Research Article. Hydration process study on the alkali-activated slag cementing materials

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1 Available online wwwjocprcom Journal of Chemical and Pharmaceutical Reearch,, ():88 Reearch Article ISSN : CODEN(USA) : JCPRC5 Hydration proce tudy on the alkaliactivated lag cementing material Xiaohui Yuan *, Yan Yan, Zhean Lu and Liming Yu School of Civil Engineering and Architecture, Wuhan Univerity of Technology, China School of Civil Engineering and Architecture, Hubei Univerity of Technology, China ABSTRACT The hydration proce of alkaliactivator lag(aas) cementing material wa tudied by ultraonic, and AAS hydration heat wa tet too by changing the environment temperature, activator module The reult how that the hydration proce of AAS can be divided into three tage: the initial phae hydrolyi, hydration acceleration period and table phae The hydration rate and hydration heat of the AAS material will remarkably accelerate a the temperature raie The appearing time of the peak value of the hydration exothermic curve of the alkali activated cementitiou material delay a the activator module increae, and the peak value alo gradually decreae Key word: Hydration proce, alkaliactivator lag, odule, Environment temperature, INTRODUCTION The hydration of AAS cementing material mean the chemical reaction after the combination of the levigated uperfine lag powder and the alkali activated liquor The earliet alkaliactivated theory wa put forward by Purdon, etc[] In hi reearch on the cement hydration proce, he find that NaOH can make aluminoilicate eaily diolve into NaSiO and NaAlO, thoe product then react with CH (calcium hydroxide) and create hydration calcium metailicate and calcium chlorate, after the hardening of cement, it will again generate NaOH, in the whole proce, NaOH act a a catalyi to the hardening proce of cement The hydration proce of AAS cement i known to differ ignificantly from that of the Portland cement by the rapid reaction during the early hour, cauing the quick trength development a well Ettringite i the dominant hydration product after three hour that give the early trength[]amorphou Al(OH) 3 may alo be formed, but could not be identified in the Xray diffraction (XRD) pattern[3] The hydration factor that affect lag cement which excited by alkali are varied and complicated[5] The feature of uperfine lag powder itelf, the variety and doage of activator[8], the doage of admixture[9], and the environmental temperature[] all have huge influence on the hydration and heat releae of alkali inpire lag cementing material In thi tudy, the ultraonic i ued to tet the hydration proce of the AAS cementing material, and the hydration proce i analyied from chemical point of view In addition effect of the environment temperature, activator module to AAS hydration react heat i invetigated EXPERIENTAL SECTION aterial The oxide compoition of material obtained by uing the Xray fluorecence (XRF) technique are lited in Table The lag i a water quenched lag with denity of 35 g/cm 3 SE image of the lag are hown in Fig and it particle ize ditribution i plotted in Fig3 The fig i the SE image of the flyah Three different olution are prepared in the experiment, ie the water gla liquid, NaOH olution and deionized water The coare aggregate are crahed limetone gravel izing between 535 mm 8

2 Xiaohui Yuan et al J Chem Pharm Re,, ():88 Table Oxide compoition of material (ma%) aterial GGBS Water gla NaOH SiO AlO3 9 FeO3 3 CaO 7 7 go 8 KO 59 NaO TiO 7 SO LOI The activator olution conit of water gla liquid, NaOH and water (extra water added to the olution) NaOH wa added to change the n modulu (SiO to NaO molar ratio) of the activator olution NaOH Na O + H O The chemical compoition of olid odium metailicate i 77% NaO and 3% SiO The molecular formula of commercially available indutrial odium ilicate i NaO nsio, odium ilicate modulu () i the ratio of fraction mole of ilicon dioxide and the fraction mole of odium oxide According to modulu definition, the odium ilicate modulu can be adjuted through the introduction of odium oxide The following form i the calculated mode: Fig SE image of the lag Alkaline activator modulu Referring GB / T 98 "indutrial odium ilicate" norm of China to tet the odium ilicate modulu, and get the NaO a Fraction i %, the SiO a Fraction i 738%, o the the odium ilicate modulu i %/ %) Solid content of the water gla liquid i 375% The table i the compoition of the activator olution The activator olution modulu i 5 Table i the reconciliation heet of alkali activator in different module Table Alkaline activator modulu adjuting table odule Sodium ilicate atching Wt% NaOH Initial Final 3 5 Time/min Fig The relationhip between the alkali activated modulu and etting time A large amount of tet found that when the activator modulu i between and, AAS cementing material can be eaily molded, mixing i eaily conducted during the molding proce, and the proce ha high mobility, and ha higher trength in d Figure how that when the modulu of the activator range from to, a the module increae, the ample initial etting time and final etting time gradually increae The ample whoe module i 9 ha the longet etting time But it initial etting time and final etting time are very hort The initial etting time i 3 minute, it final etting time i only 7 minute Hydration heat A to the above alkali activated cementing material, in the mix proportion of tatic lurry, the activator module are, 5, and, when doing the tet of the proce of the hydration exothermic changing tet a the time change, the tet intrument of PTSS digital cement hydration heat meaurement ytem, the tet method refer 8

3 Xiaohui Yuan et al J Chem Pharm Re,, ():88 to GB/T 9598 The Determination ethod of Cement Hydration Heat Figure 3 how the alkali activated cementitiou material hydration exothermic curve under different modulu and ame doage of odium ilicate Fig3 The alkali activated cementitiou material hydration exothermic curve under different modulu Fig 3 how that under the ame condition, the appearing time of the peak value of the hydration exothermic curve of the alkali activated cementitiou material delay a the activator module increae, and the peak value alo gradually decreae It i mainly becaue a the activator module decreae, the initial baicity of the olution will increae, the content of NaOH alo increae, according to the alkaliactivated theory, the increae of NaOH in the olution will accelerate the early hydration of the alkali activated cementitiou material, o under the condition of low module activator, the early hydration reaction i more fierce, the related peak value of hydration temperature will alo be in advance Figure and figure 5 are the hydration heat releae curve after the combination of 5mg lag and alkaliactivator olution under the condition of and From figure and 5, the hydration heat releae curve of AAS cementing material and portland cement[9] are very imilar According to the piecewie form of hydration heat releae curve of portland cement, the hydration heat releae proce of the AAS cementing material can alo be divided into 5 tage: (I) Quick reaction period OA (the early period of induction); (II) Induction period AB; (III) Acceleration period BC (late induction period); (IV) Deceleration period; (V) Stabilization period DE (diffuion control period) In the quick reaction period, when the environmental temperature i, the peak value of hydration heat releae curve of cementing material i mw, it appear at 3h, while the temperature i,the peak value of hydration heat releae curve of cementing material i 755mw,it appear at 73h Thi how that when the environmental temperature rie from to, the peak value of hydration heat releae curve of cementing material dramatically increae In the third period of acceleration, when the environmental temperature i, the peak value of hydration heat releae curve of cementing material i 8mw, it appear at 8h While the temperature i, the peak value of hydration heat releae curve of cementing material i 3mw, appear at 3h At, the average value of the total amount of hydration heat releae of the alkali activated cementing material i 87 J/g Under the ame condition, at, the average value of the total amount of hydration heat releae of the alkali activated cementing material i 395 J/g Under the ame condition, the heat releae of inorganic cementing material at i 87 time of that at By the above analyi data, under the ame condition, a the temperature rie, the rate of hydration heat releae of the alkali activated cementing material accelerate, the total amount of hydration heat releae increae Heal Flow b(mw) A B Heat:87(J/g) t:and7(h) Peak aximum:9(degree C)/33h Onet:(Degree C)/7(h) Baeline Type:Linear C Time(h) Fig hydration exothermic curve D E Heal Flow i b(mw) 8 C A B O Heat:395(J/g) t:and7(h) Peak aximum:393(degree C)/73h Onet:3935(Degree C)/9(h) Baeline Type:Linear Time(h) Fig5 hydration exothermic curve Hydration proce The hydration proce tet ued Pundit lab Ultraonic teter produced by PROCEQ Teting Intrument company D E 8

4 Xiaohui Yuan et al J Chem Pharm Re,, ():88 in Switzerland To undertake ultraonic tet The teting apparatu are howed in fig Via teting the wave velocity change of alkali activated cementitiou material and the tet on ultraonic, it hydration proce can be reflected During the teting proce, in order to get the early hydration wave velocity of the lurry, the ample molding proce hould be eriouly controlled After the mixing of the lurry, it hould be quickly put into the ultraonic teting mold and be vibrated tenely, then the two tet probe of ultraonic hould be intantly aimed at both ide of the mold center, butter wa ued a the coupling agent between the probe and the mold, then fix the probe, open the intrument, and et the parameter The data of the whole tet wa collected by computer, the interval etting of the data wa collected once per minute A regard to the laboratory condition, the temperature hould be controlled at ±3, the humidity hould be controlled at 7±% Fig 7 i the cementing material ultraonic wave velocity change with time diagram with 35 water olid ratio, 5 alkali excitation agent module It can be een that 3 minute before teting, the ultraonic wave velocity lowly increae, oon afterward, the wave velocity muhroomed A the hydration continue, around minute, the ultraonic wave velocity obviouly lowed down, then flattened out, and the hydration rate dramatically declined The figure how that the inflection point of Point A and Point B ha roughly the ame condenation time with alkali activated cementitiou material Via ultraonic wave velocity change with time diagram of fig 7, the hydration proce of alkali activated cementitiou material ytem can be roughly divided into three tage: the initial phae hydrolyi, hydration acceleration period and table phae The firt tage: the reaction happened in the initial phae hydrolyi are mainly that after the fue of alkali activated cementitiou material ytem (olid phae) and alkaliactivator olution (liquid phae), odium ilicate gradually hydrolyzed, a large number of OH wa formed in the olid phae olution, at the ame time, a large amount of Si(OH) wa formed A the reaction continued, Si(OH) wa reolved into active SiO The whole proce i a heat releaing reaction, it produced ma hydration heat, but during the whole proce, the olid phae almot did not take part in the hydration reaction, thi i the main reaon why early ultraonic wave velocity i not high Second tage: hydration acceleration period Hydration heat produced in the firt tage make the SiO, AlO and CaO in the urface of the olid phae eaier to crack with the polarization of OH, the olid and table net tructure in the urface of the olid phae wa detroyed OH wa carried into the inner part of the phae Amount of Ca + formed in the pore of the olid phae, theee poitive ion reacted with active SiO diolved and produced in the firt tage and produce a large amount of CSnot hydrated A a reult, the whole ytem i well connected When the connection reached a certain degree, the gelatin, thi gelatin connect the olid phae particle which are hydrated and ytem tranformed from platomer to elatomer The whole proce happened around 3 minute to minute during the hydration The third tage: the CSH gelatin product wa formed in the econd tage, a the reaction continued, the gelatin gradually incaed the olid phae urface, and it became thicker and thicker A the exit of the incaed layer, the liquor phae and the olid phae were iolated The olid phae particle could not continue to get OH, o a polarization reaction would not occur A a reult, the olid phae connectivity could not continue to increae Thu, at thi moment, the ultraonic wave velocity became lower becaue it could not increae any more velocity(m/) 9 3 point B point A 8 time(m min) Fig Ultraonic automatic acquiition intrument Fig 3 ultraonic wave velocity change with time diagram RESULTS AND DISCUSSION AAS cementing material can be eaily molded and mixing i eaily conducted when the activator modulu i between and The AAS cementing material initial etting time and final etting time gradually increae with the the modulu of the activator increaed from to The temperature can remarkably effect the hydration heat and the production of the AAS cementing hydration i the main reaon why the Velocity change during tet 83

5 Xiaohui Yuan et al J Chem Pharm Re,, ():88 CONCLUSION The AAS cementing material initial etting time increaed by improving the activator modulu Increaing the external temperature can remarkably increaed the hydration of AAS cementing material The hydration proce of AAS can bee divided into three tage: the initial phae hydrolyi, hydration acceleration period and table phae REFERENCES [] Purdon A O J Soc Chem Ind, 9, 59:9 [] W Chen H J H Brouwer J ater Sci 7; : 83 [3] Winnefeld, F and B Lothenbach Cement and Concrete Reearch,, (8): 397 [] XU Hua, Deventer J S J Inter J ineral Proc,, 59(3):7 [5] Yip C K, Lukey G C, Provi J L, Cem Concr Re, 8, 38:5555 [] Shi, C and Day, R L Cement and Concrete Reearch, 995, 5(), 3333 [7] Shi,Cand Day,RL Cement and Concrete Reearch, 99, (3), 398 [8] Krizan, D And Zivanovic, B Cement and Concrete Reearch,,3(8):888 [9] Puerta,F, Palomo, A,FernandezJimenez, A, Jzqyuerdi, JZ and Granizo, L Advance in Cement Reearch, 3,5():38 [] FernandezJimenez, A And Puerta, F ateriale de Contruction, 997,7():3 8