Development of Method for Measuring Residual Expansion of Cores Taken from Concrete Structures Affected by ASR

本研究发展了一种早期判断混凝土残余膨胀率受ASR影响的加速试验方法。测量混凝土芯的残余膨胀的当前方法不对应于海水除冰盐等渗透混凝土并促进ASR的环境。因此，我们针对这一问题，研究了一种加速试验方法，即将混凝土芯浸泡在NaOH或NaCl溶液中。储存温度的影响在低浓度下，当储存温度过高时，ASR膨胀变小，而在高浓度下，ASR膨胀随储存温度的升高而增大.溶液种类和浓度对ASR膨胀的影响在低温下，当溶液浓度过高时，ASR膨胀变小，而在高温下，ASR膨胀随溶液浓度的升高而增大。浸泡在NaOH溶液中的岩心比浸泡在NaCl溶液中的岩心在早期产生更大的膨胀.初始碱含量对混凝土ASR膨胀的影响初始碱含量越高的芯材在NaOH溶液中浸泡前的ASR膨胀越大.由于ASR引起的混凝土劣化程度的影响对于浸泡在NaOH溶液中的混凝土，当混凝土的劣化在试验开始前已经进行得更多时，试验开始后芯的ASR膨胀变得更小.加速养护条件的建议根据本研究范围内的试验结果，提出了一种早期判断混凝土残余膨胀率的加速养护条件。

This study developed an accelerated test method to judge the residual expansivity of concrete affected by ASR at the early stage. The current method, which measures the residual expansion of the concrete core, does not correspond to environments where seawater deicing salts, etc. penetrate concrete and promote ASR. Therefore, we addressed this problem by examining an accelerated test method with which the concrete cores were immersed in an NaOH or NaCl solution.The following results were obtained:1. Effect of Storage TemperatureASR expansion became small when the storage temperature rose excessively in the low solution concentration, but it increased with rising storage temperature in the high solution concentration.2. Effects of Kind of Solution and its ConcentrationASR expansion became small when the solution concentration rose excessively at low storage temperature, but it increased with rising solution concentration at high storage temperature. The core immersed in the NaOH solution generated larger expansion at the early stage than the core in the NaCl solution.3. Effect of Initial Alkali Content of ConcreteASR expansion of the core with a higher initial alkali content before immersion in the NaOH solution was larger.4. Effect of Degree of Concrete Deterioration due to ASRFor the concrete immersed in the NaOH solution, when the deterioration of the concrete had progressed more before the start of the test, the ASR expansion of the core after the start of the test became smaller.5. Proposal of Accelerated Curing ConditionBased on the results obtained within the range of this study, an acclerated curing condition was proposed to judge the residual expansivity of concrete at the early stage.