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Technique of Modelling for Rock Breakage by Blasting
Published in M.I. Petrosyan, Rock Breakage by Blasting, 2018
while the dynamic modulus of elasticity is expressed as () E=γ(1+μ)(1−2μ)Cp2(1−μ)
EEMS2015 organizing committee
Published in Yeping Wang, Jianhua Zhao, Advances in Energy, Environment and Materials Science, 2018
When dynamic and static modulus of elasticity is compared, the average value of EMSR has been found higher than the average of ES, and the aver- age deviation between EMSR and ES is 3.53%. One possible reason is that lumber is a kind of viscoe- lastic body instead of elastomer. Static modulus of elasticity, obtained from static three-points bend- ing methods which takes a longer testing time, usually contains the factor of viscosity strain. Dynamic modulus of elasticity, on the other hand, could ignore the viscosity strain as the testing time Elastic propertyEMSRESMin/GPa8.938.52Max/GPa18.0317.3Average/GPa12.7312.28Standard deviation2.452.64Variance6.006.97Variation coefficient/%19.2521.5
Film formation properties of asphalt emulsion under ambient temperature drying
Published in International Journal of Pavement Engineering, 2023
Jian Ouyang, Yan Meng, Sohrab Zarei, Hanwen Yang
The dynamic modulus is used to analyse the film formation properties of asphalt emulsion from the aspect of stiffness. As shown in Figure 2(a), the dynamic modulus test was performed by a parallel plate rheometer at a constant frequency of 10 Hz and a constant temperature of 25°C. The diameter of the used parallel plate is 25 mm, and the thickness of the tested specimen is 1 mm. Compared to the parallel plate with a diameter of 8 mm, the chosen parallel plate can make the specimen of emulsion residue with a smoother surface after water evaporation. To prepare the specimens for the dynamic modulus test, asphalt emulsion was poured into the plate moulds with a diameter of 25 mm and thickness of 1 mm, as shown in Figure 2(b). To reduce the adverse effect of water evaporation on the thickness of specimens, the original thickness of asphalt emulsion specimens in the plate moulds should be higher than 1 mm. The asphalt emulsion specimens in Figure 2(b) were dried and cured in a temperature-controlled environmental chamber at 25°C. The dynamic modulus development of emulsion specimens was monitored during the whole drying and curing process (about 10 days). Specifically, the dynamic modulus of the asphalt emulsion specimens was tested about once per hour when the drying time was between 4 and 10 h, then the dynamic modulus was tested once every one or two days. Every dynamic modulus test was performed with three repetitions.
Sustainable Interventions: Conservation of Old Timber Roof of Michelangelo’s Cloister in Diocletian’s Baths
Published in International Journal of Architectural Heritage, 2023
Silvia Santini, Carlo Baggio, Lorena Sguerri
The dynamic tests provide a simple and non-invasive method for estimating the mechanical characteristics of the structural timber, in particular its elastic properties, thanks to the relationship that links the dynamic modulus of elasticity to the fundamental vibration frequency or to the stress wave speed. In the first case, flexural or longitudinal vibrations are generated by hitting the timber element, and its response is recorded. The dynamic modulus is calculated by means of the fundamental vibration frequency of the specimen, its density, its geometrical characteristics, and the test mode. In the second case, the “time of flight” of a sonic or ultrasonic stress wave, produced by a hammer or a probe, is measured. Then, the dynamic modulus of elasticity is evaluated by the following relationship:
Evaluation of effects of soybean derived oil and aggregate petrology on the performance of asphalt mixes
Published in Road Materials and Pavement Design, 2022
Muhammad Akhtar Tarar, Ammad Hassan Khan, Zia ur Rehman
The addition of soybean oil in binders decreased the dynamic modulus of the mixes; however, the decrease in dynamic modulus varied between the lower and higher frequencies and temperatures. The dynamic modulus is lower at lower frequencies (higher temperatures) and higher at higher frequencies (lower temperature). The decrease in dynamic modulus due to the addition of soybean oil was also observed by other studies (Elkashef et al., 2017a; Podolsky et al., 2019). The difference between the dynamic modulus values of unmodified and soybean oil modified asphalt mixes is less at 4°C as compared to the 21°C and 37°C in the central zone. Similarly, the dynamic modulus values of unmodified and soybean oil modified asphalt mixes show less difference at –10°C while there is more difference in the dynamic modulus values at 54°C in the predicted values. At lower, middle and higher temperatures the unmodified asphalt mixes show higher stiffness as compared to the modified asphalt mixes. This result reveals that the soybean oil decreased the stiffness of asphalt mixes at all the temperatures however this difference in values is more prominent at a higher temperature. This inference also justified the significance effect of soybean oil on reducing the stiffness of asphalt mixes as explained in the statistical analysis section. Nia et al. (2019) also reported that the rejuvenated asphalt mixes show less dynamic modulus value than unmodified asphalt mixes at higher temperatures.