【摘 要】
：
A microrheology analyzer (Rheolaser LAB6TM) was adapted to in-situ follow the development of the viscoelastic properties of fresh cement pastes (FCPs) by measuring the mean square displacement of ceme
【机 构】
：
Beijing Key Laboratory of Track Engineering, School of Civil Engineering, Beijing Jiaotong Universit
【出 处】
：
The 14th International Congress on the Chemistry of Cement (
论文部分内容阅读
A microrheology analyzer (Rheolaser LAB6TM) was adapted to in-situ follow the development of the viscoelastic properties of fresh cement pastes (FCPs) by measuring the mean square displacement of cement particles which gives an insight into the elastic and viscous properties of the material from a microstructural point of view.Various parameters including elastic index (EI), macroscopic viscosity index (MVI), storage modulus G, loss modulus G", and Maxwell parameters, microscopic viscosity η as well as elastic modulus G,were obtained to quantitatively analyze the viscoelastic properties of FCPs.Results indicate that these parameters show a progressive increase with elapsed time at first and then stay stable.The addition of superplasticizer significantly decreases the values of these parameters as well as their increasing rates with time.For cement pastes with high dosages of superplasticizer, these parameters start with a flat period followed by a slow increase with time, which results from the dispersing effects of superplasticizer on cement grains and the retarding effects of superplasticizer on cement hydration.At a given time, more remarkable effects of superplasticizer are observed at lower W/C.It is believed that EI and G are closely related to the dispersion degree of the solid particles in the cement paste, which contributes the most to the elastic property of the cement paste.The incorporation of superplasticizer evidently weakens the elastic feature of the fresh cement paste.
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