Determination of mortar setting times using shear wave velocity evolution curves measured by the bender element technique

作者：Zhu, J.; Cao, J. N.; Bate, B.^*; Khayat, K. H.

来源：Cement and Concrete Research, 2018, 106: 1-11.

DOI：10.1016/j.cemconres.2018.01.013

• Mortar
• Early age
• Shear wave velocity
• Initial setting time
• Final setting time
• Bender element

Although identified as a good indicator to characterize freshly cast cementitious materials, shear wave velocity (V-s) alone has not been used successfully to determine the initial and final setting times (t(i) and t(f)). The challenge originates from the large V, range that can vary from < 50 m/s to > 2000 m/s for cementitious materials at early age (typically < 24 h). To overcome these challenges, modifications to traditional bender element and to specimen geometry were made to obtain V-s versus time (V-s(t)) curves of six early age mortars at different water-to cement ratios, some with chemical admixtures. Derivative methods were then proposed to obtain t(i) and t(r). The peak time (t(peak)') in the first-order derivative of V-s(t) curves correlate well to the final setting time (R-2 = 0.979), while the peak time (t(peak)") of the second-order derivative of V-s(t) curves correspond well to the initial setting time (R-2 = 0.950).

• 出版日期2018-4
• 单位浙江大学