本文利用實驗探討混凝土延遲性鈣礬石形成的影響因子，實驗變因包括：水化早期的溫度(室溫、70˚C 及 85˚C)、高溫延時(12 小時、48 小時與 10 天)、粒料種類(反應性及非反應性粒料)及硫含量(2.46%及 5%)，量測及觀察項目包括：膨脹量、裂縫發展、顯微觀測及元素分析。本文定期量測試體膨脹量並紀錄裂縫發展歷程，此外，利用掃描式電子顯微鏡對延遲性鈣礬石之晶體及元素組成進行微觀分析。研究結果顯示，溫度高低是影響延遲性鈣礬石形成的關鍵；試體若在水化早期經歷高溫，約於 300~500 天後會發生明顯膨脹，且試體水化早期經歷溫度越高，後期膨脹量也越大。在高溫延時方面，試體於水化早期處於高溫環境越久，會使延遲性鈣礬石提早形成，試體提早發生膨脹。硫含量 5%的試體有明顯膨脹發生，2.46%的試體即使經過高溫也不會發生膨脹。在電子顯微鏡觀察下一般鈣礬石及延遲性鈣礬石之形貌及元素組成均極為類似，故難以加以區分；兩者最大的差異在於形成的位置，一般鈣礬石為水泥水化早期（約數天）的產物，故常散佈於水泥漿體中，而延遲性鈣礬石為水泥硬固後，經歷長時間（數百天或數年），緩慢地於孔隙及微裂縫中再次進行鈣礬石反應形成，將孔隙及微裂縫擴大，導致劣化，故延遲性鈣礬石多存在於孔隙及裂縫中，且常沿孔隙壁面及裂縫面生長。;This paper used some laboratory experimental tests to investigate the deterioration factors for delayed ettringite formation (DEF) in concrete, includes hydration temperatures (20˚C, 70˚C, and 85˚C), heating durations (12 hours, 48 hours and 10 days), aggregate types (reactive and Non-reactive), and sulfate contents (2.46% and 5%). The experiments observations included specimen expansions, crack propagations, and microanalyses (Scanning Electron Microscopy, SEM; Energy Dispersive Spectrometer, EDS). The results show that DEF could occur in high hydration temperature and high sulfate content environment; the expansion will rapidly increase in 300~500 days (concrete age), which had a positive correlation with hydration temperature; there was no DEF occurred in low sulfate contents (2.46%). For specimens were cured at long period high temperature heating duration, DEF will occur earlier than which were cured at short period high temperature heating duration. Until now, to identify “normal ettringite” and “delayed ettringite” in SEM and EDS analyses is difficult, but still could be determined by ettringite locations.
