Chemically Prestressed Precast Concrete Box Culvert with Expansive Additives

  • Park, Hong-Yong (Dept. of Civil & Environmental Eng., Myongji University, Yong-In) ;
  • Kim, Chul-Young (Dept. of Civil & Environmental Eng., Myongji University, Yong-In) ;
  • Park, Ik-Chang (Dept. of Civil Eng., Mokpo Maritime University, Mokpo) ;
  • Bae, Sang-Wook (Dept. of Civil & Environmental Eng., Myongji University, Yong-In) ;
  • Ryu, Jong-Hyun (Dept. of Civil & Environmental Eng., Myongji University, Yong-In)
  • 발행 : 2001.01.01

초록

Although portland cement concrete is one of the most universal construction materials, it has some disadvantage such as shrinkage, which is an inherent characteristic. Because of this shrinkage, combined with the low tensile strength of the material, cracks of varying sizes can be found in every reinforced concrete. To prevent this cracking, keeping the concrete in compression by mechanical prestress has been used. This study discusses application of expansive additives for concrete to improve the serviceability of precast concrete box culvert by inducing chemical prestress. For this purpose, both expansive concrete slabs and normal concrete slabs are tested to verify the effect of expansive additives. Then the failure tests of the fullscale precast box culverts were carried out and the critical aspects of the structural behavior were investigated. The result of the material testis shows that the optimal proportion of expansive additives is 13 percent of cement weight, and the properties of expansive concrete are the same as those of normal concrete in that proportion. Both the experimental cracking load and service load of the expansive concrete members are increased in comparison with those of the normal concrete, but the ultimate load is decreased slightly. In addition to the above results, the deformation of expansive concrete member is lets than that of normal concrete member, and permanent strain which results from cyclic load is decreased. It can be concluded that the use of expansive additives to induce chemical prestress in precast concrete box culvert greatly improves the serviceability.

키워드

참고문헌

  1. ACI Journal Prodeedings v.67 no.8 Expansive Cement Concrete Present State of Knowledge ACI Committee 223
  2. ACI Publication SP 38-18 Reinforced Concrete Pipe Made with Expansive Cement Pfeifer,D.W.;Perenchio,W.f.
  3. Korea Concrete Institute Journal Usage of CSA Expansive Additives for Concrete Lee,S.W.;Kim,N.H.
  4. Standard Specification for Concrete