Hardening performance of reclaimed gypsums for stabilizing agent to improve soft clayey ground

  • Nozomu Kotake
  • Hiroaki Sano


For a prospective solution of effective recycling of gypsum board wastes, the present study was conducted to evaluate applicability of reclaimed gypsum as stabilizing agent for improvement of soft clayey ground. A series of unconfined compression tests and needle penetration tests were conducted to understand the fundamental properties of reclaimed gypsum and gypsum treated soils and the durability in water. An important finding was strength decrease in relation to mixing time of gypsum and soil. This may attribute to excessive mixing that caused breakage of the promptly hardened gypsum treated clay. In addition, from sounding and laboratory tests on the stabilized ground by shallow mixing method with different execution conditions, it was found that the strength of stabilized ground appeared in an early stage and that the hardening effect of cement that was used in combination with gypsum continued in a longer period. Regarding an environmental aspect, a specific amount of cement could have restrained leaching fluorine satisfactorily under the standard level in the field by adopting suitable mixing proportions based on the laboratory mixing test results. For practical application, the mixing procedure was a major factor of strength growth when hemihydrate gypsum was used to stabilize soft clayey ground.


Reclaimed gypsum Soil stabilization Stabilizing agent Needle penetration Field execution test 


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Copyright information

© Springer Japan KK 2017

Authors and Affiliations

  1. 1.Department of Civil Engineering, National Institute of TechnologyKagawa CollegeTakamatsuJapan
  2. 2.Department of Civil and Environmental Engineering, National Institute of TechnologyOita CollegeOitaJapan

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