Effect Of Nano C-S-H-PCE On Early Hydration Of Cement And Microstructure Evolution

In the country to promote the special needs of prefabricated buildings and emergency repair and reinforcement projects,a highly efficient nanocomposite nanoC-S-H-PCE came into being.nano-C-S-H-PCE,as a new type of nanocomposite,can effectively improve the early hydration performance of cement,improve the production efficiency of concrete components,improve the construction progress of prefabricated buildings,but also speed up the progress of emergency repair projects to enable it to quickly recover.nano-C-S-H-PCE early strength agent,as a nano-modified material,has a direct influence on the hydration behavior and microstructure formation of early-age cement,thus affecting the workability,mechanical properties and durability of cement slurry.Therefore,it is of great significance to explore the nano-C-S-H-PCE for the hydration process regulation,microstructure evolution and performance research of early cement.In this paper,the influence of nano-C-S-H-PCE on early cement hydration process was explored,the mechanism of nano-C-S-H-PCE on cement hydration was clarified,and the hydration products and microstructure of cement slurry were characterized,and the influence of nano-C-S-H-PCE on early cement hydration products and microstructure was proved.The main research results of this paper are as follows:（1）Nano-C-S-H-PCE accelerates the hydration process of cementThe influence of nano-C-S-H-PCE on cement hydration process was studied by setting time,electrical conductivity,pH test and mortar strength test.The results show that the setting time of cement slurry decreases with the increase of nano-C-S-H-PCE early strength agent.The conductivity increases gradually with the increase of nano C-S-H-PCE,and the ion dissolution accelerates.The chemical binding water content increases with the increase of nano-C-S-H-PCE,and the nano-C-S-H-PCE improves the hydration degree of cement slurry.The influence of nano-C-S-H-PCE on the strength of cement mortar was studied through cement mortar strength test.The results showed that the addition of nano-C-S-H-PCE significantly increased the compressive strength of cement mortar.The above tests prove that nano-C-S-H-PCE has a certain acceleration effect on the hydration of cement slurry.（2）Nano-C-S-H-PCE accelerates the formation of cement hydration products and the formation of microstructureThe influence of nano-C-S-H-PCE on cement hydration product calcium hydroxide（CH）was investigated by thermogravimetric and X-ray diffraction experiments.The results show that nano-C-S-H-PCE accelerates the formation of CH,and its content increases with the increase of nano-C-S-H-PCE.The effect of nano-C-S-H-PCE on the polymerization degree of hydration product C-S-H gel was studied by ft-IR and solid-state NMR.The FTIR spectra showed that the peak-to-peak value of the stretching vibration of Si-O bond shifted to higher wave,and the peak intensity and peak area increased obviously with the increase of the amount of nano-C-S-H-PCE,indicating that the nano-C-S-H-PCE accelerated the polymerization of si-o tetrahedron.Solid state nuclear magnetic test proved that the addition of nano-C-S-H-PCE increased the average length of straight chain of C-S-H gel,and improved the degree of polymerization of silicon-oxygen tetrahedron in C-S-H gel.The above tests showed that the addition of nano-C-S-H-PCE promoted the formation of hydration product C-S-H gel,and its content increased with the increase of nano-C-S-H-PCE dosage.The change law of ultrasonic wave velocity of cement mortar was studied by ultrasonic test.The test results show that ultrasonic wave velocity of cement mortar increases with the increase of nano-C-S-H-PCE,which indicates that nano-C-S-H-PCE makes the density of cement mortar increase.Mercury injection test proves that the maximum pore size and cumulative pore volume of cement slurry decrease with the increase of nano-C-S-H-PCE,which further confirms that nano-C-S-H-PCE promotes the hydration process of cement slurry,which is consistent with the results of ultrasonic test.BET test proved that with the addition of nano-C-S-H-PCE,gel pores appeared continuously in the cement slurry,and the accumulated pore volume and the most pore size were continuously migrated to the pore,and the specific surface area was continuously increased,indicating that hydration products were increasing.SEM observed that the internal hydration products of cement slurry mixed with nano C-S-H-PCE were significantly more than that of cement slurry,and the hydration products became more and the internal structure became more dense.The test results were consistent with the strength of cement mortar.The above tests confirm that with the addition of nano C-S-H-PCE,the internal density of cement slurry keeps increasing and the hydration process accelerates.（3）Nano-C-S-H-PCE accelerates the hydration process and microstructure formation of cement mixed with mineral admixturesThe influence of nano-C-S-H-PCE on cement hydration process was studied by setting time,electrical conductivity and chemical binding water experiments.The results show that the setting time of cement slurry decreases with the increase of nano-C-S-H-PCE.The electrical conductivity increases with the increase of nano-C-S-H-PCE,and the ion dissolution of cement particles accelerates.The chemical binding water content increases with the increase of nano-C-S-H-PCE,and the nano-C-S-H-PCE improves the hydration degree of cement slurry.The influence of nano-C-S-H-PCE on the strength of cement mortar was studied through cement mortar strength test.The results showed that the addition of nano-C-S-H-PCE significantly increased the compressive strength of cement mortar.The above tests prove that nano-C-S-H-PCE has a certain acceleration effect on the hydration of cement slurry.The effect of nano-C-S-H-PCE early strength agent on the degree of gel polymerization of hydration product C-S-H was studied by FTIR.The results show that the peak-to-peak value of the stretching vibration of Si-O bond shifts to a higher wave number with the increase of the amount of nano-C-S-H-PCE,and the peak strength and peak area increase obviously.The nano-C-S-H-PCE accelerates the polymerization of Si-O tetrahedron.The change law of ultrasonic wave velocity of cement mortar was studied by ultrasonic testing test.The results showed that ultrasonic wave velocity of cement mortar increased with the increase of nano-C-S-H-PCE early strength agent,indicating that nano-C-S-H-PCE made the density of cement mortar increase.Mercury injection test proved that the maximum pore size and cumulative pore volume of cement slurry decreased with the increase of nano-C-S-H-PCE early strength agent,and confirmed that nano-C-S-H-PCE promoted the hydration process of cement paste,corresponding to the results of ultrasonic test.