Bewertung des Einflusses einer mechanisch induzierten Rissbildung auf den Verlauf der schädigenden AKR mit innovativen Prüftechniken

该项目第四部分的目的是通过基本试验来完成中、微观尺度数值模式的基础。重点是通过创新的测量技术对裂化和输送过程进行定量描述。研究范围包括对ASR损伤之前的机械诱导开裂的描述，对质量传输过程的分析，以及对由此产生的ASR诱导开裂的表征。在第一个资金期内，循环四点弯曲试验表明，在循环荷载作用下，梁的抗拉区混凝土退化明显减少。这是湿致残余应力的结果。出于这个原因，将考虑额外的测试制度。疲劳裂纹的间歇性张开和闭合对质量传输过程的影响将被更详细地研究。在第一个资助期内优化的X-Ray-3D-CT技术将用于路面混凝土经过各种损伤诱导程序后的三维表征。此外，还将比较、分析和评估顶部试验溶液循环加载后或滚轮试验后进入混凝土的钠和氯化物。在第一个供资期间，只有循环气候储存试验表明，疲劳导致混凝土开裂退化，从而增加钠和氯的渗入，导致更大的ASR破坏。冻融期对ASR的影响尚不清楚。在造成损害的过程中引入的碱的影响在雾室中检测不到。将使用替代聚集体来阐明这一影响。对改良路面混凝土的附加试验(用特殊试验水泥(Na2O当量：1.30M-%)替代道路水泥)应阐明疲劳引起的裂缝对ASR的作用，并将作为ASR损伤模型(TP3)验证的基础。在不同的湿法预处理路面混凝土(破损和未破损)上使用不同的测试溶液进行的附加吸力测试将完成测试程序，以全面验证数值模型。空间水分和离子传输将被同时分析，并与相关的裂缝系统相关联。在深度上具有不同钠分布的大型混凝土梁将被储存在引发ASR的气候中。这些试验将阐明随深度变化的非均匀ASR严重程度对变形的影响。垂直测量的变形和水分分布将构成开发和验证宏观模型(TP6)的基础。

The aim of part 4 of the project is to complete the basis for numerical models on meso and micro scale by fundamental tests. The focus is on the quantitative description of the cracking and transport processes by means of innovative measurement techniques. The research spectrum includes the de-scription of the mechanically induced cracking prior to ASR damage, the analyses of the mass transport processes and the characterization of the resulting ASR-induced cracking. During the first funding period, cyclic four-point bending tests with test solution on top showed that concrete degradation in the tensile zone of the cyclic loaded beam significantly decreased. This is a result of the hygric induced residual stress. For this reason an additional test regime will be considered. The influence of the intermittent opening and closing of fatigue induced cracks on the mass transport processes will be investigated in more detail. X-Ray-3D-CT techniques, which were optimized during the first funding period, will be used for three dimensional characterization of the road surface concrete after various damage inducing procedures. Additionally, sodium and chloride ingress into the concrete after cyclic loading with test solution on top or after rolling wheel test will be compared, analyzed and assessed. During the first funding period only the cyclic climate storage test revealed that fatigue induced cracking concrete degradation, and the resulting increased sodium and chloride ingression, led to greater ASR damage. The effect of the freeze thaw period on ASR was still unclear. The effect of the alkalis, introduced during the damage inducing procedures, was not detectable in the fog chamber. Alternative aggregates will be used to clarify this effect. Additional tests on a modified road surface concrete (substitution of road cement by special test cement (Na2Oequivalent: 1,30 M.-%)) shall clarify the role of the fatigue induced cracking on ASR and will be the basis for the validation of the ASR damage model (TP3). Additional suction tests using various test solutions on different hygric preconditioned road surface concretes (damaged and undamaged) will complete the test program for a comprehensive validation of the numerical model. The spatial moisture and ion transport will be analyzed simultaneously and correlated to the associated crack system. Large concrete beams with different sodium distributions over the depth will be stored in an ASR provoking climate. These tests will elucidate the influence of a heterogeneous ASR severity that varies with depth on the deformation. The deformation and the moisture distribution, measured vertically, will form the basis for the development and validation of a macroscopic model (TP6).