Study On The Relationship Of Workability And Rheological Properties Of Slurry With Low Water-binder Ratio And Its Influencing Factors

Compared with the research on workability and rheological properties of common concrete,the study on cementitious material slurry with low water-binder or W/B ratio used in UHPC is lack at present.What’s more,the relationship between the workability and rheological properties of cementitious material slurry with low W/B ratio is not clear.So the rthogonal test and the single factor variable test were designed to study the effects of W/B,substituted rate of cement by fly ash microsphere and dosage of silica fume on the workability and rheological properties of cementitious material slurry with low W/B ratio.In the meanwhile,the theory of film thickness on particles was introduced,and the relationship between the workability and rheological properties based on film thickness on particles was established.In summary,the main researches and conclusions of this article include the following four parts:(1)The rthogonal test was designed to study the effects of W/B,substituted rate of cement by fly ash microsphere and dosage of silica fume on the workability,rheological properties and the relationship between them of paste with low W/B ratio in the second chapter.The results are as following: 1)The substituted rate of cement by fly ash microsphere is the main factor that affects the workability and rheological properties of paste followed by W/B ratio and dosage of silica fume in turn;substituted rate of cement by fly ash microsphere and W/B mainly affect the consistency coefficient,while dosage of silica fume mainly affects the yield stress of paste.2)Thickening of WFT can reduce the consistency coefficient and improve the flow spread of the paste,and the change of the dosage of fly ash microsphere will make the WFT-flow spread and WFTconsistency coefficient change significantly.3)The comprehensive balance method was used to obtain the optimal mix design of paste.For the raw materials used in this paper,the optimal mix design is W/B of 0.2,substituted rate of cement by fly ash microsphere of 40% and the dosage of silica fume of 8%.(2)The rthogonal test was designed to study the effects of W/B,substituted rate of cement by fly ash microsphere and dosage of silica fume on the workability and rheological properties the relationship between them of mortar with low W/B ratio in the third chapter.The results are as following: 1)The increase of W/B ratio and the substitution rate of cement by fly ash microsphere enhances PFT,and thickening of PFT can reduce the consistency coefficient and improve the flow spread.2)W/B ratio is the main factor that affects the workability and rheological properties of mortar followed by the substitution rate of cement by fly ash microsphere and dosage of silica fume in turn.(3)The single factor variable test was proceeded to mainly study the effects of fly ash microsphere on the workability and rheological properties of paste with low W/B ratio.The main researches and conclusions of the forth chapter include the following two parts: 1)The change rule of the workability and rheological properties of paste containing different proportions of fly ash microsphere has been clear: under the same W/B and the dosage of silica fume,with the substituted rate of cement by fly ash microsphere increasing,the flow spread increases and the increase rate slows down;the consistency coefficient decreases and the decline rate slows down;the yield stress increases,and the shear thickening increases.In the meanwhile,WFT increases at first,and after more than 20%,the increase rate of samples with high dosage of silica fume becomes slower,while that of samples with less silica fume gradually decreases.2)The relationship between the workability and rheological properties of paste based on WFT was established.(4)The single factor variable test was proceeded to mainly study the effects of fly ash microsphere on the workability and rheological properties of mortar with low W/B ratio.The main researches and conclusions of the fifth chapter include the following two parts: 1)The change rule of the workability and rheological properties of paste containing different proportions of fly ash microsphere has been clear: under the same W/B and the dosage of silica fume,with the substituted rate of cement by fly ash microsphere increasing,the flow spread and PFT increases;the consistency coefficient and yield stress decreases;the shear thickening behavior changed into shear thinning behavior.2)The relationship between the workability and rheological properties of mortar based on PFT was established.