Author(s) Attari, Azadeh; McNally, Ciaran; Richardson, Mark G.

Transcription

1 Provided by the author(s) and University College Dublin Library in aordane with publisher poliies. Please ite the published version when available. Title Numerial Model for Quantifying Degree of Hydration in Conrete Mixes with Redued CO2 Footprint Author(s) Attari, Azadeh; MNally, Ciaran; Rihardson, Mark G. Publiation date Conferene details Item reord/more information Numerial Modeling Strategies for Sustainable Conrete Strutures, Aix-en-Provene, Frane, May 29- June1, Downloaded T20:56:31Z The UCD ommunity has made this artile openly available. Please share how this aess benefits you. Your story matters! Some rights reserved. For more information, please see the item reord link above.

2 Numerial Model for Quantifying Degree of Hydration in Conrete Mixes with Redued CO2 Footprint A. Attari, C. MNally, M.G. Rihardson Shool of Civil, Strutural and Environmental Engineering, University College Dublin, Ireland Abstrat The widespread appliation of innovative ementitious ombinations in onrete raises the need for more omprehensive investigation of the resulting onrete properties. Early age behaviour is a major fator to be addressed, and tools are required for quantifying the hydration state of onrete members, partiularly at early-ages. Numerial models an potentially be used in mass onrete onstrution to predit and prevent possible thermal rak formation. They also provide an indiret means for haraterizing development of the hydration reation in onrete. The latter an then be utilised in modelling and prediting seondary onrete properties, suh as diffusion oeffiient. This is gaining inreasing importane as we harness the ability to develop innovative ombinations. The ement industry is estimated to be responsible for about 7% of the arbon dioxide generated globally. As suh, reduing the amount of CO 2 emitted during ement prodution is a key issue if the onstrution industry is to fully partiipate in sustainable development. Under the terms of the Kyoto Protool Emissions Trading Sheme it is also potentially profitable for ement ompanies to redue their CO 2 emissions. By using blended ement instead of ordinary Portland ement, it is possible to lower the share of linker in ement, resulting in redued CO 2 and energy emissions. In Ireland, CEM II now aounts for over 80% of the Irish ement prodution portfolio. GGBS is a by-produt of steel industry and a ommon replaement for ement. When ompared to Portland ement it has a redued CO 2 footprint and onretes ontaining GGBS are less prone to deterioration due to aggressive hemial attaks. Its use has the potential to produe more durable onrete with inreased servie life, lower maintenane osts and a lower arbon footprint, inreasing the sustainability of onrete onstrution. The aim of the urrent study is to use numerial models to quantify the development of heat of hydration when mixtures of CEM II and GGBS are utilised. Experiments were onduted the temperature profiles in 4 different mixes of onrete (CEM II with 0%, 30%, 50% and 70% GGBS) are reorded. This was ahieved by asting 6 idential onrete samples from eah mix, with thermoouples embedded to reord the internal temperature of the mix at regular time steps. Temperature hanges of the mix are then used to quantify the heat evolved, based on the priniples of heat transfer. To aount for the ombined effet of time and temperature on hydration development, ativation energy of the mix is used, along with the equivalent age maturity method. Total heat of hydration is determined based on the omposition and amount of ementitious materials. It has long been aepted that the liberated heat of hydration, divided by the total available heat of hydration is a good measure of the degree of hydration. The experimental data desribing hydration development with equivalent age are then used to alibrate the exponential formulation presenting the S-shaped hydration urve. Values of β, τ, and α u (the hydration parameters) are obtained for eah mix, from the results of multivariate non-linear regression analysis. Comments on the use of this method in quantifying onrete hydration are then made. 1. Introdution Conrete, with estimations of more than 10 billion tons prodution worldwide, has an enormous impat on the environment, whether through the natural resoures it onsumes as 1

3 the raw material, or through the energy onsumption and the huge amount of CO 2 released as a result of ement prodution [1]. It has been estimated that the ement industry is responsible for about 7% the total CO 2 generated worldwide [2]. Reduing this figure is of great importane for the ement industry to ontribute signifiantly in the onstrution setor s ontribution to global sustainable development. The key ingredient in prodution of Portland ement is ement linker. It is an intermediate produt, resulting from alination of limestone and subsequent fusion with lay minerals. The linker is then removed from the kiln to ool, ground to a fine powder, and mixed with a small fration (about five perent) of gypsum to reate the most ommon form of ement known as Portland ement [3]. The reation of onverting limestone to lime, involves the release of large quantities of CO 2 : CaCO 3 + Heat CaO + CO 2 Moreover, the ement manufaturing proess requires that materials be heated to temperatures in exess of 1400 o C to ahieve full fusion between the lime and lay minerals. If the arbon footprint resulting from this heating is also taken into aount, the prodution of one tonne of Portland ement leads to the release of approximately 0.95 tonnes of CO 2 [4]. Sine 1995, the ement industry has ommitted itself to dereasing their CO 2 emissions, in order to ontribute to sustainability and global warming prevention [5]. However, the limited ability to redue CO 2 emissions in manufaturing ordinary Portland ement neessitates the development of alternative ement binders. One approah to do this is to replae OPC with blended ements in order to lower the share of linker in the final produt [6]. Additions suh as ground granulated blastfurnae slag (GGBS) -whih is a by-produt of steel industry- or fly ash, an be mixed with linker to produe blended ements. Sine these additions redue the overall demand for linker, they will result in more environmental friendly ements. They have already been in use aross the Europe for several years, though their appliation depends on the loal availability of the linker substitutes. The perentage replaement of linker an vary from 5% up to typially 70% (although higher replaement values are tehnially possible). In effet, the lower the share of linker, the lower the CO 2 emission assoiated with the ement [7]. Blastfurnae slag (BS), a by produt of the steel industry if quenhed by water forms a glassy material known as granulated blastfurnae slag (GBS), whih an show hydrauli properties when in ontat with water. Grinding this material to a fine powder (GGBS) enhanes it properties as a ement replaement material. The rate of its reation with water is slow; however, when mixed with Portland ement, the alkalis and sulphates released during ement hydration an at as ativators to raise the hydration rate of GGBS [8]. Conrete ontaining GGBS has a higher proportion of alium siliate hydrates (CSH), the ingredient that ontributes to the onrete strength. This leads to prodution of onrete with a higher ultimate strength ompared to the onrete made with OPC. Moreover, this type of onrete ontinues to gain strength over time, and has been shown to double its 28 day strength over periods of 10 to 12 years [9]. GGBS also enhanes the durability and resistane of onrete against aggressive environments. It an be used in large volume onrete pours to limit exessive temperature rises. It auses the heat to be generated more gradually, with lower peaks and less total heat of hydration, limiting thermal gradients in onrete. Exessive thermal gradients an lead to formation of miro-raks and onsequent redution in durability. Constituents suh as GGBS -also known as Seondary Cementitious Materials- an either be used in ombination with other ements in the onrete at time of mixing, or an be used as a partial replaement for linker during the ement prodution proess to produe a single-powder blended ement. Blended ements involving high levels of GGBS replaement an lead to long-term performane enhanement in aggressive environments, ompared to Portland ement alone [8]. They are suitable in most appliations; however, onsideration must be given to the possibility that other harateristis of the onrete might 2

4 be affeted as a result, e.g. initial strength, drying time, resistane to seawater attak [7]. Widespread appliation of innovative ementitious ombinations undersores the need for more lose investigations of properties of the resulting onrete. One of the important fields to be addressed is the early-age behaviour of onrete. To be able to develop a model that predits the in-plae early-age and even long-term performane of onrete, an aurate estimate of the hydration development of the mix should be made [10]. This development an be haraterised by the degree of hydration and by hydration urves based on three key parameters. The degree of hydration (α) is a measure that quantifies how far the reations between water and ementitious materials have progressed. It is defined as the ratio between the quantity of hydrated ement grains and the original quantity of ement grains available in the mix. Hydration degree inreases with age and onrete maturity. The uring temperature of the mix is also another influential parameter. Different approahes have been proposed to quantify the degree of hydration of onrete mixes. Some are diret approahes, aimed at measuring the quantity of ement gel formed in the mix, while others are indiret methods, estimating the degree of hydration based on the amount of hemially-bound water or the amount of heat released during hydration [11]. The indiret method based on the released heat of hydration has been adopted in this study to develop the hydration urves. The hydration urve an then be used in haraterization of the hydration behaviour of onrete mixes at a speifi uring temperature, known as the referene temperature (T r ). Temperature sensitivity of the mix and the equivalent age maturity method an then be employed to predit the behaviour under various uring temperatures enountered in pratie. Therefore, numerial models are sought to haraterize the hydration development of onrete speimens in their early-age. These models an then be implemented in prediting related onrete properties, suh as permeability and diffusivity. These properties are influened by pore size distribution and the strutural formation of rystals within the paste, whih in turn, are affeted by hydration development and the rate of heat generation. Numerial models an also be used in prediting early-age strength gain of onrete and estimating the amount of heat generated during hydration. Knowledge of the heat release patterns is essential in large onrete pours, to avoid high temperatures and exessive thermal gradients, whih an lead to durability problems in the resulting onrete. Currently, limited guidane is available for haraterizing the hydration behaviour of mixes, espeially when Seondary Cementitious Materials are used. The purpose of this study is to ontribute to addressing this gap in the guidane available. This is ahieved by determining hydration urve parameters through an experimental study of onrete mixes made using CEM II binders with varying replaement levels of GGBS. 2. Experimental programme: materials and methods Materials A laboratory program was designed to monitor the heat generated during hydration of four different onrete mixes, omprising limestone aggregates, CEM II A-LL (Irish soure) and various replaement levels of GGBS, ranging from 0 to 70%. Table 1 provides a summary of the onrete mixtures tested. Hydration haraterization urves were derived from measured data and use of published methodologies for determining the degree of hydration and the equivalent age onept. From eah onrete mix, six ubi speimens, 30*30*15 m eah, were ast. Embedded thermoouples were used to reord the internal temperature of speimens. Heat of hydration was then alulated for eah mix, based on the average values reorded in these samples. Temperature monitoring was arried out for several days after bathing, until the temperature stabilised. To prevent exessive heat loss to the environment, insulation boards, 2 m thik were used to seal off the onrete speimens while they are being ured. 3

5 One the degree of hydration development and equivalent age of speimens were determined using the experimental data, multivariate non-linear regression analyses were performed, to obtain the orresponding values of hydration urve parameters for eah mix Table 1: Material proportions for the four different mixes used in the experiment. Mix GGBS level (%) Cement Content (kg/m 3 ) GGBS Content (kg/m 3 ) Fine aggregate (kg/m 3 ) C10 aggregate (kg/m 3 ) C20 Aggregate (kg/m3) Water Content (kg/m 3 ) Methodology for quantifying the degree of hydration based on the released heat It has been widely aepted that the umulative amount of heat evolved at time t of the hydration proess, divided by the total amount of heat available at 100% hydration, an be used as the measure of degree of hydration [11, 12]: H(t) (t) HT α(t): degree of hydration at time t H(t): umulative heat generated from time 0 to time t (J/g) H T : Total heat generated assuming omplete hydration (J/g) (1) Cements have various hemial ompositions, and eah of their onstituents has been found to have a unique heat of hydration [10]. One the perentage of eah phase is known in the ement paste (e.g. using Bogue formulations) the total heat of hydration of ement at full hydration (H em ) an be quantified using equation 2. H em 500p C3S 260p C2S 866p C3A 420p C4AF 624p SO3 1186p FreeCaO 850p MgO (2) H em : p i : total heat of hydration of ement (J/g) weight ratio of the i-th ompound in terms of total ement ontent In the urrent study, the onrete mix is a blend of ement and GGBS. To quantify the total heat of hydration of the ementitious system, the heat of hydration of GGBS is also required, and based on previous researh it has been onsidered to be 461 J/g [13]. Equation 3 an then be used to alulate the total heat of hydration of ementitious system, when a mixture of ement and GGBS is used: Hu H em p em 461p slag (3) H u : p i : total heat of hydration of ementitious material (J/g) weight ratio of the i-th omponent in terms of total ement ementitious materials 4

6 With knowledge of the total ementitious materials ontent per unit volume of onrete ( ), the ultimate heat of hydration at 100% hydration an be alulated using Equation 4: HT Hu H T : total ultimate heat of hydration of ement (J/m 3 ) : ementitious materials ontent in unit volume of onrete (g/m 3 ) (4) Methodology for Charaterizing the Hydration Behaviour Curves One the evolved heat of hydration of the onrete mixes has been experimentally determined, and the degree of hydration development estimated, a best-fit mathematial model an be proposed to represent the data [11]. In this urrent study, the exponential formulation presented in equation 5 has been used. It is shown to aurately represent the s- shape of the hydration development urve [14, 15]: (t ) e u.exp( [ ] ) t e (5) t e : equivalent age at the referene temperature (T r ) α u : ultimate degree of hydration β: hydration shape parameter τ: hydration time parameter (hours) The hydration urve parameters (α u, β, τ) represent the amount of aeleration, retardation, rate and ultimate degree of hydration in different mixes, with τ being relevant to the timing of the aelerating part, and β indiating the rate of hydration [12]. In pratie, the hydration proess almost always stops before the ement is totally onsumed, and a degree of hydration of 100% may never be reahed [17]. α u has been introdued to the equation to allow for this effet to be onsidered in the hydration urve mathematial model. This variable is strongly affeted by the water-ement ratio of the mix, though it remains unaffeted by the uring temperature [16-18]. The other parameter in equation 5 (t e ), represents the equivalent age of a speimen ured at the referene temperature (T r ). Curing temperature has the most signifiant effet on the rate of hydration [19, 20]. Therefore, to determine maturity of a onrete speimen, uring temperature should also be taken into aount, along with the hronologi uring age. To be able to aount for the ombined effet of time and temperature, the maturity method and equivalent age funtion developed by Freiesleben, Hansen and Pedersen [19] is used. This non-linear funtion (equation 6) onverts the atual age (t) of a onrete speimen ured at any temperature (T ) to an equivalent uring age (t e ), assuming the sample has been ured at the referene temperature (T r ) [20]: t (T ) e r t exp( E R 1 ( 273 T 1 )). t 273 T 0 r (6) t e (T r ): equivalent age at the referene uring temperature (h) Δt: hronologial time interval (h) T : average onrete temperature during the time interval Δt ( C) T r : referene temperature ( C) 5

7 E: ativation energy (J/mol) R: universal gas onstant, J/mol/K In equation 6, 'ativation energy' (E) indiates the temperature sensitivity of a onrete mixture [10]. Several formulations have been proposed to alulate this parameter for a mix. The model developed by Shindler [11] is employed here: E 22,100f f E (p E p slag C3A ) 0.3 (p C4AF ) 0.25 Blaine 0.35 (7) p i : weight ratio of the i-th ompound in terms of total ement ontent Blaine: speifi surfae area of ement (m 2 /kg) f E : ativation energy modifiation fator when GGBS is added to the mix Methodology for quantifying the heat generation of the mix By monitoring the temperature development of a onrete mixture during hydration, the amount of heat generated an be quantified. Unless the onrete speimens are ured in a fully-adiabati ondition, there is always an amount of heat-loss in the system, and temperature development is not as high as the adiabati temperature rise. This amount of heat-loss should also be onsidered, when alulating the total heat evolved in the system, up to the time t, to give us the value of H(t) to be used in equation 1. The heat generated due to ement hydration raises the internal temperature of onrete speimens. During the first days after asting, the rate of hydration is higher and results in a onsiderable temperature build-up in the speimens. The differene between onrete and ambient temperature will result in a heat flow to the environment, whih an be quantified based on the laws of heat transfer. Here, the one-dimensional heat diffusion equation (equation 8) has been used [21]: d(t T Q A dt amb ) x Q: the rate of heat loss (J/h) ρ: density of the insulation slab (kg/m 3 ) : speifi heat apaity of the slab (J/kg/K) A: surfae area of the insulation slab (m 2 ) δx: T : T amb : thikness of the insulation board (m) internal temperature of the onrete samples ( C) ambient temperature ( C) t: time (h) The net amount of heat aptured inside the speimens, responsible for raising the internal temperature of onrete an also be quantified using equation 9 [11]: dh dt dt dt p (8) (9) 6

8 Speifi heat of onrete is one of the parameters that is used in quantifying the amount of heat generated in the hydration proess. This parameter does not remain onstant during the early-age of onrete, sine it is highly influened by the amount of unbound water ontent in the mix, whih dereases over time, as the hydration degree progresses [22]. The following equation has been employed here to aount for the hanges in speifi heat apaity of onrete in early-age [23]: p 1 (W.. ef W.(1 ). W. a a W w. w ) (10) ef 8.4T C 339 p : speifi heat apaity of onrete (J/kg/K) ρ: density of the insulation slab (kg/m 3 ) W,a,w : weight ratio of ement, aggregate and water in onrete mix (kg/m 3 ),a,w: speifi heat of ement, aggregate and water (J/kg/K) ef : speifi heat of hydrated ement (J/kg/K) α: degree of hydration T : onrete temperature ( C) Using this approah, the amount of heat loss, and the net heat responsible for temperature rise of onrete an both be quantified at disrete times after bathing. The sum of these two values is the total heat generated in the hydration proess, H(t), to be used in equation Results Figure 1 summarizes the results obtained during temperature monitoring of the mixes (measured onrete temperatures), along with the adiabati temperature development, alulated based on the laws of heat transfer. It may be seen that, as expeted, the peak temperature drops with inreasing levels of GGBS but the profile of the umulative heat generated over time inreases with inreasing levels of GGBS. The results show that the maximum temperatures reahed during hydration derease with inreased. Figure 2 represents the heat evolution trends notied in the mixes. These are the diagrams of the total heat released by eah mix, during their hydration proess, alulated based on the laws of heat transfer, and using the temperatures reorded over the first week of monitoring the speimens. The parameters whih determined the s-shape hydration urves, based on the results of regression analyses, are shown in Table 2. Table 2: Hydration parameters obtained from regression analysis of experimental data (T r = 21.1 C) No Mix Desription E (J/mol) H u (J/g) α u τ β 1 CEM II CEM II + 30% GGBS CEM II + 50% GGBS CEM II + 70% GGBS

9 Total Heat Released (kj) Temperature (C) Temperature (C) Temperature (C) Temperature (C) Temperature Profiles OPC Time (hours) Figure 1- a Temperature Profiles OPC-30% GGBS Time (hours) Figure 1- b Temperature Profiles OPC-50% GGBS Time (hours) Temperature Profiles OPC-70% GGBS Time (hours) Figure 1- Figure 1- d Figure 1: Measured semi-adiabati vs. ideal temperature rise (assuming no heat loss) OPC 30% GGBS 50% GGBS 70% GGBS Time (hours) Figure 2: Profile of the total heat released during the hydration proess of the 4 mixes The hydration haraterization urves, produed by substituting the values of hydration urve parameters for eah mix (given in table 2) in equation 5 are shown in Figure 3, and an be utilised in prediting the degree of hydration development of the mixes. 8

10 Figure 3: S-shaped hydration haraterization urves 4. Disussion As it an be seen in the results, inreasing the amount of GGBS delays the start of the aeleration stage. This is refleted in the inreasing hydration time parameters (τ), whih double in value as the ement replaement level goes from 0% to 70%. The rate of hydration development, (the slope of hydration urve during the aeleration stage) slows down as the perentage level of GGBS inreases in the mix. As a result, the values obtained for the hydration rate parameter (β in table 2) redue by a fator of 2 as the ement replaement level goes from 0% to 70%. Equally, a trend is observed by the total heat released by the end of temperature monitoring is dereasing, whih results in the values alulated for α u to derease from to While onsidering the equations proposed in the literature for estimating the values of this parameter, inreasing the amount of GGBS in the mix, should in fat inrease the ultimate degree of hydration of the resulting onrete [10]. This an be attributed to the fat that the rate of heat generation slows down onsiderably in mixes with higher levels of GGBS (50% and more). This might imply that the duration of temperature monitoring onsidered in this study (1 week) has not been long enough for the hydration proess in a GGBS ontaining mixture to reah degrees of hydration lose to their atual α u. This hypothesis an be undersored by the fat that by the end of the first week after bathing, the reorded internal temperatures of onrete had not stabilized with the ambient temperature. Also, in Figure 3, omparison of the hydration haraterization urves obtained for different mixes shows that in the ase of the mix with 70% GGBS, the s-shape hydration urve has not been ompletely formed by the end of the 1st week. Considering all of these, one may suggest that in order to investigate the hydration of mixtures ontaining high levels of GGBS, the temperature monitoring period should be extended beyond 1 week. In order to address this, and to be able to obtain more preise estimates of α u, another solution would be to adopt the more diret approah for determining the degree of hydration, rather than using the heat of hydration development. Another study is urrently being arried out to investigate this. In the new study the degree of hydration will be evaluated based on analysis of bak-sattered eletron mirosope images taken from onrete speimens at different ages. 5. Conlusions Comparison of the values obtained for hydration urve parameters (Table 2) with those reported in the literature for mixtures based on CEM I, shows a onsiderable differene, whih reflets the signifiantly different hydration behaviour of ement/addition ombinations. 9

11 This emphasises the need for further validation studies of the appliation of numerial models based on the parameters whih determine hydration urves. Aknowledgement The authors would like to aknowledge the support of the TEAM projet. TEAM is a Marie Curie Initial Training Network and is funded by the European Commission 7 th Framework Programme (PITN-GA ). Referenes [1] Meyer, C. The greening of the onrete industry, Cement & Conrete Composites; 31, p , [2] Malhotra, VM. Role of supplementary ementing materials in reduing greenhouse gas emissions, In: Gjorv OE, Sakai K, editors, Conrete tehnology for a sustainable development in the 21st entury, London: E&FN Spon; p , [3] Gibbs, MJ, Soyka, P, Conneely, D & Kruger, M. CO 2 Emissions from Cement Prodution, Good Pratie Guidane and Unertainty Management in National Greenhouse Gas Inventories, [4] Van Oss, HG & Padovani, AC. Cement manufature and the environment: part II, Environmental hallenges and opportunities, Journal of Industrial Eology; 7(1), p , [5] Zementwerke VD. Environmental Data of the Cement Industry, [6] Bassioni, G. A study towards greener onstrution, Journal of Applied Energy, [7] Fraunhofer Institute for Systems and Innovation Researh. Methodology for the free alloation of emission allowanes in the EU ETS post 2012, Setor report for the ement industry, By order of the European Commission, Eofys projet Number: PECSNL082164, November [8] Pavía, S & Condren, E. A study of the durability of OPC vs. GGBS onrete on exposure to silage effluent, Journal of Materials in Civil Engineering; 20(4), p , [9] Smolzyk, HG. Durability and pore struture on very old onretes (Dauerhaftigkeit und Porenstruktur von sehr alten Betonen), Beton-Informationen 26, Heft 1, [10] Shindler, AK & Folliard, KJ. Influene of supplementary ementing materials on the heat of hydration of onrete, Advanes in Cement and Conrete IX Conferene; Copper Mountain Conferene Resort in Colorado, August 10-14, [11] Shindler, AK & Folliard, KJ. Heat of hydration models for ementitious materials, ACI Materials Journal, Title 102-M04, January-February [12] Folliard, KJ, Juenger, M, Shindler, AK, Riding, K, Poole, J, Kallivokas, LF, Slatnik, S, Whigham, J & Meadows, L. Predition Model for Conrete Behavior, Tehnial Report, Center for Transportation Researh, The University of Texas at Austin, Report No. FHWA/TX-08/0-4563, May [13] Kishi, T & Maekawa, K. Thermal and mehanial modeling of young onrete based on hydration proess of multi-omponent ement minerals, RILEM Symposium on Thermal Craking in Conrete at Early Ages, Edited by R. Springenshmid, E & EF Spon, London, p , [14] Freiesleben Hansen, P & Pedersen, EJ. Curing of Conrete Strutures, Draft DEB-Guide to Durable Conrete Strutures, Appendix 1, Comité Euro-International du Béton, Switzerland, [15] Pane, I & Hansen, W. Conrete Hydration and Mehanial Properties under Non-isothermal Conditions, ACI Materials Journal, 99(6), p , Nov-De [16] Mills, RH. Fators Influening Cessation of Hydration in Water-Cured Cement Pastes, Report No. 90, Highway Researh Board, Washington D.C., p ,

12 [17] Taplin, JH. A Method for Following the Hydration Reation in Portland Cement Paste, Australian Journal of Applied Siene, 10(3), p , [18] Kjellsen, KO, Detwiler, RJ & Gjørv, OE. Development of Mirostruture in Plain Cement Pastes Hydrated at Different Temperatures, Cement and Conrete Researh, 21(1), p , [19] Freiesleben Hansen, P & Pedersen, EJ. Maturity Computer for Controlling Curing and Hardening of Conrete, Nordisk Betong, 1(19), p , [20] Shindler, AK. Effet of temperature on hydration of ementitious materials, ACI Materials Journal, Title 101-M09, January-February [21] Lienhard, JH. A Heat Transfer Textbook, Prentie-Hall, [22] Neville, AM. Properties of onrete, Longman, [23] Shindler, AK. Conrete Hydration, Temperature Development and Setting at Early Ages, PhD dissertation, University of Texas at Austin,