Klun Martin, Bosiljkov Vlatko, Bokan-Bosiljkov Violeta
Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, SI-1000 Ljubljana, Slovenia.
Materials (Basel). 2021 Mar 23;14(6):1569. doi: 10.3390/ma14061569.
Microstructure development of concrete, mortar, and paste scale of cement-based material (CBM) during the early hydration stage has a significant impact on CBM's physical, mechanical, and durability characteristics at the high maturity state. The research was carried out using compositions with increased autogenous shrinkage and extended early age period, proposed within the RRT programme of the COST Action TU1404. The electrical conductivity method, used to follow the solidification process of CBM, is capable of determining the initial and final setting time, and the end of the solidification process acceleration stage for the paste and mortar scale. Simultaneous ultrasonic P- and S-wave transmission measurements revealed that the ratio of velocities / is highly dependent on the presence of aggregates-it is considerably higher for the paste scale compared to the mortar and concrete scale. The deviation from the otherwise roughly constant ratio / for each scale may indicate cracks in the material. The non-linear correlation between the dynamic and static elastic moduli valid over the three scales was confirmed. Additionally, it was found that the static E-modulus correlates very well with the square of the and that the is highly correlated to the cube compressive strength-but a separate trendline exists for each CBM scale.
水泥基材料（CBM）在早期水化阶段的微观结构发展对其在高成熟度状态下的物理、力学和耐久性特性有重大影响。该研究采用了在COST行动TU1404的RRT计划中提出的具有增加的自收缩和延长早期龄期的组合物进行。用于跟踪CBM固化过程的电导率方法能够确定初凝和终凝时间，以及浆体和砂浆尺度固化过程加速阶段的结束。同时进行的超声波P波和S波传输测量表明，速度比 / 高度依赖于骨料的存在——与砂浆和混凝土尺度相比，浆体尺度的该比值要高得多。每个尺度与大致恒定的比值 / 的偏差可能表明材料中存在裂缝。证实了在三个尺度上动态和静态弹性模量之间的非线性相关性。此外，发现静态弹性模量E与 的平方相关性非常好，并且 与立方体抗压强度高度相关——但每个CBM尺度都存在单独的趋势线。
