環氧樹脂補強火害後混凝土之參數研究

Abstract

混凝土受到高溫時，會有裂縫的產生，漿體也會產生分解，混凝土強度大幅度降低。 目前業界處理裂縫的作法。大都是使用打針貫注環氧樹脂的方法。如用水加以養護，混 凝土會有再水化的現象，可以揮復部份原有強度。於是合併上述兩種作法，利用含水份 較多之高滲透性環氧樹脂以高壓方式貫注受火害試體，以恢復受火害試體之抗壓強度。 影響混凝土強度最大的因子是火害溫度的高低，因此本計畫對於溫度的變數將採取 400oC 、500oC 、600oC 、700oC 及800oC 五種溫度進行試驗。混凝土強度受火害影響 的變數除了火害溫度以外，冷卻速率的影響也非常大，本計畫將執行急速降溫及慢速降 溫兩種方式。混凝土受火害後，其強度仍然會持續的降低，其開始恢復強度的時間點會 因所受火害溫度、再養護方法及冷卻方式有所不同，因此開始進行環氧樹脂貫注的時間 點也有可能影響補強的成效，本計畫對環氧樹脂貫注的時間點設定為7 天、14 天及21 天三個變數。高強度混凝土的火害行為與一般普通強度混凝土有所不同，因此擬使用 4000psi 及8000psi 兩種強度的混凝土。 本計畫之試體規畫為10 公分直徑20 公分長的圓柱試體，必須有參考樣品，因此必 須有未受火害參考組、環氧樹脂貫注前的參考組及在貫注環氧樹脂後28 天的試驗組等 三組試體，每一組使用三個試體之平均。

When concrete exposed elevated temperature，decomposition of cement and cracks occur in concrete induce the decrease at strength of concrete. The injection of epoxy was used in industry to treat the problem of cracks. The re-curing by water can make concrete re-hydration and re-gain part of the strength due to exposed to fire. Using injecting epoxy which contain more water into concrete will work to recover the strength. Major parameter to affect the strength lost of concrete at elevated temperature is the temperature which concrete exposed. The parameter of temperatures used in this project are 400oC、500oC、600oC、 700oC and 800oC . The cooling rate of concrete after exposing high temperature is important too. In this research both slow and rapid cooling rate will be adopted. Concrete continue to decrease its strength before recovering its strength by re-curing. The time begin to recover its strength depending on cooling rate, temperature exposed and re-curing approach. The Time to inject epoxy will scheduled to be 7 days, 14 days and 21 days. High strength concrete have different behavior at high temperature compared with normal strength concrete. 4000psi and 8000psi concrete will be used in this research. 10 cm diameter and 20 cm high concrete cylinder will be used in the test. The compressive strength before exposing high temperature will be used for reference. The compressive strength test will be executed for before and after the injection of epoxy. The average of three specimens will be used for each data,