| Nowadays, the workability of concrete, especially its fluidity, is payed more and more attention.Concrete’s fluidity is an important quota of concrete, which is an action of concrete mixture under theaction of gravity or mechanical vibrating force. Because of the fluidity, Concrete model can flow andbecome more symmetrical and denser. Concrete’s fluidity is directly related to the concrete’s construction,late strength and durability. On the other hand, because of the influence of spall in the concrete, the studyon the properties of concrete is very difficult. So more and more study begin to reserch concrete’s fluidity.However, mortar’s components is close to the concrete’s, so cement mortar can be regarded as a kind offine-aggregate concrete.Even if there are many kinds of experiments on the rheological properties of the cement mortar’sfluidity, with the development of new building admixture and materials, the traditional testing methodseems limitated, which can not reacte the cement mortar’s fluidity very well. Especially with thedevelopment of high-fluidity mortar, seeking better research methods on mortar’s fluidity is crucial.This article discusess mortar’s fluidity based on a L-type glass tube. When the measurement of theL-type glass tube is in a constant value, according to theory analysis, the study builds a mathematicalrelationship among the parameters of mortar’s fluidity. This paper deduces mortar’s two basic rheologicalparameter by measuring mortar’s flowing speed and eventually vertical length in the L-tube, and finallyreaches some main conclusions as follows:1.By mathematical analysis, theoretically, the study comes to a dicision about the two rheometerparameters of mortar’s fluidity, and then Calculates the two basic rheological parameters with a certaingeometry of L-tube.2. Water-cement ratio is the main factor that affects the mortar’s fluidity. With the increase ofwater-cement ratio, the slurry’s rheology is increasing, and the shear stress τ0and viscosity coefficient η iscorresponding smaller. Shear stress τ0and viscosity coefficient η changed linearly with the changing of thewater-cement ratio.3. Fly ash in the mortar can significantly improve its rheological properties. The study also finds that the mortar’s fluidity is best when the content of fly ash is30%. With the changing of the fly ash，the τ0’sandη’s changing is parabolic. On the other hand the study finds that furnace slag can improve of mortar’sfluidity when there is a little dosage (no more than10%), and then genenally, with dosage of furnace slagincreasing, the rheological properties is decreasing. This means that the higher the content of furnace slag,the lower the mortar’s rheological properties, and there is a linear change in value τ0andη. The article alsofinds that double mixture of fly ash and slag makes the mortar’s rheological properties lower than fly ash,but higher than furnace slag. The τ0andηhas linear change with the participation materials increasing.4. Glue powder can significantly reduce the mortar’s fluidity under a certain water-cement ratio, at thesame time, τ0and η is significantly improved. And with the glue powder’s content increasing, the rheologyof the slurry is becoming worse, and the theτ0and η are becoming higher. Mixing glue powder into themortar contained Fly ash or Slag, the study finds that glue powder can deteriorate the mortar’s fluidity. Andthen the study adds glue powder into the mortar with both Fly ash and Slag, finally finds that the adding ofpowder can reduce the rheological properties of the mortar. These mortar’s rheological properties isbetween the mortar’s only contained fly ash and the mortar’s only contained furnace slag. |
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