混凝土中性化為限制鋼筋混凝土結構物使用年限的主要因素之一,大氣中的二氧化碳與混凝土中氫氧化鈣反應造成混凝土pH值降低,使得鋼筋失去檢性環境之保護進而提高鏽蝕之風險。 目前國內外對於混凝土中性化的預測及評估方法,多為基於中性化的理論模式或是中性化試驗的經驗模式,這些中性化預測式中,有許多參數影響中性化深度對時間之關係,而這些參數又因地制宜,故相關研究所提供的數據,是否能夠符合台灣本土環境與材料品質等諸多特性,有其探討之空間。 本文以過去學者所做中性化試驗之資料及預測公式,與本研究於實驗室中進行快速碳化實驗之數據做比較,選定水膠比、卜作嵐材料種類及取代水泥百分比、二氧化碳濃度、環境平均濕度、混凝土抗壓強度等為影響參數,利用理論模型搭配修正係數建構一個符合本土特性的混凝土中性化深度預測式。
Carbonation of concrete is the major time-limiting factor for the durability of reinforced concrete structures. The carbonation reaction between atmospheric CO2 and Ca(OH)2 of the concrete mass destroys the high pH environment of surrounding concrete which protects the steel bars of reinforced concrete from corrosion. Most of the concrete neutralization depth prediction and assessment methods are based on theoretical models or empirical formulas. There are several parameters affecting the relationship between neutralization depth and time in those predicting formulas, and these parameters depend on local conditions. Thus, to determine whether those prediction formulas are feasible for the environment and materials in Taiwan become an important issue. In this study, comparison of theoretical models and accelerated carbonation test conducted in laboratory was presented. Water-cement ratio, pozzolanic material types, replacement rate, carbon dioxide concentrations, humidity and compressive strength are selected as the parameters affecting the theoretical models. The purpose is by using these models combine correction factor to meet the characteristics of concrete neutralization depth prediction formula in Taiwan.