tailieunhanh - Báo cáo khoa học "ADIABATIC TEMPERATURE RISE AND REACTION RATE OF MASS STRUCTURE IN LOTTE CENTER HANOI PROJECT "

It is necessary for concrete structure with mass section to have a rational crack control plan based on analysis of thermal stress from hydration heat. Because mass concrete can cause crack to deteriorate durability of structure. So, this study reports two examples: one is a process to calculate an adiabatic temperature rise and a reaction rate for evaluate thermal stress. | ADIABATIC TEMPERATURE RISE AND REACTION RATE OF MASS STRUCTURE IN LOTTE CENTER HANOI PROJECT Dr. KIM KWANG KI Eng. HWANG IN GWAN Eng. KIM MYOUNG GUG Lotte E C Lotte Center Hanoi Project Abstract It is necessary for concrete structure with mass section to have a rational crack control plan based on analysis of thermal stress from hydration heat. Because mass concrete can cause crack to deteriorate durability of structure. So this study reports two examples one is a process to calculate an adiabatic temperature rise and a reaction rate for evaluate thermal stress. And the other is how to control quality of mass concrete with reducing internal restraining stress through finite analysis. As a result a thermal crack index is over and a curing time of mass-section foundation decreases within 18 days through minimizing binders in concrete and adjusting hydration heat and delay setting time between the former and the latter placed concrete. Keywords mass concrete hydration heat thermal crack finite element analysis temperature history 1. Introduction A tensile stress by hydration heat of concrete is a main factor to deteriorate durability of structure because it causes crack in concrete from initial time of hardening. Especially a volume change in surface of mass-section element is almost same by cooling from low temperature in the air while inside of volume expands by high temperature from accumulating hydration heat. That is difference between inside and surface of structure causes a thermal crack from occurring a restraining Adding more high strength concrete with much binder becomes a serious There are two ways to minimize a thermal crack of mass concrete One is a construction method such as pre-cooling and pipe-cooling and the other is to control material by adjusting binder to occurea low hydration temperature. And all the methods are essential to check analysis of a thermal stress repeatedly to evaluate thermal crack index for quality and .