Effect of curing conditions on the durability of ultra-high performance concrete under flexural load

Abstract

We experimentally investigated the effect of curing conditions on the durability of UHPC under flexural load. Moreover, the mechanisms of the effect of curing conditions were revealed from the microstructural point of view with environmental scanning electron microscopy (ESEM) and X-ray computerized tomography (X-ray CT). The experimental results show that the flexural load has negative influence on the durability of UHPC, but UHPC still exhibits excellent durability under flexural load. Besides, the curing conditions do show influences on the durability of UHPC. Compared with standard and steam curing, oven curing led to a lower chloride resistance and freeze-thaw performance of UHPC. The microstructure of UHPC paste was detected with ESEM. It is revealed that, compared with standard and steam cured UHPC, the lower reaction degree and internal microcracks are the causes for the lower chloride resistance of oven cured UHPC. The defects distribution in UHPC before and after freeze-thaw action was investigated with X-ray CT. The number of defects in oven cured UHPC increases the fastest during the freeze-thaw action due to its more defective microstructure

Keywords

UHPC / curing condtions / durability / flexural load / microstructure

References

[1] Buitelaar P. Ultra High Performance Concrete: Developments and Applications during 25 Years[EB/OL]. http://download. contecaps. com/index.php?id=927&tx_mpdownloadcenter_pi1%5Bcategorie%5D=285 &cHash=cfb25835f3d023e0871ccd62b60aa32a

[2] Schmidt M a, Fehling E. Ultra-High-Performance Concrete: Research Development and Application in Europe[C]. Proceeding of the 7th International Symposium on the Utilization of High-strength/High-performance Concrete. Special Publication, 2005 51-78.

[3] Ba MF, Qian CX, Guo XJ, et al. Effects of Steam Curing on Strength and Porous Structure of Concrete with Low Water/Binder Ratio[J]. Construction and Building Materials, 2011, 25(1): 123-128.

[4] Yang SL, Millard SG, Soutsos MN, et al. Influence of Aggregate and Curing Regime on the Mechanical Properties of Ultra-high Performance Fibre Reinforced Concrete (UHPFRC)[J]. Construction and Building Materials, 2009, 23(6): 2291-2298.

[5] Yazici H. The Effect of Curing Conditions on Compressive Strength of Ultra High Strength Concrete with High Volume Mineral Aadmixtures [J]. Building and Environment, 2007, 42(5): 2083-2089.

[6] Wang C, Yang C, Liu F, et al. Preparation of Ultra-High Performance Concrete with Common Technology and Materials[J]. Cement and Concrete Composites, 2012, 34(4): 538-544.

[7] Wille K, Naaman AE, EI-Tawil S, et al. Ultra-high Performance Concrete and Fiber Reinforced Concrete: Achieving Sstrength and Ductility without Heat Curing[J]. Materials and Structures, 2011, 45(3): 309-324.

[8] Naaman AE, Wille K. The Path to Ultra-high Performance Fiber Reinforced Concrete(UHP-FRC): Ffive Decade of Progress[C]. Proceeding of 3rd International Symposium on UHPC and Nanotechnology for High Performance Construction Materials. Kassel: Kassel University Press, 2012 3-13.

[9] Talebinejad I, Bassam SA, Iranmanesh A, et al. Optimizing Mix Proportions of Normal Weight Reactive Powder Concrete with Strengths of 200-350 MPa[C]. Proceeding of International Symposium on Ultra-high Performance Concrete. Kassel: Kassel University Press, 2004 133-141.

[10] Roy DM, Gouda GR, Bobrowsky A. Very High Strength Cement Pastes Prepared by Hot Pressing and Other High Pressure Techniques [J]. Cement and Concrete Research, 1972, 2(3): 349-366.

[11] Yazici H, Yardimci MY, Aydin S, et al. Mechanical Properties of Reactive Powder Concrete Containing Mineral Aadmixtures under Different Curing Regimes[J]. Construction and Building Materials, 2009, 23(3): 1223-1231.

[12] Arunachalam K, Vigneshwari M. Experimental Investigation on Ultra High Strength Concrete Containing Mineral Admixtures under Different Curing Conditions[J]. International Journal of Civil and Structural Engineering, 2011, 2(1): 33-42.

[13] Graybeal B, Tanesi J. Durability of an Ultrahigh-Performance Concrete[J]. Journal of Materials in Civil Engineering, 2007, 19(10): 848-854.

[14] Mu L, Sun W, Miao CW. Sulfate Attack of High Strength Concrete on the Action of Pre-loading[J]. Industrial Construction, 1999, 29(8): 52-63.

[15] Feng X, Garboczi EJ, Benz BP, et al. Estimation of the Degree of Hydration of Blended Cement Pasted by a Scanning Electron Microscope Point-counting Procedure[J]. Cement and Concrete Research, 2004, 34(10): 1787-1793.

[16] Sun W, Zhao S. Characterizing the Microstructure of UHPCC with High-volume Fly Ash Addition by Nanoindentation[C]. Proceedings of 13th International Congress on the Chemistry of Cement. Madrid: Abstract book, 2011 399

[17] Eppers S, Muller C. Autogenous Shrinkage Strain of Ultra-High-Performance Concrete (UHPC)[C]. Proceeding of the 2nd international symposium on Ultra High Performance Concrete. Kassel: Kassel University Press, 2008 433-441.

[18] Scheydt JC, Muller HS. Microstructure of Ultrahigh Performance Concrete (UHPC) and Its Impact on Durability[C]. Proceeding of 3rd International Symposium on UHPC and Nanotechnology for High Performance Construction Materials. Kassel: Kassel University Press, 2012 349-356.

[19] El-Dieb AS. Mechanical, Durability and Microstructural Characteristics of Ultra-high-strength Self-compacting Concrete Incorporating Steel Fibers[J]. Materials and Design, 2009, 30(10): 4286-4292.