium hydroxide crystal centers and a large number of finecrystals As shown in Figures 7(c) and 7(d) the particlesurfaces following hydration are relatively rough andmicrocracks and nanocracks are relatively well dispersedforming many small voids and increasing porosity althoughthe volume of the hydrated particles is twice that of theoriginal particles -ese results demonstrate that changes inexpansive pressure are a result of changes in crystal structureduring hydration

34 Analysis of Borehole Expansive Fracturing Images takenby the VIC-3D contactless full-field strain measurementsystem can be used to explain the development of strain overtime when expansive materials are used to fracture coal-likematerials Changes in the expansive pressure occur withincreasing hydration time this is reflected in changes in themechanical properties of the expansive material Changes instrain response for the materials with similar reaction timesto the expansive material used here are shown in Figure 8

In Figure 8 high-strain regions are shown in red andlow-strain regions are shown in blue For the coal-likematerials it is clear that under uniaxial stress the failuremechanism develops fromwidely distributed strain to highlylocalized strain with increasing hydration time -e widerdistribution of strain results partly from the expansivepressure of the material after hydration and partly from theaction of in situ stress -e figure also shows the fracturecharacteristics of the coal-like materials with fixed con-straints these conditions replicate the crushing mechanismthat acts during the fracture process as a result of holes beingdrilled in the surrounding area during the reaction of ex-pansive materials With increasing hydration reaction timethe fracture effect is gradually increased Fitting analysis wasperformed on the maximum stress variables at differenttimes in the x and y directions the results are presented in

0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244

Figure 9 Variation in maximum stress variables with time in the xand y directions


Figure 9-e strain was found to increase significantly after areaction time of 6 h indicating that the coal-like materialfractured this can be considered to represent the formationof a gas migration channel in a coal seam

Further analysis was conducted for the coal-like mate-rials in the form of a displacement test (Figure 10) -enumber of macroscopic cracks on the surface of the coal-likematerial increased to 4 and cracks started to form in the

V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625

ndash000312498ndash01025ndash0201875ndash030125ndash0400625ndash05

009625

U (mm)109

ndash021

V (mm)09550882187080937507365620663750590937051812504453120372502996880226875015406200812500084375ndash0064375ndash0137187ndash021

U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007

Figure 10 Variation in displacement of coal-like materials with reaction time of the expansive material (a)-1 Hydration reaction time 3 h (xdirection displacement) (a)-2 Hydration reaction time 3 h (y direction displacement) (b)-1 Hydration reaction time 6 h (x directiondisplacement) (b)-2 Hydration reaction time 6 h (y direction displacement) (c)-1 Hydration reaction time 10 h (x direction displacement)(c)-2 Hydration reaction time 10 h (y direction displacement)


outer wall of the expansion borehole and penetrate the entirespecimen In the expansive material thermal stress was thedominant controlling factor at the start of the reactionforming a temperature gradient around the borehole thiscontributed to changes in the physical and mechanicalproperties of material in this area In particular elevatedtemperature resulted in thermal expansion and increases inin situ stress focusing stress along the coal specimenboundary and forming fractures in the damaged area As thereaction progressed the expansive stress became thedominant controlling factor Meanwhile the constraintimposed by the borehole wall of the coal specimen washigher than that of the boundary Under the action of theexpansive force cracks began to form in the damaged stripalong the boundary and these cracks expanded from theborehole to the boundary until the coal-like materials wereconnected Changes in fracture displacement with time areshown in Figure 11 Four main cracks were generated duringthe test the length and width of these cracks increased withthe reaction time of the expansive material

4 Conclusion

Based on a combination of theoretical research basic testingand fracture testing the response characteristics of an ex-pansive material and its effect on fracturing of coal-likematerials have been studied -e following conclusions canbe drawn

Measurement of the basic parameters of the expansivematerial indicated that the hydration temperature of theexpansive material was lowest (100degC) when +30 water wasused After the expansive material had reacted fully itcontinued to exert pressure on the wall of the steel tubecontrolling the expansive pressure effectively at 57MPa

Based on investigation of the mechanical properties andstructural characteristics of coal expansive fracture testingwas conducted on materials with reaction times similar tothat of the expansive material Four main cracks weregenerated by fracturing of the test block

Coal seam fracturing based on expansive materials isknown to be safe easy to undertake low in cost noise-free

dust-free vibration-free and free from toxic gas products-is study represents an initial feasibility study for thepractical application of this technology -e process of ex-pansion is known to increase damage and exploit inherentweaknesses in coal seams However the slow development offractures can ensure stability of the coal roof effectivelypreventing coal and gas outburst and may be suitable forapplication in gas prevention and control for low-perme-ability coal seams Such application could greatly reduceconstruction quantity and operation time Application ofthis new coal seam fracturing technology based on expansivematerials may prove to be feasible in practice and meritsfurther investigation

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-is research was supported by the National Natural ScienceFoundation Fund (51874012) the National Key Researchand Development Plan (2018YFC0808100) the HebeiNatural Science Foundation Fund (E2016209249) and theGraduate Student Innovation Fund of North China Uni-versity of Science Technology (2018B26)

References

[1] W Yang B-q Lin Y-a Qu et al ldquoStress evolution with timeand space during mining of a coal seamrdquo InternationalJournal of Rock Mechanics and Mining Sciences vol 48 no 7pp 1145ndash1152 2011

[2] Y-P Cheng L Wang and X-L Zhang ldquoEnvironmentalimpact of coal mine methane emissions and respondingstrategies in Chinardquo International Journal of Greenhouse GasControl vol 5 no 1 pp 157ndash166 2011

[3] H Zhou J Gao K Han and Y Cheng ldquoPermeability en-hancements of borehole outburst cavitation in outburst-pronecoal seamsrdquo International Journal of Rock Mechanics andMining Sciences vol 111 pp 12ndash20 2018

[4] D Li ldquoA new technology for the drilling of long boreholes forgas drainage in a soft coal seamrdquo Journal of Petroleum Scienceand Engineering vol 137 pp 107ndash112 2016

[5] E C Dunlop A Salmachi and P J McCabe ldquoInvestigation ofincreasing hydraulic fracture conductivity within producingultra-deep coal seams using time-lapse rate transient analysisa long-term pilot experiment in the Cooper Basin AustraliardquoInternational Journal of Coal Geology vol 103 2019

[6] Y Lu LWang Z Ge Z Zhou K Deng and S Zuo ldquoFractureand pore structure dynamic evolution of coals during hy-draulic fracturingrdquo Fuel vol 259 p 116272 2020

[7] J Xu C Zhai L Qin and G Yu ldquoEvaluation research of thefracturing capacity of non-explosive expansion material ap-plied to coal-seam roof rockrdquo International Journal of RockMechanics and Mining Sciences vol 94 pp 103ndash111 2017

00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10

Figure 11 Changes in maximum displacement with time in the xand y directions


[8] C Zhai J Xu S Liu and L Qin ldquoFracturing mechanism ofcoal-like rock specimens under the effect of non-explosiveexpansionrdquo International Journal of Rock Mechanics andMining Sciences vol 103 pp 145ndash154 2018

[9] W Nocun-Wczelik Z Konik and A Stok ldquoBlended systemswith calcium aluminate and calcium sulphate expansive ad-ditivesrdquo Construction and Building Materials vol 25 no 2pp 939ndash943 011

[10] X Li Y Zhang X Shen Q Wang and Z Pan ldquoKinetics ofcalcium sulfoaluminate formation from tricalcium aluminatecalcium sulfate and calcium oxiderdquo Cement and ConcreteResearch vol 55 pp 79ndash87 2014

[11] K Goto K Kojima and K Watabe ldquo-e mechanism ofexpansive pressure and blowout of static demolition agentrdquo inProceedings of the Paper Presented at the Second InternationalRILEM Symposium on Demolition and Reuse of Concrete andMasonry Tokyo Japan November 1988

[12] X Liu B Ma H Tan et al ldquoEffect of aluminum sulfate on thehydration of Portland cement tricalcium silicate and trical-cium aluminaterdquo Construction and Building Materialsvol 232 p 117179 2020

[13] B You Static Blasting Technology Silent Crushing Agent andits Application China Building Materials Industry PressTaiyuan China 2008

[14] S Arshadnejad K Goshtasbi and J Aghazadeh ldquoA model todetermine hole spacing in the rock fracture process by non-explosive expansion materialrdquo International Journal ofMinerals Metallurgy and Materials vol 18 no 5 pp 509ndash514 2011

[15] A S Natanzi D F Laefer and L Connolly ldquoCold andmoderate ambient temperatures effects on expansive pressuredevelopment in soundless chemical demolition agentsrdquoConstruction and Building Materials vol 110 pp 117ndash1272016

[16] W Nocun-Wczelik A Stok and Z Konik ldquoHeat evolution inhydrating expansive cement systemsrdquo Journal of ermalAnalysis and Calorimetry vol 101 pp 527ndash532 2010

[17] S Arshadnejad ldquoDesign of hole pattern in static rock fractureprocess due to expansion pressurerdquo International Journal ofRockMechanics andMining Sciences vol 123 p 104100 2019

[18] V R S De Silva P G Ranjith M S A Perera B Wu andT D Rathnaweera ldquoInvestigation of the mechanical mi-crostructural and mineralogical morphology of soundlesscracking demolition agents during the hydration processrdquoMaterials Characterization vol 130 pp 9ndash24 2017

[19] S P Timoshenko and J N Goodier eory of ElasticityMcGraw Book Company New York NY USA 1951

[20] A Bentur and M Ish-Shalom ldquoProperties of type K expensivecement of pure components II Proposed mechanism ofettringite formation and expansion in unrestrained paste ofpure expansive componentrdquo Cement and Concrete Researchvol 4 no 5 pp 709ndash721 1974

[21] R W Hertzberg Deformation and Fracture Mechanics ofEngineering Materials John Wiley amp Sons New York NYUSA 1996

[22] J Hinze and J Brown ldquoProperties of soundless chemicaldemolition agentsrdquo Journal of Construction Engineering andManagement vol 120 no 4 pp 816ndash827 1994

[23] B Kwiecinska S Pusz J Brett and Valentine ldquoApplicationof electron microscopy TEM and SEM for analysis of coalsorganic-rich shales and carbonaceous matterrdquo InternationalJournal of Coal Geology vol 211 pp 103ndash203 2019

[24] S-B Song J-F Liu D-S Yang et al ldquoPore structurecharacterization and permeability prediction of coal samples

based on SEM imagesrdquo Journal of Natural Gas Science andEngineering vol 67 pp 160ndash171 2019

[25] W Zhang Influence of Borehole Expansion Agent on Devel-opment Law of Coal Seam Fissure North China University ofScience and Technology Habei China 2019


1950s Early efforts investigated the sintering of high-alu-minum cement with a rotary kiln and provided importantguidance for future investigation of expansive materials [12]while a self-stressing silicate cement was developed suc-cessfully in 1957 A later study investigated the viability ofusing calcium oxide calcined at high temperature as anexpansive source based on analysis of the reaction mech-anisms of the expansive material and on laboratory ex-periments and industrial testing and developed anexpansive crushing agent with a reaction pressure that canexceed 60MPa [13] Expansive materials have been usedwidely in non-coal mining and construction blasting andthe technology is well developed However owing to thecomplexity of the coal seam environment hydration reac-tions of expansive materials used in construction technologymay cause some stability issues thus their use requiresfurther optimization and this technology has not yet beenused in coal production

Although the pressure in the borehole will decreasewhen the coal body breaks as the hydration reaction con-tinues the volume of the expansive material can increase bymore than 2 times and the width and length of the cracksproduced by the coal seam will continue to develop -eexpansive pressure generated by the hydration reaction ofthe expansive material has a slower reaction speed and auniform pressure increase to cause the cracked object so thewhole crushing process is noise-free dust-free and vibra-tion-free After the hydration reaction it does not produceany toxic and harmful substances which is a safe and reliableway of fracturing -e main features of the expansivefracturing were compared with those of other methods asshown in Table 1

Traditional borehole drilling technology is one of themost common methods adopted for use in coal seams withlow gas permeability drilling in this manner has been shownto increase the exposed area and pressure release range ofboreholes thus both increasing gas drainage and reducinggas pressure Here a new technology that increases thepermeability of coal seams is proposed this method adoptsrecent advances in borehole technology and expansivematerials rather than relying on traditional methodsAccording to existing knowledge regarding borehole gasdrainage the expansion of boreholes in coal seams can beachieved using either perfusive materials or expansivematerials the nature of this expansion depends on the ex-pansive pressure exerted by drilling in the vicinity of coalfractures and on the physical and chemical changes thataffect the gas state -e ability to increase coal seam per-meability using these techniques could help address gasdrainage issues associated with mining processes -ereforethe production of an expansive material for use in coal seamswould be of great theoretical and practical significance forcoal mine production safety gas resource development andenvironmental protection

2 Materials and Methodology

21 Materials -e expansive materials were calcined attemperatures of 1350ndash1500degC and comprised primarily the

following components (in order of decreasing percentagecontent) calcium oxide (f-CaO) tricalcium silicate (C3S)tetracalcium aluminoferrite (C4AF) and tricalcium alumi-nate (C3A) Based on mass balance calculations calciumoxide reacts with silicon dioxide (SiO2) aluminum oxide(Al2O3) and ferric oxide (Fe2O3) producing tricalciumsilicate (C3S) tetracalcium aluminoferrite (C4AF) and tri-calcium aluminate (C3A) and transforms the remainingcalcium oxide to f-CaO -e components of the expansivematerials are presented in Table 2

22 Reaction Temperature Measurement Owing to thecomplexity of the coal seam environment and to ensureproduction safety accurate reaction parameters must berecorded for expansive materials used in coal seams Inparticular reaction temperature and reaction rate are im-portant factors determining the effects of expansivematerials

-e use of expansive materials in coal seam drilling toinduce expansive fracturing can result in exothermichydration reactions and increase the volume of calciumoxide (CaO) [11 14 15] magnesium oxide (MgO) andanhydrous calcium sulfoaluminate (3CaOmiddotAl2O3)[16 17] -e main hydration reactions for the expansivematerial are as follows

CaO + H20⟶ Ca(OH)2 + Huarr

MgO + H20⟶ Mg(OH)2 + Huarr

3CaO middot Al2O3 + 3CaSO4 + 32H20⟶ 3CaO middot Al2O3 middot 3CaSO4 middot 32H2 0 + Huarr

(1)

Physical parameters of each compound are shown in Ta-ble 3 Calcium oxide (CaO) reacts with water to producecalcium hydroxide (Ca (OH)2) Magnesium oxide (MgO) re-acts with water to produce magnesium hydroxide (Mg (OH)2)calcium sulfate (CaSO4) and anhydrous calcium sulfoalumi-nate (3CaOmiddotAl2O3) react with water to produce calcium sul-foaluminate hydrates (3CaOmiddotAl2O3middot3CaSO4middot32H2O) -e solidvolume growth rate after hydration is as follows [13]

ΔVCaO 3318 minus 1679

1679times 100 97

ΔVMgO 2471 minus 1126

1126times 100 119

ΔVCA 725 minus 371

371times 100 95

(2)

-e device used to test reaction temperature is shown inFigure 1 Temperature tests were conducted under ambienttemperature conditions (sim20degC) A sealing and heat pres-ervation device (volume 1 L) was adopted a Pt100 tem-perature sensor (measurement range 0ndash200degC) wasconnected and the MK-200E paperless recorder was used tomonitor data A balance (accurate to 001 g) was used toweigh out 500 g of the expansive material then the materialwas stirred evenly with varying proportions of water beforebeing added to the insulation device Changes in reactiontemperature over time were recorded




i

R2e minus R2

i

1 minusR2

e

r21113890 1113891 (3)


i

R2e minus R2

i

1 +R2

e

r21113890 1113891 (4)


σθ 2PexR

2i

R2e minus R2

i

(5)



E

2PexR2i

E R2e minus R2

i( 1113857 (6)








gas outburst













062 541 110 260 8910 092 7326 9975 1320





Pex εθE R2


2R2i

(7)







Strain gauge

Watersurface

500m

m

250m

m




Similar materials

Expansion borehole

Expansionborehole



measurement system

σ2 σy

σx

σz

σx











ndash20 0 20 40 60 80 100 120 140 1600

20

40

60

80

100

120

140

160

180

200


Reac

tion

tem

pera

ture

(degC)

Time (min)


0 40 80 120 160 200

0

2

4

6

8

10

12

14

16

Temperature (degC)

Hea

ting

rate

K (deg

Cmiddotm

inndash1

)








(a)


(b)


(c)


(d)


0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)


ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417





eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10

























i

R2e minus R2

i

1 minusR2

e

r21113890 1113891 (3)


i

R2e minus R2

i

1 +R2

e

r21113890 1113891 (4)


σθ 2PexR

2i

R2e minus R2

i

(5)



E

2PexR2i

E R2e minus R2

i( 1113857 (6)








gas outburst













062 541 110 260 8910 092 7326 9975 1320





Pex εθE R2


2R2i

(7)







Strain gauge

Watersurface

500m

m

250m

m




Similar materials

Expansion borehole

Expansionborehole



measurement system

σ2 σy

σx

σz

σx











ndash20 0 20 40 60 80 100 120 140 1600

20

40

60

80

100

120

140

160

180

200


Reac

tion

tem

pera

ture

(degC)

Time (min)


0 40 80 120 160 200

0

2

4

6

8

10

12

14

16

Temperature (degC)

Hea

ting

rate

K (deg

Cmiddotm

inndash1

)








(a)


(b)


(c)


(d)


0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)


ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417





eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10























Pex εθE R2


2R2i

(7)







Strain gauge

Watersurface

500m

m

250m

m




Similar materials

Expansion borehole

Expansionborehole



measurement system

σ2 σy

σx

σz

σx











ndash20 0 20 40 60 80 100 120 140 1600

20

40

60

80

100

120

140

160

180

200


Reac

tion

tem

pera

ture

(degC)

Time (min)


0 40 80 120 160 200

0

2

4

6

8

10

12

14

16

Temperature (degC)

Hea

ting

rate

K (deg

Cmiddotm

inndash1

)








(a)


(b)


(c)


(d)


0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)


ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417





eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10































ndash20 0 20 40 60 80 100 120 140 1600

20

40

60

80

100

120

140

160

180

200


Reac

tion

tem

pera

ture

(degC)

Time (min)


0 40 80 120 160 200

0

2

4

6

8

10

12

14

16

Temperature (degC)

Hea

ting

rate

K (deg

Cmiddotm

inndash1

)








(a)


(b)


(c)


(d)


0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)


ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417





eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10



























(a)


(b)


(c)


(d)


0

10

20

200

30

40

40

50

60

60 80 100 120

0 20 40 60 80 100 120

0

300

600

900

1200

1500

Expa

nsiv

e pre

ssur

e (M

Pa)

Time (h)


ε θ1

0ndash6

Time (h)

εθ = 130755743 ndash 11293933lowast094998h

R2 = 093417





eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10

























eyy [1]-Lagrange


exx [1]-Lagrange

0004500039937500034875000298125000247500019687500014625000095625


000045

0048004415620040312500364688003262500287813


00249375

eyy [1]-Lagrange

exx [1]-Lagrange


eyy [1]-Lagrange

00760070906200658125006071870055625005053120045437500403437003525003015620025062500199687001487500097812500046875ndash000040625ndash00055

exx [1]-Lagrange

0091008500790073006700610055004900430037003100250019001300070001ndash0005






εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10


























εθ 130755743 minus 11293933 times 094998h (8)






0 2 4 6 8 10

00

02

04

06

08

10 020

015

010

005

000

ε x

Time (h)

εx = 142696endash9h883219

R2 = 099583

ε y

εy = 599183endash5h348279

R2 = 096244





V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10

























V (mm)0162501585015450150501465014250138501345013050126501225011850114501105010650102500985

U (mm)0112501086250104750100875009700931250089250085375008150077625007375006987500660062125005825005437500505

V (mm)1514151331245116107509909050820735065056504803950310225014

09906250891250791875069250593125049375039437502950195625


009625

U (mm)109

ndash021


U (mm)122113937105875097812508975081687507362506556250575049437504137503331250252501718750091250010625ndash007




4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10
























4 Conclusion






Data Availability




Acknowledgments


References








00

05

10

15

y = 004651h132263

R2 = 095842

x = 004795h141216

R2 = 097009

00

05

10

15

y (m

m)

x (m

m)

Time (h)0 2 4 6 8 10























experimentalinvestigationoftheuseofexpansivematerialsto ... · 2020. 7. 31. · described by the...

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