Jamova 2 SI 1000 Ljubljana, Slovenia Jamova Ljubljana, Slovenija

Transcription

1 Univerza v Ljubljani Fakulteta za grabeništvo in geoezijo University of Ljubljana Faculty of Civil an Geoetic Engineering Jamova 2 1 Ljubljana, Slovenija Jamova 2 SI 1 Ljubljana, Slovenia DRUGG Digitalni repozitorij UL FGG DRUGG The Digital Repository Ta članek je avtorjeva zanja recenzirana različica, kot je bila sprejeta po opravljeni recenziji. Prosimo, a se pri navajanju sklicujete na bibliografske poatke, kot je naveeno: This version of the article is author's manuscript as accepte for publishing after the review process. When citing, please refer to the publisher's bibliographic information as follows: Trtnik, G., Turk, G., Kavčič, F. in Bokan Bosiljkov, V. 28. Possibilities of using the ultrasonic wave transmission metho to estimate initial setting time of cement paste. Cement an Concrete Research 38, 11: DOI: 1.116/j.cemconres

2 Possibilities of using the ultrasonic wave transmission metho to estimate initial setting time of cement paste Gregor Trtnik a,b, Goran Turk a, Franci Kavčič b, Violeta Bokan Bosiljkov a,* a University of Ljubljana, Faculty of Civil an Geoetic Engineering Jamova 2, SI-111 Ljubljana, Slovenia b IGMAT.., Builing Materials Institute, Polje 31c, Ljubljana, Slovenia Abstract In this paper, the applicability of the ultrasonic wave transmission metho to estimate the initial setting time of an arbitrary cement paste is iscusse. Ultrasonic pulse velocity measurements were fully automate an measure continuously. The Vicat Neele Test was use in orer to etermine the initial setting time of cement pastes. Different cement pastes were prepare in orer to check the influence of the water/cement ratio, type of cement, curing temperature, cement fineness, an some clinker compositions, on the relationship between the initial setting time an ultrasonic pulse velocity. It was foun that the initial setting time of an arbitrary cement paste can be estimate very accurately by the time the first inflection point appears on the ultrasonic pulse velocity curve. Moreover, it can be estimate quite accurately by the time the ultrasonic pulse velocity reaches a fixe value, close to the value of the ultrasonic pulse velocity in water. Keywors: Hyration (A); Cement paste (D); No category: Ultrasonic wave transmission, Initial setting time * Corresponing author. Phone: aress: violeta.bokan-bosiljkov@fgg.uni-lj.si 1

3 1. Introuction Many test methos which evaluate the change of properties of cement-base materials with time exist. These methos have ifferent ranges of applicable material properties. Therefore, they are applicable to ifferent time-ranges in the setting an harening processes of cement. With the Vicat Neele [1] an Proctor Penetration Resistance [2] tests, the setting an harening states of the materials in the early stages are investigate by means of the change in the materials' penetration resistance. Unfortunately, these proceures o not allow measuring of setting an harening processes continuously, or are not base on truly mechanical parameters of the test material. Avances in measurement an computer technologies in recent years have allowe the evelopment of many avance methos to monitor the setting an harening process of cement paste, such as impactecho methos, pulse-echo methos, ultrasonic pulse velocity methos, wave reflection methos, resonant frequency methos, acoustic emission methos, microwave asorption methos, techniques measuring the conuctivity an resistance of the material to be teste, an so on. Some of these are completely nonestructive in their nature, which is another avantage of these methos over classical stanar methos, mentione above. Numerous attempts have been mae uring the last few years to etermine some properties of harening cement-base materials with ifferent ultrasonic methos. Valič [3] presente a new apparatus, metho, an some application examples for monitoring the hyration process of cementitious materials, by the pulse echo ultrasonic wave reflection metho. Reinhart et al. [4, ] evaluate changes in the material properties associate with concrete aging by using the velocity of elastic waves, energy, an frequency istribution of obtaine waves. The ultrasonic wave transmission metho was use in these stuies. A comparison between ultrasonic wave transmission an reflection measurements, using primary waves (P - waves) an seconary waves (S- waves) on mortar an concrete, in the early stages, was mae by Voight et al. [6]. Kamaa et al. [7] presente the relationship between ultrasonic propagation characteristics an some properties of harening cement paste an Krauss an Hariri [8] presente a proceure to etermine the en of the ormant phase an initial egree of hyration by measuring the ultrasonic pulse velocities of compression an shear waves for arbitrary concrete compositions. Also, numerous attempts were mae to 2

4 investigate the microstructure of cement-base materials by ultrasonic shear waves an numerical simulation [9, 1, 11] an some other properties of fresh cement-base materials [12, 13]. Researchers have also suggeste some methos base on ultrasonic wave transmission measurements for ientifying characteristic times in the hyration of cement. Accoring to Chotar et al. [14], important transition points in the ultrasonic pulse velocity (UPV) curve can be etermine at the intersections of three straight lines tangent to the curve. In some other stuies it was shown that the maximum of the first erivative of the UPV curves is a practical means to etermine the initial setting of mortars an concretes [4,, 6], while the final setting cannot clearly be associate with typical curve values, but it was suggeste to choose the time when a velocity value of 1 m/s on the concrete's UPV curve is exceee. Accoring to Lee et al. [1], certain ranges of ultrasonic pulse velocity values () with reasonable withs were suggeste for the initial setting times: i.e., 8-9 m/s an m/s for the initial setting of orinary Portlan cement concrete an high-performance concrete, respectively. The objective of this stuy was to investigate the relationship between the initial setting time (IST) of cement paste an ultrasonic propagation characteristics. Therefore, a comprehensive experimental work was performe in which the ultrasonic wave transmission metho was use. The influence of the water/cement (w/c) ratio, environmental temperature (T), type of cement (CT), cement fineness (BS), an amount of C 3 A (AC3A) on the initial setting time of cement paste, etermine from UPV curves an Vicat Neele tests, was stuie. 2. Experimental methos 2.1 Wave transmission metho The Proceq CCT4 set up was chosen as the founation an was aequately augmente to measure the automatically at any esire intervals after casting. This fully automate etermination of the initial onset of the signal is of special significance to routine inustrial application. The apparatus was connecte to the PC computer an special software was prepare in orer to collect ata with time. The travel time of the ultrasonic pulse t p (μs) through the sample is measure an the (km/s) is calculate as follows: 3

5 L = (1) t p where L (mm) is the length of the straight-wave-path through the specimen (i.e. 7 mm in this stuy). Cubic specimens of the size of mm 3 were use in the stuy. The apparatus consists of a waveform generator boar an two broaban transucers of central frequency 4 khz an 2 mm in iameter. With regars to the apparatus technology, one of the focal tasks has been the evelopment of an easily manageable container. After several tests, it was ecie to make the container of the extrue polystyrene foam Styrour. It is important to mention that no waves propagating through the container wall were etecte by the evice because of the high issipation of the Styrour material. This is of significant importance, specifically for carrying out measurements on very fresh cement-base materials. The sensors were partly pushe into the specimens (about mm) in orer to ensure goo contact between transucers an specimen an the acoustic coupling was enhance by a layer of roller bearing grease, which has been foun more appropriate than other commercial ultrasonic couplings. The measurements starte immeiately after casting an continue for 36 hours. The results were recore at one minute intervals in orer to capture all important trens of the UPV evelopment. 2.2 Vicat test of penetration resistance To evaluate the progress of the hyration reaction of the investigate materials, Vicat Neele tests (VNT) accoring to [1] were conucte. The metho is base on measuring a epth of penetration of a steel right cyliner neele into the cement paste. The time between starting time an the time at which the istance between the neele an the base plate is = 6 ± 3 mm, measure to the nearest minute, is efine as the initial setting time (IST) of the cement. Within this stuy, penetration tests were performe at regular time intervals until the cement paste was completely set. 4

6 3. Experimental program 3.1 Materials Twelve cement pastes were prepare in orer to achieve the objective of this stuy. Four types of Portlan cements, which are presente in Table 1, were use. In Table 1, AC stans for the clinker content in each cement. Table 1 The calculate Bogue compositions of these cements (mass fractions) were euce from the chemical characterization (Table 1). In orer to get three ifferent values of cement fineness, cement types C2 an C3 were use separately an one mixture (namely MF3, see Table 2) was prepare by mixing these two cements in a ratio of /. This can be one because of very similar chemical composition of these cements. A similar proceure was use in orer to obtain three values of C 3 A. Cement types C3 an C4 were use for this purpose (see Table 2). Table Reproucibility In orer to check the reproucibility of the methos, the tests on mixture MC13 were repeate 3 times before some other mixtures were teste. Fig. 1a an 1b present the results, measure by the wave transmission metho an the Vicat Neele test, respectively. The inherent scattering in this test was very small an the equipment's reproucibility very high. This statement turne out to be vali for most other experiments conucte using the evice escribe. Fig. 1.

7 4. Experimental results 4.1 General evolution of Fig. 2a an 2b show a typical UPV curve an the first erivative of the UPV curve uring the first 24 hours for the cement paste mixture, obtaine by our experiments, respectively. Some researchers ivie the evolution of of ifferent cement-base materials into three stages [, 7, 11, 1]. However, within this stuy, four stages are efine (see Fig. 2a). At stage 1, no was observe. During this ormant inuction perio, ultrasonic waves propagate through the water-like viscous suspension. After a certain time, usually between 2 an 6 minutes, epening on the w/c ratio, T, CT, BS, an AC3A, ultrasonic waves coul be obtaine at any time [7]. The measure velocity of approximately 3 m/s was observe at the beginning of stage 2 for all mixtures. This value is lower than the in water (143 m/s) an air (34 m/s). There exist two theories which explain this phenomenon. Accoring to Rapoport et al. [16], this can be explaine by the highly elongate length of the wave-path because of the suspene cement grains in fresh cement-base materials. Fig. 2. Accoring to Keating [17] an Sayers [18], this phenomenon is cause by the air entrappe in the paste because of a certain amount of air bubbles in the mixing water, or a huge number of tiny air bubbles that are entrappe in the paste uring mixing. Within the secon stage, the wave velocity then increases graually up to levels close to those foun in water. After a certain time, epening on the w/c ratio, T, CT, BS, an AC3A, the first inflection point IP1 appears near this value for all mixtures (see Fig. 2b). This point is efine as the en of stage 2 in this stuy. The increase of can only be attribute to the formation of hyration proucts that have no, or very little, influence on the penetration resistance, measure by the Vicat Neele test. is strongly affecte by the formation of ettringite crystals at this stage. At stage 3, graually increases to approximately 3 m/s, again epening on the w/c ratio, T, 6

8 CT, BS, an AC3A. Within this stage, the secon inflection point IP2 appears (see Fig. 2b). After that, the plateau is reache an only a small increase of can be observe after the en of stage 3. This behaviour can be explaine by a ecrease in the volume of water an an increase in the amount of hyration proucts with the progress of cement hyration in the cement paste. A fully connecte soli frame is forme [11]. This plateau is efine as stage 4 in this stuy. 4.2 Influence of iscusse parameters on the evolution of In Fig. 3, the influence of the iscusse parameters on the evolution of is briefly presente. Therefore, the sensitivity of the ultrasonic wave transmission metho on the hyration an formation of structure of ifferent cement pastes can be clearly observe from this Fig. Fig. 3a shows the influence of the w/c ratio on the evolution of. As expecte, mixtures with a higer w/c ratio show lower values of the ultrasonic pulse velocity, which can be relate to the microstructure of the cement paste. The evolution of was foun to be in a close relationship with volume fraction of total an connecte soli phase an it is well known that these two quantities are higher in the case of lower w/c ratio [11]. Fig. 3b shows the influence of the cement type on the evolution of. It can be seen that cement type has a significant influence on the evolution. The influence of the environmental temperature on the evolution of is shown in Fig 3c. It can be seen that the higher environmental temperature results in a more rapi evolution of at the very beginning. After the plateau is reache, the temperature shows less influence on the ultrasonic pulse velocity. This is in goo agreement with the results, obtaine by Ye [11]. The influence of the cement fineness is shown in Fig 3. It can be seen that the cement fineness has an important influence on the evolution of, especially at the very beginning of the hyration process. As expecte, higher fineness results in a more rapi hyration process [19] an consecutively to the more rapi evolution of. Fig. 3e shows the influence of the amount of tri-calcium aluminate (C 3 A) together with the influence of cement fineness. Even though cement type C4 has higher fineness than cement type C3 (see Table 1), it has a lower amount of C 3 A, which finally results in the slower evolution of. Therefore, it can be conclue that lower amount of C 3 A results in a slightly slower evolution of. 7

9 Fig. 3.. Estimation of the initial setting time of cement pastes with the ultrasonic wave transmission metho To achieve the objective of this stuy, the evolution of was compare with the evolution of the penetration of the Vicat Neele test for each cement paste mixture, separately. Accoring to [1], the initial setting time of cement is efine as the time when the istance, between the neele an the base plate, is 6 ± 3 mm (see Section 2.2). Therefore, the times when these istances were 3 mm an 9 mm were labelle as t3 an t9, respectively. Fig 4 shows the comparison between an for each mixture. Fig. 4. Alternatively to times t3 an t9 etermine by Vicat Neele test, the initial setting time, IST, is etermine from the results of UPV measurements: t IP1 is efine as the time of the first inflection point on the UPV curve, whereas t w correspons to the time when the ultrasonic pulse velocity reaches the ultrasonic pulse velocity in water (143 m/s). In Fig. the comparison between the interval t3-t9 an values t IP1 an t w for ifferent values of w/c ratio, curing temperature, cement fineness, an type of cement is shown. A shaowe area inicates the interval between t3 an t9 values, etermine with stanar Vicat neele metho. It is evient that the time interval between t3 an t9 values is narrow an that t IP1 an t w values correspon very well with the t3 an t9 values. Fig.. It is well known, that the lower w/c ratio, higher curing temperature, an higher cement fineness, results in a shorter initial setting time [19]. These phenomena can be also observe from Fig a, Fig b, an Fig c, respectively. 8

10 The values of, which correspon to the times t3, t9, an t IP1 are enote as 3, 9 an IP1 in this stuy, respectively. It can be seen from Table 3 that these values are very close to the value of in water (143 m/s). Moreover, the values of 3, 9 an IP1 are quite similar for all cement paste mixtures. The average value of 3 was 3 ' = 141. m/s, the average value of 9 was 9 ' = 14.7 m/s, an the average value of IP1 was IP1 ' = m/s. Therefore, accoring to this stuy, the initial setting time of an arbitrary cement paste can be efine very accurately by the time when the first inflection point appears on the UPV curve. An alternative approach woul be to efine the initial setting time as the time when the value reaches a value between 14 m/s an 14 m/s, or the time when the value of reaches the value of in water, which occurs near the inflection point on an arbitrary UPV curve. Table 3 6. Conclusions The ability of the ultrasonic wave transmission metho to estimate the initial setting time of ifferent cement pastes was stuie in this paper. It was shown that the propose wave transmission metho can be use very effectively to monitor the hyration an formation of the structure of an arbitrary cement paste mixture. For the iscusse variable ata set, the propose wave transmission metho appeare to be appropriate an effective for a quick an reliable estimation of the initial setting time of an arbitrary cement paste mixture. The initial setting time can be efine very accurately by the first inflection point on the ultrasonic pulse velocity curve. Alternatively, one can also estimate the initial setting time by the time when the ultrasonic pulse velocity of the longituinal waves reaches a selecte value within the suggeste narrow interval, close to the value of the velocity of longituinal ultrasonic waves in water. The latter estimate is slightly less accurate. This statement seems to be true for an arbitrary cement paste mixture. 9

11 Therefore, accoring to this stuy, the estimation of the initial setting time of the cement paste with the ultrasonic wave transmission metho is practical, reliable, an has a prospect of application in construction practice. Acknowlegements The work of G. Trtnik was financially supporte by the Ministry of Eucation, Science an Sport, of the Republic of Slovenia, uner contract The support is gratefully acknowlege. References [1] EN 196-3:2, Methos of testing cement - Part 3: Determination of setting times an sounness, April 2. [2] ASTM C 43-88, Stanar test metho for Time of Setting of Concrete Mixtures by Penetration Resistance, American society for testing an materials, [3] M. I. Valič, Hyration of cementitious materials by pulse echo USWR metho, apparatus an application examples, Cement an Concrete Research 3 (1) (2) [4] H. W. Reinhart, C. U. Grosse, Continuous monitoring of setting an harening of mortar an concrete, Construction an builing materials 18 (3) (24) [] C. U. Grosse, H. W. Reinhart, New evelopments in quality control of concrete using ultrasoun, Non-Destructive Testing in Civil Engineering, International Symposium NDT-CE (23). [6] T. Voigt, C. U. Grosse, Z. Sun, S. P. Shah, H. W. Reinhart, Comparison of ultrasonic wave transmission an reflection measurements with P- an S-waves on early age mortar an concrete, Materials an Structures 38 (2) [7] T. Kamaa, S. Uchia, K. Rokugo, Non-estructive evaluation of setting an harening of cement paste base on ultrasonic propagation characteristics, Journal of Avance Technology 3 (3) (2) [8] M. Krauss, K. Hariri, Determination of initial egree of hyration for improvement of early-age properties of concrete using ultrasonic wave propagation, Cement an Concrete Composites 28 (4) (26)

12 [9] T. Voigt, Z. Sun, S. P. Shah, Comparison of ultrasonic wave reflection metho an maturity metho in evaluating early-age compressive strength of mortar, Cement an Concrete Composites 28 (4) (26) [1] T. Voigt, G. Ye, Z. Sun, S. P. Shah, K. Van Breugel, Early age microstructure of Portlan cement mortar investigate by ultrasonic shear waves an numerical simulation, Cement an Concrete Research 3 () (2) [11] G. Ye, Experimental stuy an numerical simulation of the evelopment of microstructure an permeability of cementitious materials, PhD Theses, Delft, 23. [12] Z. Sun, T. Voight, S. P. Shah, Rheometric an ultrasonic investigations of viscoelastic properties of fresh Portlan cement pastes, Cement an Concrete Research 36 (2) (26) [13] T. Voigt, T. Malonn, S. P. Shah, Green an early age compressive strength of extrue cement mortar monitore with compressive tests an ultrasonic techniques, Cement an Concrete Research 36 () (26) [14] T. Chotar, N. Gimet-Brert, A.Smith, D. Fargeto. J. P. Bonnet, C. Gault, Application of ultrasonic testing to escribe the hyration of calcium aluminate cement at the early age, Cement an Concrete Research 31 (3) (21) [1] H. K. Lee, K. M. Lee, Y. H. Kim, H. Yim, D. B. Bae, Ultrasonic in-situ monitoring of setting process of high-performance concrete, Cement an Concrete Research 34 (4) (24) [16] J. R. Rapoport, J. S. Popovics, V. K. Subramaniam, S. P. Shah, Using ultrasoun to monitor stiffening process of concrete with amixtures, ACI Mater. J. 97 (2) [17] J. Keating, D. J. Hannant, A. P. Hibbert, Comparison of shear moulus an pulse velocity techniques to measure the buil-up of structure in fresh cement pastes use in oil well cementing, Cement an Concrete Research 19 (4) (1989) [18] C. M Sayers, R. L. Grenfell, Ultrasonic propagation through hyrating cements, Ultrasonics 31, (3) (1993) [19] P. C. Hewlett, Lea's Chemistry of Cement an Concrete, Elsevier, Burlington MA,

13 Table 1 Characteristics of cements cement type label AC [%] BS [cm 2 /g] C 3 S [%] C 2 S [%] C 3 A [%] C 4 AF [%] CEM II/A-S, 42.R C1 > CEM I, 2. R C2 > CEM I, 42. N C3 > CEM I, 42. N SR C4 >

14 Table 2 Cement paste mixtures Mixture Cement T [ C] w/c BS [cm 2 /g] C 3 A [%] MC13 C MC14 C MC1 (REF), MT1 C MT2 C MT3 C MC2, MF1 C MC3, MF2, MC3A1 C MC4, MC3A2 C MF3 C2, C MC3A3 C3, C MC24 C MC34 C

15 Table 3 Initial setting time ata for all cement paste mixtures Mixture characteristic points [hours] Value of [m/s] label t3 t9 t IP1 t w 3 9 IP1 MC MC MC1, MT MT MT MC2, MF MC3, MF2, MC3A MC4, MC3A MF MC3A MC MC

16 a) b) MC13/1 2 MC13/2 2 2 MC13/ MC13/1 MC13/2 MC13/ Fig. 1. Reproucibility of the methos. a) Ultrasonic wave transmission metho - UPV curves, b) Vicat Neele metho - VNM curves.

17 a) b) rate [km/s 2 ] IP1 IP Fig. 2. Typical UPV curve for the cement paste. a) Evolution of the, b) rate of the evolution.

18 a) b) 4. MC13 MC14 MC1 MT1 MT2 MT3 c) ) e) MC3A1 MC3A2 MC3A3 4. MC2 MC3 MC4 MF1 MF2 MF3 Fig. 3. The influence of the iscusse parameters on the evolution of. a) The influence of the w/c ratio, b) the influence of cement type, c) the influence of the curing temperature, ) the influence of the cement fineness, e) the influence of the cement composition.

19 a) b) e) f) 3 c) ) g) h)

20 4. k) l) i) j) Fig. 4. The relationship between an for all cement paste mixtures. a) mixture MC13, b) mixture MC14, c) mixture MC1, MT1, ) mixture MT2, e) mixture MT3, f) mixture MC2, MF1, g) mixture MC3, MF2, MC3A1, h) mixture MC4, MC3A2, i) mixture MF3, j) mixture MC3A3, k) mixture MC24, l) mixture MC34.

21 a) b) IST [hours] w/c ratio IST [hours]. c) ) 8 t3-t9 7 IST [hours]. 6 4 t3-t T [ C] IST [hours] BS [cm 2 /g] C2 C3 C4 Cement type Fig.. The influence of some of the iscusse parameters on the t3-t9 interval, t w, an t IP1. a) The influence of the w/c ratio, b) the influence of the cement fineness c) the influence of the curing temperature, ) the influence of the cement type. t w t IP1 t w t IP1 t3-t9 t w t IP1 t3-t9 t w t IP1