以環氧樹脂補強受高溫破壞混凝土之強度變化

Abstract

鋼筋混凝土建物火災損壞範圍集中在表層，因此混凝土高溫火害後補強相當重要，在不同冷卻方式不同養護條件下，試以環氧樹脂補強，探討其殘餘強度及補強效果。 本研究探討以普通混凝土與高強度混凝土兩種材料，在加溫時承受兩種目標溫度（600℃、800℃），冷卻時以不同冷卻方式（急速冷卻及自然冷卻），兩種再養護方法（滯水再養護及空氣再養護）與不同再養護齡期（7、28、60、90天），分別以環氧樹脂補強後成效進行比較。 結果發現，目標溫度600℃的試體補強效果較800℃的試體佳，可讓試體達到原強度的七成以上，但目標溫度800℃的試體補強效果就不盡理想，而且高溫火害後再養護時間越長，由於混凝土之自癒性，使環氧樹脂難以以真空方試灌入裂縫，補強成效因而折減。

The strength of reinforce concrete buildings decreased after exposed to high temperatures. Most damages of concrete are on the surface only. It is important to repair the cracks in concrete. The effect different cooling methods and curing conditions were explored. The residual strength and repair effect were studied after repaired by epoxy. This study is devoted to investigate the effect of epoxy on strength increase of concrete after fired. The major experimental parameters include high temperatures (600℃, 800℃), cooling methods (natural cooling, rapid cooling), re-curing methods (air curing, water curing), re-curing times (7, 28, 60, 90 days), and the strength of concretes (280 kgf/cm2, 560 kgf/cm2). Results show that the epoxy restored the compressive strength of concrete after exposed 600℃ can be greater than 70%. But concrete can recover only 10% of its strength for specimens after exposed 800℃ temperature.