Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Estimation of Unconfined Compressive Strength (UCS) of Microfine Cement Grouted Sand

마이크로 시멘트로 그라우팅 된 모래의 일축압축강도 예측

  • Nam, Hongyeop (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Woojin (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Changho (Dept. of Marine and Civil Engrg., Chonnam National Univ.) ;
  • Choo, Hyunwook (Dept. of Civil Engrg., Kyung hee Univ.)
  • 남홍엽 (고려대학교 건축사회환경공학부) ;
  • 이우진 (고려대학교 건축사회환경공학부) ;
  • 이창호 (전남대학교 해양토목학과) ;
  • 추현욱 (경희대학교 사회기반시스템공학과)
  • Received : 2018.03.28
  • Accepted : 2018.06.20
  • Published : 2018.07.31
Download PDF
⟨ Previous Next ⟩

Abstract

The unconfined compressive strength (UCS) test through coring is widely used to determine the reinforcement effect of the ground with grouting. However, the UCS test through coring can disturb the ground, is expensive and takes a lot of time to prepare the specimen. In this study, the factors affecting UCS of microfine cement grouted sand are evaluated and an empirical equation of UCS of microfine grouted sand is suggested. It is observed that UCS increases linearly until 28 days, however, the increasing rate of strength decreases sharply after that 28 days. The W/C ratio is dominant factor influencing UCS and UCS increases exponentially with the decrease of water/cement (W/C) ratio. Also, UCS increases linearly with increasing the relative density ranging from 30% to 70% and with decreasing median particle size. However, in case of W/C ratio=1 and K6 ($D_{50}=0.47mm$), UCS is lower than that of K4 ($D_{50}=1.08mm$) and K5 ($D_{50}=0.80mm$) due to filtration effect. Based on the experimental results, the empirical equation of UCS of microfine cement grouted sand can be expressed as the function of median particle size ($D_{50}$), porosity (n) and W/C ratio.

그라우팅을 통한 지반의 보강효과를 판단하기 위한 방법으로 코어링(coring)을 통한 일축 압축실험이 널리 실시되고 있는 실정이다. 하지만 코어링 시 원지반이 교란될 뿐만 아니라 시공비가 비싸며, 그라우팅 된 모래의 시편 준비에 많은 시간이 소요된다는 문제점이 있다. 따라서 본 연구에서는 마이크로 시멘트로 그라우팅 된 모래의 일축압축강도에 영향을 미치는 인자들을 비교/분석하고 28일 일축압축강도 추정식을 제안하였다. 마이크로 시멘트로 그라우팅된 평균 입경이 서로 다른 인공 파쇄사 (K4, K5 및 K6)의 일축압축강도는 양생기간 28일까지 선형적으로 증가하였으나 28일을 기점으로 강도의 증가율이 급격히 하락하였다. 물/시멘트(W/C) 비는 그라우팅 된 모래의 일축압축강도에 가장 큰 영향 인자이며, 일축압축강도는 W/C가 감소함에 따라 비선형적으로 증가하였다. 또한 일축압축강도는 상대밀도가 높아질수록 선형적으로 증가하였으며, 모래의 입자크기가 작아질수록 증가하는 경향을 보였으나 W/C=1, 및 K6($D_{50}=0.47mm$) 모래의 경우 필터레이션에 의하여 K4($D_{50}=1.08mm$)와 K5($D_{50}=0.80mm$) 모래의 일축압축강도보다 낮은 경향을 보였다. 실험결과를 바탕으로 마이크로 시멘트로 그라우팅된 모래의 일축압축강도를 모래의 평균입경($D_{50}$), 간극률(n)과 물/시멘트(W/C) 비의 함수로 제안하였다.

Keywords

References

  1. Akbulut, S. and Saglamer, A. (2002), "Estimating the Groutability of Granular Soils: A New Approach", Tunnelling and underground space technology, Vol.17, No.4, pp.371-380. https://doi.org/10.1016/S0886-7798(02)00040-8
  2. ASTM C136 (2006), "Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates", West Conshohocken, PA.
  3. ASTM C1231 (2015), "Standard Practice for use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders", West Conshohocken, PA.
  4. ASTM C940 (2010), "Standard Test Method for Expansion and Bleeding of Freshly Mixed Grouts for Preplaced-aggregate Concrete in the Laboratory", West Conshohocken, PA.
  5. ASTM D2488 (2009), "Standard Practice for Description and Identification of Soils (visual-manual procedure)", West Conshohocken, PA.
  6. ASTM D4253 (2015), "Standard Test Method for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density", West Conshohocken, PA.
  7. ASTM D4254 (2015), "Standard Test Method for Maximum Index Density and Unit Weight of Soils using Vibratory Table", West Conshohocken, PA.
  8. ASTM D854 (2014), "Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer", West Conshohocken, PA.
  9. Avci, E. and Mollamahmutoglu, M. (2016), "UCS Properties of Superfine Cement-grouted sand", Journal of Materials in Civil Engineering, 28(12), 06016015. https://doi.org/10.1061/(ASCE)MT.1943-5533.0001659
  10. Bruce, D.A., Littlejohn, G.S., and Naudts, A. (1997), "Grouting Materials for Ground Treatment: A Practitioner's Guide", Grouting: Compaction, remediation and testing, Geotechnical Special Publication No.66, pp.306-334.
  11. BS EN 12715 (2000), "Execution of Special Geotechnical Work: Grouting, British Adopted European Standard", London, UK.
  12. Christopher, B.R., Atmatzidis, D., and Krizek, R.J. (1989), "Laboratory testing of chemically grouted sand", Geotechnical Testing Journal, Vol.12, No.2, pp.109-118 https://doi.org/10.1520/GTJ10685J
  13. Chun et al. (2000), "Physical Properties Variation of Grout Materials based on the Water to Cement Ratio and the Mixing Speed", Journal of Korean Geo-Environmental Society, Vol.1, No.1, pp. 87-96.
  14. Clough, G.W., Kuck, W.M., and Kasali, G. (1979), "Silicate-stabilized sands", Journal of Geotechnical and Geoenvironmental engineering, Vol.105, No.1, pp.65-82.
  15. Clough, G.W., Sitar, N., Bachus, R.C., and Rad, N.S. (1981), "Cemented Sands under Static Loading", Journal of Geotechnical and Geoenvironmental engineering, Vol.107, No.6 pp.799-817.
  16. Dano, C. and Hicher, P.-Y. (2002), "Evolution of Elastic Shear Modulus in Granular Materials Along Isotropic and Deviatoric Stress Paths", In 15th ASCE Engineering Mechanics Conference.
  17. Dano, C., Hicher, P.-Y., and Tailliez, S. (2004), "Engineering Properties of Grouted Sands", Journal of Geotechnical and Geoenvironmental engineering, Vol.130, No.3, pp.328-338. https://doi.org/10.1061/(ASCE)1090-0241(2004)130:3(328)
  18. De Paoli, B., Bosco, B., Granata, R., and Bruce, D. (1992), "Fundamental Observations on Cement based Grouts (1): Traditional Materials", Soil improvement and Geosynthetics, Vol.1, pp.486-499.
  19. Eklund, D. and Stille, H. (2008), "Penetrability due to Filtration Tendency of Cement-based Grouts", Tunnelling and Underground Space Technology, Vol.23, No.4, pp.389-398. https://doi.org/10.1016/j.tust.2007.06.011
  20. Gustin, E., Karim, U. F., and Brouwers, H. (2007), "Bleeding Characteristics for Viscous Cement and Cement-bentonite Grouts", Geotechnique, Vol.57, No.4, pp.391-395. https://doi.org/10.1680/geot.2007.57.4.391
  21. Ismail, M. A., Joer, H. A., Randolph, M. F., and Meritt, A. (2002), "Cementation of Porous Materials using Calcite", Geotechnique, Vol.52, No.5, pp.313-324. https://doi.org/10.1680/geot.52.5.313.38709
  22. Kaga, M. and Yonekura, R. (1991), "Estimation of Strength of Silicate Grouted Sand", Soils and foundations, Vol.31, No.3, pp. 43-59. https://doi.org/10.3208/sandf1972.31.3_43
  23. Markou, I. and Droudakis, A. (2013), "Factors Affecting Engineering Properties of Microfine Cement Grouted Sands", Geotechnical and Geological Engineering, Vol.31, No.4, pp.1041-1058. https://doi.org/10.1007/s10706-013-9631-9
  24. Mollamahmutoglu, M. and Yilmaz, Y. (2011), "Engineering Properties of Medium-to-fine Sands Injected with Microfine Cement Grout", Marine Georesources and Geotechnology, Vol.29, No.2, pp.95-109. https://doi.org/10.1080/1064119X.2010.517715
  25. Mutman, U. and Kavak, A. (2011), "Improvement of Granular Soils by Low Pressure Grouting", International Journal of Physical Sciences, Vol.6, No.17, pp.4311-4322.
  26. Ozgurel, H.G. and Vipulanandan, C. (2005), "Effect of Grain Size and Distribution on Permeability and Mechanical behavior of Acrylamide Grouted Sand", Journal of Geotechnical and Geoenvironmental engineering, Vol.131, No.12, pp.1457-1465. https://doi.org/10.1061/(ASCE)1090-0241(2005)131:12(1457)
  27. Pantazopoulos, I. and Atmatzidis, D. (2012), "Dynamic Properties of Microfine Cement Grouted Sands", Soil Dynamics and Earthquake Engineering, Vol.42, pp.17-31. https://doi.org/10.1016/j.soildyn.2012.05.017
  28. Perret, S., Palardy, D., and Ballivy, G. (2000), "Rheological behavior and Setting Time of Microfine Cement-based Grouts", Materials Journal, Vol.97, No.4, pp.472-478.
  29. Henn, R. W., Association, Amerian Undergound Construction (2003), "AUA Guidelines for Backfilling and Contact Grouting of Tunnels and Shafts", Thomas Telford
  30. Schwarz, L.G. and Krizek, R.J. (2000), "Evolving Morphology of Early Age Microfine Cement Grout. In Advances in Grouting and Ground Modification", Advance in grouting and Grouting and Ground Modification, Vol.292, pp.181-199.
  31. Sayehvand, S. and B. Kalantari (2012), "Use of Grouting Method to Improve Soil Stability Against Liquefaction-A Review", Electronic Journal of Geotechnical Engineering, Vol.17, pp.1559-1566.
  32. Sunitsakul, J., Sawatparnich, A., and Sawangsuriya, A. (2012), "Prediction of Unconfined Compressive Strength of Soil-cement at 7 Days", Geotechnical and Geological Engineering, Vol.30, No.1, pp.263-268. https://doi.org/10.1007/s10706-011-9460-7
  33. Vaid, Y.P. and Nequssey, D. (1984), "Relative Density of Air and Water Pluviated Sand", Soil and foundation, Vol.24, No.2, pp. 101-105. https://doi.org/10.3208/sandf1972.24.2_101
  34. Warner, J. (2003), "Soil Solidification with Ultrafine Cement Grout", In Grouting and Ground Treatment, pp.1360-1371.
  35. Yoon, J. and El Mohtar, C.S. (2014), "Groutability of Granular Soils Using Bentonite Grout based on Filtration Model", Transport in porous media, Vol.102, No.3, pp.365-385. https://doi.org/10.1007/s11242-014-0279-6
  36. Zebovitz, S., Krizek, R., and Atmatzidis, D. (1989), "Injection of Fine Sands with Very Fine Cement Grout", Journal of geotechnical engineering, Vol.115, No.12, pp.1717-1733. https://doi.org/10.1061/(ASCE)0733-9410(1989)115:12(1717)