Crack Prediction Model for Concrete Affected by Reinforcement Corrosion

The purpose of this study was to develop an analytical model to predict the time required for cracking of concrete due to corrosion of the iron reinforcement. The concrete and cement specimens used for this study were batched with cover material ranging from 0.75 to 1.3 in (1.91 to 3.30 cm). The extent of cover material was not formulated into the model under the assumption that crack initiation would tend to produce visible cracking within a relatively short time period. The model was derived using both Hooke’s Law and the volume expansion induced by the corrosion oxides. Correlation achieved with specimen cracking data from the literature was relatively good with a 95% level of confidence. This model presents a key benefit to facility and infrastructure managers by enabling them to plan the time when corrosion mitigating actions are required. It also provides a significant convenience as the condition of the concrete structure or its environment changes over time. The only parameter that needs to be updated over time is the corrosion rate measurement. This single parameter captures the most influential impact that stems from several other parameters which tend to be required in models that are more mechanistically definitive.

白江河林场天然与长期排水泥炭沼泽表层泥炭和积水中可溶性有机碳特征的比较

为了比较天然与长期排水泥炭沼泽表层泥炭和积水中可溶性有机碳特征,于2018年6~10月,在长白山区白江河天然和长期排水泥炭沼泽中,采集表层(0~10 cm深度)泥炭样品和积水样品,分别测定其可溶性有机碳含量、光谱指标和分子化合物组成,比较天然和长期排水泥炭沼泽表层泥炭样品和积水样品中可溶性有机碳的特征。研究结果表明,在植物凋落季(9~10月),与天然泥炭沼泽相比,长期排水泥炭沼泽表层泥炭中的可溶性有机碳含量偏小,其中,类蛋白质化合物含量所占比例偏小,类木质素化合物和芳香烃化合物含量所占比例偏大,长期排水泥炭沼泽表层泥炭中可溶性有机碳的稳定性较高;7月和8月,天然泥炭沼泽积水中可溶性有机碳含量显著偏大,其它时间长期排水泥炭沼泽积水中可溶性有机碳含量显著偏大;与天然泥炭沼泽相比,长期排水泥炭沼泽排水沟水中的类蛋白质化合物含量所占比例偏大,类木质素化合物和多糖类化合物含量所占比例偏小,长期排水泥炭沼泽排水沟水中的可溶性有机碳更易分解。