Study On The Effect Of Pan Fiber And Cellulose Fiber On The Properties Of Steel Slag Cement Cementitious Material

The chemical composition of steel slag is relatively complicated,and it contains gelling active substances such as dicalcium silicate and tricalcium silicate.Therefore,the application of steel slag in the field of building materials has great advantages.However,when a large amount of steel slag is used in building materials,the product has volume expansion and cracks,resulting in a rapid decline in its mechanical properties,thereby limiting the use of steel slag.In order to solve the problem of the decrease in mechanical properties and volume expansion of steel slag in the application,this paper starts from the rheological properties of the slurry,studies the rheological properties of the slurry after the steel slag is mixed,analyzes the reasons for the change,and uses polyacrylonitrile(PAN)fibers and cellulose fibers are used as reinforcing materials and mixed into steel slag samples to study the influence of fiber types and content on the mechanical properties and volume expansion rate of steel slag cement samples.After adding PAN fibers to the sample,the fibers are randomly distributed in the matrix,which can absorb the micro-stress inside the sample.Among them,the short fiber of 6mm can improve the performance of the sample more than the long fiber of 12mm.Moreover,adding short PAN fiber has a higher impact on the strength of samples 7d and 28d than that of sample 3d,indicating that the addition of short PAN fiber has an effect in the early and late stages,and when long PAN fiber is added,The impact on the 28d strength of the sample is better than the impact on the early strength,indicating that the effect of long fibers in the later period is more obvious.The 6mm PAN fiber shows the best performance when the content is 0.1%,and the 12mm PANfiber shows the best performance when the content is 0.5%.After preparing the sample with cellulose fiber,it is found that the compressive strength of the sample at 28d is as high as 50.31 MPa,and the flexural strength is 6.71 MPa.Compared with PAN fiber,the lifting effect is more obvious.The mechanical properties have the best effect.The expansion rate test samples were prepared with the optimal volume content of the two fibers to study the effect of fiber types on the volume expansion rate.The inhibition effect of the two PAN fibers on the expansion rate was lower than that of the cellulose fiber.In the early stage of hydration,there is not much hydration phase attached to the surface of the two fibers,and there are obvious gaps in the contact position between the fiber and the sample.As hydration progresses,in the later stage of hydration,it is clearly observed that a large number of hydration product phases grow on the fiber surface,which not only fills the gap between the fiber and the matrix,but also makes the stress better when subjected to external loads Focus on the fiber.At this time,the fiber can significantly improve the mechanical properties of the sample.