Keywords and Phrases
Bender Element; Cementitious Material; Setting Time; Shear Wave Velocity
This study aims at using modified bender element (BE) method to monitor the shear wave velocity (Vs) of mortar at early-age and determine initial and final setting times with the Vs method. Modifications of the traditional BE method have been made to overcome the aggressive cementitious environment and eliminate electromagnetic coupling. BE has been successfully employed in mortar samples with and without admixtures to evaluate the evolution of Vs during the early age (first 24 hrs) of hydration. An energy approach method of determining the first arrival time of S-wave has been proposed. Pulse wave velocity test, penetration resistance test and calorimetry test were carried out to comprehensively evaluate the setting process. The evolutions of Young’s modulus E, shear modulus G, bulk modulus K, and Poisson’s ratio ν with time were then determined based on Vs, Vp and r measurements.
Log-normal distribution and soil-water characteristic curve (SWCC) were used to fit the Vs-time relationship. It was found that the time corresponding to the largest slope (i.e. maximum increasing rate) of the Vs curve corresponds to the final setting time. The initial setting time shows a linear relationship with the first inflection point and parameter a in SWCC equation. This proposed method of determining setting times with Vs had a high accuracy (R2=0.98). With the non-destructive nature and reliable results, bender element method of obtaining Vs and determining set times has a potential application in the cement industry.
Civil, Architectural and Environmental Engineering
M.S. in Civil Engineering
Missouri University of Science and Technology
ix, 50 pages
© 2015 Jianfeng Zhu, All rights reserved.
Thesis - Open Access
Electronic OCLC #
Zhu, Jianfeng, "Determination of setting times by shear wave velocity evolution in fresh mortar using bender element method" (2015). Masters Theses. 7702.