Effects of Ultraviolet Radiation, High Temperature and Alkaline Chemicals on Ageing of Silicone Sealants Used in Ballastless Track Expansion Joints

Abstract

Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation (UV), high temperature combined with the alkaline environment. To evaluate the durability and analyse the ageing mechanism, six one-component silicone sealants from different companies were selected and subjected to accelerated ageing tests including UV, thermal and alkali ageing treatments. The ageing effects on the performance of the sealants were evaluated via the appearance and the mechanical property changes. The changes in molecular structure were studied by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TG). This study revealed that different materials displayed different sensibilities to the ageing methods, in which 15 % – 20 % decreases of mechanical properties could be observed under UV radiation test, owning the most significant effects. Structure analysis showed that the physical changes of aggregative states were the principal factors to the performance, along with the chemical slight changes. The glossiness dropped significantly in ageing test, which could be used as one of the effective evaluation parameters for ageing conditions in the field.

Keywords

silicon / sealant / durability / ageing / expansion joints

References

[1] Zhai W, Zhao G, Yang J, et al. Chinese High Speed Railway[J]. Sci. World J., 2014, 12: 12-55.

[2] Esveld C. Recent Developments in Slab Track[J]. European Railway Review., 2003, 9(2): 81-85.

[3] Kawakami M, Omata F, Toyoda A. Current Status of Expansion Joints Used for Road Bridges in Japan and an Advanced Buried Joint[J]. Advanced Materials Research, 2015, 1129: 323-30.

[4] Liu S, Mo L, Wang K, et al. Preparation, Microstructure and Rheological Properties of Asphalt Sealants for Bridge Expansion Joints[J]. Constr. Build. Mater., 2016, 105: 1-13.

[5] Liu Z, Phares B M, Greimann L F. Use of Longitudinal Expansion Joints in Wide-Bridge Applications to Reduce Deck Cracking[J]. J. Bridge Eng., 2016, 21(10): 04016068

[6] Li G, Ji G, Meng H. Shape Memory Polymer-Based Sealant for a Compression Sealed Joint[J]. J. Mater. Civ. Eng., 2014, 27(6): 04014196

[7] Bleszynski RF, Thomas MD. Microstructural Studies of Alkali-silica Reaction in Fly Ash Concrete Immersed in Alkaline Solutions[J]. Advanced Cement Based Materials, 1998, 7(2): 66-78.

[8] Corporation China Raiway. Tentative Specification of Joint Sealants for the High Speed Railway Ballastless Track[S]. TJ/GW119-2013, 2013

[9] de Buyl F. Silicone Sealants and Structural Adhesives[J]. Int. J. Adhes., 2001, 21(5): 411-422.

[10] Boubakri A, Guermazi N, Elleuch K, et al. Study of UV-aging of Thermoplastic Polyurethane Material[J]. Materials Science and Engineering: A, 2010, 527(7-8): 1649-1654.

[11] Malla RB, Shrestha MR, Shaw MT, et al. Temperature Aging, Compression Recovery, Creep, and Weathering of a Foam Silicone Sealant for Bridge Expansion Joints[J]. J. Mater. Civ. Eng., 2010, 23(3): 287-297.

[12] Malla RB, Swanson BJ, Shaw MT. Laboratory Evaluation of a Silicone Foam Sealant Bonded to Various Header Materials Used in Bridge Expansion Joints[J]. Constr. Build. Mater., 2011, 25(11): 4132-4143.

[13] Tan K, White C, Benatti D, et al. Evaluating Aging of Coatings and Sealants: Mechanisms[J]. Polym. Degrad. Stab., 2008, 93(3): 648-656.

[14] Chew M, Zhou X. Enhanced Resistance of Polyurethane Sealants Against Cohesive Failure under Prolonged Combination of Water and Heat[J]. Polym. Test., 2002, 21(2): 187-193.

[15] Swanson BJ, Malla RB, Shaw MT. Laboratory Testing, Field Installation, and Monitoring of a Silicone Foam Sealant for Bridge Expansion Joints[J]. J. Mater. Civ. Eng., 2012, 18(8): 758-767.

[16] Rogers AD, Lee-Sullivan P, Bremner TW. Selecting Concrete Pavement Joint Sealants. II: Case Study[J]. J. Mater. Civ. Eng., 1999, 11(4): 309-316.

[17] Mirza J, Durand B, Bhutta AR, et al. Preferred Test Methods to Select Suitable Surface Repair Materials in Severe Climates[J]. Constr. Build. Mater., 2014, 50(0): 692-698.

[18] Dubault A, Deloche B, Herz J. Effect of Crosslinking Density on the Orientational Order Generated in Strained Networks: A Deuterium Magnetic Resonance Study[J]. Polymer, 1984, 25(10): 1405-1410.

[19] Mullins L. Effect of Stretching on the Properties of Rubber[J]. Rubber Chem. Technol., 1948, 21(2): 281-300.

[20] Zhang Y, Huang Y, Liu X, et al. Studies on the Silicone Resins Cured with Polymethylsilazanes at Ambient Temperature[J]. J. Appl. Polym. Sci., 2003, 89(6): 1702-1707.

[21] Haraguchi K, Farnworth R, Ohbayashi A, et al. Compositional Effects on Mechanical Properties of Nanocomposite Hydrogels Composed of Poly (N, N-dimethylacrylamide) and Clay[J]. Macromolecules, 2003, 36(15): 5732-5741.

[22] Yadav K, Morison K, Staiger MP. Effects of Hypochlorite Treatment on the Surface Morphology and Mechanical Properties of Polyethersulfone Ultrafiltration Membranes[J]. Polym. Degrad. Stab., 2009, 94(11): 1955-1961.

[23] Ihara T, Gustavsen A, Jelle BP. Sealant Aging and Its Correlation with Facade Reflectance[J]. Constr. Build. Mater., 2014, 69(0): 390-402.

[24] Safranski DL, Gall K. Effect of Chemical Structure and Crosslinking Density on the Thermo-mechanical Properties and Toughness of (Meth) Acrylate Shape Memory Polymer Networks[J]. Polymer, 2008, 49(20): 4446-4455.

[25] Yan X, Xu T, Chen G, et al. Synthesis of Diamond-like Carbon/nanosilica Composite Films by an Electrochemical Method[J]. Electrochem. Commun., 2004, 6(11): 1159-1162.

[26] Menefee E. Protein Crosslinking, 1977 Berhin: Springer.

[27] Furukawa K, Fujino M, Matsumoto N. Optical Properties of Silicon Network Polymers[J]. Macromolecules, 1990, 23(14): 3423-3426.

[28] Wang J, Ober CK. Self-organizing Materials with Low Surface Energy: the Synthesis and Solid-state Properties of Semifluorinated Side-chain Ionenes[J]. Macromolecules, 1997, 30(24): 7560-7567.

[29] Trenor SR, Shultz AR, Love BJ, et al. Coumarins in Polymers: from Light Harvesting to Photo-cross-linkable Tissue Scaffolds[J]. Chem. Rev., 2004, 104(6): 3059-3078.