The microstructural and compositional changes within the cement paste exposed to high temperatures were monitored by XRD, FTIR, TGA/DTA and SEM techniques to understand the nature of decomposition of C-S-H gel and the associated physicomechanical properties of thermally damaged cement paste. OPC paste (w/c ratio 0.27) was hydrated for 28 days then fired up to 750°C for 2 hours (heating rate 10°C/min). The relative mass percent of calcium hydrates and portlandite was estimated by calculations derived from TGA results. Beyond 450°C, the percentage of portlandite sharply diminishes and C-S-H progressively decomposes into C2S and C3S until complete loss of calcium hydrates content occurs at 750°C. An increase of the total porosity, severe loss in mechanical strength and propagation of harmful cracks occurs. The thermal shock as a result of cooling of the heated cement paste and the rehydration of lime enhance the propagation of harmful cracks.
Poon, C.S., Azhar, S., Anson, M. and Wong, Y.L. (2003) Performance of Metakaolin Concrete at Elevated Temperatures. Cement and Concrete Composites, 25, 83.
Khoury, G.A. (1992) Compressive Strength of Concrete at High Temperatures: Reassessment. Magazine of Concrete Research, 44, 291. https://doi.org/10.1680/macr.1992.44.161.291
Jhang, K.Y. (2009) Non Linear Ultrasonic Techniques for Non Destructive Assessment of Micro Damage in Material: A Review. International Journal of Precision Engineering Manufacturing, 10, 123. https://doi.org/10.1007/s12541-009-0019-y
Park, S.J., Yim, H.J. and Kwak, H.G. (2014) Non Linear Resonance Vibration Method to Estimate the Damage Level on Heat-Exposed Concrete. Fire Safety Journal, 69, 36.
Netinger, I., Varevac, D., Bjegovic, D. and Moric, D. (2013) Effect of High Temperature on Properties of Steel Slag Aggregate Concrete. Fire Safety Journal, 59, 1.
Ezziane, M., Kadri, T., Molez, L., Jauberthie, R. and Belhacen, A. (2015) High Temperature Behavior of Polypropylene Fibers Reinforced Mortars. Fire Safety Journal, 71, 324.
Ergun, A., Kurklu G., Basplnar, M.S. and Mansour, M.Y. (2013) The Effect of Cement Dosage on Mechanical Properties of Concrete Exposed to High Temperatures. Fire Safety Journal, 55, 160.
Reddy, D.V., Sobhan, K., Liu, L. and Young Jr, J.D. (2015) Size Effect on Fire Resistance of Structural Concrete. Engineering Structures, 99, 468.
Xiao, J., Li, Z., Xie, Q. and Shen, L. (2016) Effect of Strain Rate on Compressive Behavior of High-Strength Concrete after Exposure to Elevated Temperatures. Fire Safety Journal, 83, 25.
Kontogeorgos, D.A., Semitelos, G.K., Mandilaras, I.D. and Founti, M.A. (2016) Experimental Investigation of the Fire Resistance of Multi-Layer Drywall Systems Incorporating Vacuum Insulation Panels and Phase Change Materials. Fire Safety Journal, 81, 8.
Wang, H.Y. (2008) The Effects of Elevated Temperature on Cement Paste Containing GGBFS. Cement and Concrete Composites, 30, 992.
Alonso, C. and Fernandez, L. (2004) Dehydration and Rehydration Processes of Cement Paste Exposed to High Temperature Environments, Materials Science, 39, 3015. https://doi.org/10.1023/B:JMSC.0000025827.65956.18
Peng, G.F. and Huang, Z.S. (2008) Change in Microstructure of Hardened Cement Paste Subjected to Elevated Temperatures. Construction and Building Materials, 22, 593.
Ai, H., Young, J.F. and Scherer, G.W. (2001) Thermal Expansion Kinetics: Method to Measure Permeability of Cementitious Materials: II, Application to Hardened Cement Pastes. Journal of the American Ceramic Society, 84, 385. https://doi.org/10.1111/j.1151-2916.2001.tb00666.x
Liu, X., Ye, G., De Schutter, G., Yuan, Y. and Taerwe, L. (2008) On the Mechanism of Polypropylene Fibres in Preventing Fire Spalling in Self-Compacting and High-Performance Cement Paste. Cement and Concrete Research, 38, 487.
Xu, Y., Wong, Y.L., Poon, C.S. and Anson, M. (2003) Influence of PFA on Cracking of Concrete and Cement Paste after Exposure to High Temperatures. Cement and Concrete Research, 33, 2009.
Heikal, M. (2000) Effect of Temperature on the Physico-Mechanical and Mineralogical Properties of Homra pozzolanic Cement Pastes. Cement and Concrete Research, 30, 1835.
Morsy, M.M., Shebl, S.S. and Rashad, A.M. (2008) Effect of Fire on Microstructure and Mechanical Properties of Blended Cement Pastes Containing MK and SF. ASIAN Journal of Civil Engineering (Building and Housing), 9, 93.
Rashad, A.M. and Zeedan, S.R. (2012) A Preliminary Study of Blended Pastes of Cement and Quartz Powder under the Effect of Elevated Temperature. Construction and Building Materials, 29, 672.
El-Didamony, H., Abd El-Rahman, E. and Osman, R.M. (2012) Fire Resistance of Fired Clay Bricks-Fly Ash Composite Cement Pastes. Ceramics International, 38, 201.
Morsy, M.S., Galal, A.F. and Abo-EI-Enein, S.A. (1998) Effect of Temperature on Phase Composition and Microstructure of Artificial Pozzolana-Cement Pastes Containing Burnt Kaolinite Clay. Cement and Concrete Research, 28, 1157.
Tantawy, M.A., El-Roudi, A.M., Abdalla, E.M. and Abdelzaher, M.A. (2013) Fire Resistance of Sewage Sludge Ash Blended Cement Pastes. Journal of Engineering.
Stepkowska, E.T., Blanes, J.M., Franco, F., Real, C. and Pérez-Rodriguez, J.L. (2004) Phase Transformation on Heating of an Aged Cement Paste. Thermochimica Acta, 420, 79.
Heikal, M. (2006) Effect of Temperature on the Structure and Strength Properties of Cement Pastes Containing Fly Ash Alone or in Combination with Limestone. Ceramics Silikaty, 50, 167.
Alarcon-Ruiz, L., Platret, G., Massieu, E. and Ehrlacher, A. (2005) The Use of Thermal Analysis in Assessing the Effect of Temperature on a Cement Paste. Cement and Concrete Research, 35, 609.
Ukrainczyk, N., Ukrainczyk, M., šipušic, J. and Matusinovic, T. (2006) XRD and TGA Investigation of Hardened Cement Paste Degradation. 11th Conference on Materials, Processes, Friction and Wear, Vela Luka.
Ye, G., Liu, X., De Schutter, G., Taerwe, L. and Vandevelde, P. (2007) Phase Distribution and Microstructural Changes of Self-Compacting Cement Paste at Elevated Temperature. Cement and Concrete Research, 37, 978.
Zhang, Q. and Ye, G. (2012) Dehydration Kinetics of Portland Cement Paste at High Temperature. Journal of Thermal Analysis and Calorimetry, 110, 153. https://doi.org/10.1007/s10973-012-2303-9
Khoury, G.A., Majorana, C.E., Pesavento, F. and Schrefler, B.A. (2002) Modeling of Heated Concrete. Magazine of Concrete Research, 54, 77.
Rehsi, S.S. (1993) Portland Fly Ash Cement in Mineral Admixtures in Cement and Concrete. Edited by Ghosh, S.N., Sarkar, S.L., and Harsh, S., ABI Books, New Delhi, 158.
Mendes, A., Sanjayan, J.G., Gates, W.P. and Collins, F. (2012) The Influence of Water Absorption and Porosity on the Deterioration of Cement Paste and Concrete Exposed to Elevated Temperatures, as in a Fire Event. Cement and Concrete Composites, 34, 1067.
Maaroufi, M.A., Lecomte, A., Diliberto, C., Francy, O. and Brun, P. (2015) Thermo-Hydrous Behavior of Hardened Cement Paste Based on Calcium Aluminate Cement. European Ceramic Society, 35, 1637.
Vysvaril, M., Bayer, P., Chroma, M. and Rovnanikova, P. (2014) Physico-Mechanical and Microstructural Properties of Rehydrated Blended Cement Pastes. Construction and Building Materials, 54, 413.
Lin, W.M., Lin, T.D. and Powers-Couche, L.J. (1996) Microstructures of Fire Damaged Concrete. ACI Materials, 93, 199.
Poon, C.S., Azhar, S., Anson, M. and Wong, Y. (2001) Strength and Durability Recovery of Fire Damaged Concrete after Post-Fire-Curing. Cement and Concrete Research, 30, 1307.
Shui, Z., Xuan, D., Wan, H. and Cao, B. (2008) Rehydration Reactivity of Recycled Mortar from Concrete Waste Experienced to Thermal Treatment. Construction and Building Materials, 22, 1723.
Serpell, R. and Lopez, M. (2013) Reactivated Cementitious Materials from Hydrated Cement Paste Wastes. Cement and Concrete Composites, 39, 104.
ASTM Designation (1983) C109-80, Standard Test Methods for Compressive Strength of Hydraulic Cements. Annual Book of ASTM Standards.
Kumar, S. and Kameswara Rao, C.V.S. (1995) Strength Loss in Concrete Due to Varying Sulfate Exposures. Cement and Concrete Research, 25, 57.
Pavlik, J., Tydlitat, V., Cerny, R., Klecka, T., Bouska, P. and Rovnanikova, P. (2003) Application of a Microwave Impulse Technique to the Measurement of Free Water Content in Early Hydration Stages of Cement Paste. Cement and Concrete Research, 33, 93.
Gennaro, R., Cappelletti, P., Cerri, G., Gennaro, M., Dondi, M. and Langella, A. (2004) Zeolitic Tuffs as Raw Materials for Lightweight Aggregates. Applied Clay Science, 25, 71.
Copeland, L.E. and Hayes, T.C. (1956) Porosity of Hardened Portland Cement Pastes. American Concrete Institute, Materials, 27, 633.
ISO (1983) 5018:1983, Determination of True Density of Refractory and Other Raw Materials.
Földvári, M. (2011) Handbook of Thermogravimetric System of Minerals and Its Use in Geological Practice. Geological Institute of Hungary, Budapest.
Dolado, J.S., Griebe, M. and Hamaekers, J. (2007) A Molecular Dynamic Study of Cementitious Calcium Silicate Hydrate (C-S-H) Gels. Journal of the American Ceramics Society, 90, 3938.
Zhang, B. (2011) Effects of Moisture Evaporation (Weight Loss) on Fracture Properties of High Performance Concrete Subjected to High Temperatures. Fire Safety Journal, 46, 543.
Saad, M., Abo-El-Enein, S.A., Hanna, G.B. and Kotkata, M.F. (1996) Effect of Temperature on Physical and Mechanical Properties of Concrete Containing Silica Fume. Cement and Concrete Research, 26, 669.
Rashad, A.M., Sadek, D.M. and Hassan, H.A. (2016) An Investigation on Blast-Furnace Slag as Fine Aggregate in Alkali Activated Slag Mortars Subjected to Elevated Temperatures. Journal of Cleaner Production, 112, 1086.
Alonso, M.M., Palacios, M. and Puertas, F. (2013) Effect of Polycarboxylate-Ether Admixtures on Calcium Aluminate Cement Pastes. Part 2: Hydration Studies. Industrial and Engineering Chemistry Research, 52, 17330. https://doi.org/10.1021/ie401616f
Matossi, F. (1949) Vibration Frequencies and Binding Forces in Some Silicate Groups. Journal of Chemical Physics, 17, 679. https://doi.org/10.1063/1.1747369
Bakharev, T. (2005) Geopolymeric Materials Prepared using Class F Fly Ash and Elevated Temperature Curing. Cement and Concrete Research, 35, 1224.
Gadsden, J.A. (1975) Infrared Spectra of Minerals and Related Inorganic Compounds. 3rd Edition, Butterworths, London.
Liew, Y.M., Kamarudin, H., Mustafa Al Bakri, A.M., Luqman, M., Khairul Nizar, I., Ruzaidi, C.M. and Heah, C.Y. (2012) Processing and Characterization of Calcined Kaolin Cement Powder. Construction and Building Materials, 30, 794.
Vedalakshmi, R., Sundara Raj, A., Srinivasan, S. and Ganesh Babu, K. (2003) Quantification of Hydrated Cement Products of Blended Cements in Low and Medium Strength Concrete using TG and DTA Technique. Thermochimica Acta, 407, 49.
Mitchell, L.D. and Margeson, J.C. (2006) The Effect of Solvents on C-S-H as Determined by Thermal Analysis. Journal of Thermal Analysis and Calorimetry, 86, 591.
European Committee for Standardization (2000) Cement: Common Cements. PrEN 197-1, CEN/TC51/WG 6 rev., Final Draft.
Mobasher, B. (2002) Hydration, Best 50 Minutes, Undergraduate Faculty Development. NSF Center for Advanced Cement Based Materials, Northwestern University.
Jennings, H.M. (2008) Refinements to Colloid Model of C-S-H in Cement: CM-II. Cement and Concrete Research, 38, 275.
Boynton, R.S. (1980) Chemistry and Technology of Lime and Limestone. John Wiley and Sons, New York.
Platret, G. (2002) Monitoring the Hydration of Cement and the Evolution of Solid Phases in Concrete by Thermal Analysis. Microstructural Characteristics and Properties Related to the Durability of Concrete. Methods of Measuring and Testing Laboratory, Test Methods No. 58, Central Laboratory of Bridges and Roads, Paris.
Wang, H., Alfredsson, V., Tropsch, J., Ettl, R. and Nylander, T. (2013) Formation of CaCO3 Deposits on Hard Surfaces: Effect of Bulk Solution Conditions and Surface Properties. ACS Applied Material Interfaces, 5, 4035. https://doi.org/10.1021/am401348v
Petzold, A. and Rohr, M. (1970) Concrete for High Temperatures. Maclaren and Sons, London.