DOI QR코드

DOI QR Code

Hydration, Strength and pH Properties of Porous Concrete Using Rice Husk Ash

  • Kim, Young-Ik (Institute of Agricultural Science, Chungnam National University) ;
  • Sung, Chan-Yong (Division of Bio-Resources Engineering, College of Agriculture and Life Science, Chungnam National University)
  • Published : 2007.05.31

Abstract

This study was performed to evaluate void ratio, compressive and flexural strengths, and pH properties according to the content ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with content of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ of rice husk ash. In the XRD test, cement mortar with a 5% rice husk ash for the weight of cement registered a higher peak point of approximately $2{\theta}=20{\sim}25^{\circ}$ compared to cement mortar without rice husk ash. According to the results of the XRD and SEM tests, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with rice husk ash decreased with increasing content ratio of rice husk ash. In addition, the void ratio of porous concrete with rice husk ash decreased compared to porous concrete without rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% content ratio of rice husk ash slightly increased compared to concrete without rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. However, the pH value was nearly the same regardless of neutral treatment time in 28 curing days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels (less than 9.5) in all mixtures for planting at 28 curing days.

References

  1. Benz. D. P. and E. J. Garboczi., 1992, Modelling the leaching of calcium hydroxide from cement paste : effects on pore space percolation and diffusivity, Matends and Structures 25 : 523-533 https://doi.org/10.1007/BF02472448
  2. Boateng, A. A and D. A. Skeete., 1990, Incineration of rice hull for use as a cementitious material : The Guyana Experience, Cement and Concrete Research 20(5) : 795-802 https://doi.org/10.1016/0008-8846(90)90013-N
  3. Brandt. A. M., 1995, Cement-based composites: materials, mechanical properties and performance, E & FN Spon : 66
  4. Georgescu, Maria and Badanoiu, Alina., 1997, Hydration process in 3CaO. $SiO_2$-silica fume mixtures, Cement & Concrete Composites 19(4) : 295-300 https://doi.org/10.1016/S0958-9465(97)00021-8
  5. Isaia. G. C., A. L. G. Gastaldini., and R. Morases., 2003, Physical and pozzolanic action of mineral additions on the mechanical strength of high-performance concrete, Cement & Concrete Composites 25 : 69-76 https://doi.org/10.1016/S0958-9465(01)00057-9
  6. Julian Salas, Marina Alvarez and Janer Veras., 1986, Lightweight insulating concretes with rice husk, The International Jomal of Cement Composites and Lightweight Concrete 8(3) :171-180 https://doi.org/10.1016/0262-5075(86)90038-2
  7. Malhotra, V. M., 1976, No-fines concrete-its properties and applications, state of art report, ACI Journal 73(11) : 628-644
  8. Mehta, P. K and K. J. Folliard., 1992, Rcehuskash, a uniques supplementary cementing material, advances in concrete technology, CANMET Publication : 407-432
  9. Moayad N, Alkhalaf and Hana A. Yousift., 1984, Use of rice husk ash in concrete, The Intemational Journal of Cement Composites and Lightweight Concrete 6(4) : 263-275 https://doi.org/10.1016/0262-5075(84)90021-6
  10. Moayad N, Alkhalaf and A. Y. Halbod., 1986, Compactibility of no-fines concrete, The International Journal of Cement Composites and Lightweight Concrete 8(10) : 45-50 https://doi.org/10.1016/0262-5075(86)90023-0
  11. Park, Kwang Su and Lee, Joon Gu., 1999, A study on manufacturing durable precast concrete products with rice husk ash, Rural research institute of korea nual conmunity and mculture corporation
  12. Swamy. R. N., 1986, Cement replacement materials(concrete technology and design), Surrey University Press 3 : 171 - 196