Hydration evolution of pre-cast concrete with steam and water curing

Abstract

The hydration characteristics of pre-cast concrete considering the effects of effective initial steam-curing and water-curing duration were measured and analyzed with XRD, TG, X-ray CT, SEM-BSE and MIP techniques. The results show that the effective initial steam-curing duration for pre-cast concrete with lower water-binder ratio was 10–14 h at 50 °C and the initial water-curing duration was 7–14 d. And the hydration evolution of cement, fly ash and slag in pre-cast concrete was obtained respectively by combining the hydrochlorides and EDTA selecting dissolution methods, based on which the contents of hydrated and anhydrate in concrete were calculated and the corresponding dynamic capillary porosity was also determined. Moreover, the comparison between calculated results and experimental ones indicates that the proposed evolution models of microscopic characteristics corresponding to hydration kinetics of cemented materials could be adopted to predict the developing trend of capillary porosity and hydration-products content in pre-cast concrete with fly ash and slag under certain curing conditions.

Keywords

microstructure evolution / hydration kinetics / effective curing condition / pre-cast concrete

References

[1] HuangS Y, JiangJ F, YangN YModern concrete technology [M], 2002Xi’anShaanxi Press of Science and Technology

[2] HuC Y, YuanX M, GaoX SStructure and performance of cement concrete [M], 1984BeijingChinese Construction Industry Press

[3] JawedI, SkalnyJ. Hydration of tri-calcium silicate in the presence of fly ash [C]. Proceedings of Symposium N, Effects of Fly Ash Incorporation in Cement and Concrete, 1981BostonMaterials Research Society60-70

[4] LinF, MeyerM C. Hydration kinetics modeling of Portland cement considering the effects of curing temperature and applied pressure [J]. Cement and Concrete Research, 2009, 39(8): 255-265

[5] NaviP, PignatC. Simulation of cement hydration and the connectivity of the capillary pore space [J]. Advanced Cement Based Material, 1996, 4(2): 58-67

[6] BentzD P. Three-dimensional computer simulation of Portland cement hydration and microstructure development [J]. Journal of American Ceramic Society, 1997, 80(1): 3-21

[7] CerveraM, FariaR, OliverJ, PratoT. Numerical modeling of concrete curing, regarding hydration and temperature phenomena [J]. Computers and Structures, 2002, 80(18/19): 1511-1521

[8] SchindlerA K, FolliardK J. Heat of hydration models for cementitious materials [J]. ACI Materials Journal, 2005, 102(1): 24-33

[9] PatelH H, BlandC H, PooleA B. The microstructure of concrete cured at elevated temperatures [J]. Cement and Concrete Research, 1995, 25(3): 485-490

[10] TaylorH F WChemistry of cement [M], 19972nd edLondonThomas Telford Services Ltd.

[11] LeaF MChemistry of cement and concrete [M], 19703rd edLondonEdward Arnold Ltd.

[12] PapadakisV G. Effect of fly ash on Portland cement systems Part I. Low-calcium fly ash [J]. Cement and Concrete Research, 1999, 29(11): 1727-1736

[13] PowersT C, BrownyardT L. Studies of the physical properties of hardened Portland cement paste [R]. Bulletin, vol. 22, 1948ChicagoResearch Laboratories of the Portland Cement Association

[14] LiX, YanP Y. Assessment method of hydration degree of cement in complex binder based on the calcium hydroxide content [J]. Journal of the Chinese Ceramic Society, 2009, 37(10): 1597-1603

[15] PapadakisV G. Effect of fly ash on Portland cement system part II: High-calcium fly ash [J]. Cement and Concrete Research, 2000, 30(10): 1647-1654

[16] SnyderK A, BentzD P. Suspended hydration and loss of freezable water in cement pastes exposed to 90% relative humidity [J]. Cement and Concrete Research, 2004, 34(11): 2045-2056

[17] PaneI, HansenW. Investigation of blended cement hydration by isothermal calorimeter and thermal analysis [J]. Cement and Concrete Research, 2005, 35(6): 1155-1164

[18] SaekiT, MonteiroP J M. A model to predict the amount of calcium hydroxide in concrete containing mineral admixtures [J]. Cement and Concrete Research, 2005, 35(6): 1914-1921