Internal Relative Humidity and Drying Shrinkage of Lightweight Aggregate Concrete

Abstract:

In this paper, the influence of water cement ratio, prewetting degree of lightweight aggregate, flyash content and air content on the internal relative humidity (IRH) and drying shrinkage of lightweight aggregate concrete (LAC) were studied using a relative humidity sensor and drying shrinkage apparatus. Results showed that the IRH of concrete decreased rapidly at early age and slowed down at late age, and prewetting lightweight aggregate could compensate the loss of IRH. The effect of compensation could be enhanced with the increasing of prewetting degree of lightweight aggregate, and the addition of flyash retarded the decrease of IRH at early age. The drying shrinkage of LAC increased quickly at early stage and it slowed down to the even after 60 days or longer age. Furthermore, the drying shrinkage of LAC increased with increasing of water cement ratio. The effect of air content on the drying shrinkage of LAC was limited at early stage. However, at the late stage it grew at different level with increasing of air content. By raising the prewetting degree of lightweight aggregate, mixing with proper dosage of flyash, the shrinkage rate of LAC can be reduced markedly. Key words: lightweight aggregate concrete, internal relative humidity, drying shrinkage, prewetting degree, flyash.

• Periodical: Key Engineering Materials (Volumes 629-630)
• Pages: 473-480
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.629-630.473
• Online since: October 2014
• Authors: Xiu Hua Zheng*, Yu Feng Zhai, Shi Zuo Zhan, Shu Jie Song
• Keywords: Drying Shrinkage, Fly Ash (FA), Internal Relative Humidity, Lightweight Aggregate Concrete, Prewetting Degree

References

[1] Y. Zhu, Y.F. Xu, J. Chen: Application and development trend of haydite lightweight aggregate concrete, Journal of Wuhan Institute of Urban Construction, 18 (2) (2001), pp.67-70.

[2] F.Z. Wang, Q.J. Ding, Y.Z. Chen, et. al. : Study on Shrinkage of High Strength Lightweight Aggregate Concrete. Journal of Building Materials, 6(4) (2003), pp.431-435.

[3] S.H. Dong, Y. Ge, B.S. Zhang, et. al.: Analysis of Relative Humidity Change in Low Water-cement Ratio Concrete. Journal of Wuhan University of Technology, 31(7) (2009), pp.84-87.

[4] Z.L. Chen: Influence of Fly Ash on Interior Relative Humidity of Concrete, Fly ash comprehensive utilization, 5 (2013), pp.32-36.

[5] Y. Yu, Z.W. Jiang: Effects of Moisture Diffusion and Self-Desiccation on the Early-Age Concrete's Internal Relative Humidity. Research and Application of Building Materials, 8 (2) (2009), pp.8-10.

[6] J. Kwasny, M. Sonebi , S.E. Taylor, et. al.: Influence of the Type of Coarse Lightweight Aggregate on Properties of Semilightweight Self-Consolidating Concrete, Journal of Materials in Civil engineering, 24 (12) (2012), pp.1474-1483.

DOI: 10.1061/(asce)mt.1943-5533.0000527

[7] X.X. Wang, X.D. Shen: Experimental Study on Strength of Lightweight Aggregate Concrete with Different Contents of Fly Ash, Bulletin of the Chinese Ceramic Society, 30 (1) (2011), pp.70-73.

[8] J.P. Behera, B.D. Nayak: Light weight concrete with sintered fly ash aggregate: A study on partial replacement to normal granite aggregate, Journal of the Institute of Engineers, India: Civil engineering Division, 85 (11) 2004), pp.84-87.