Study on Cement Seed Effect of Nano-ettringite Synthesized by Solution Method
In order to study the seeding effect of ettringite crystals in the hydration of Portland cement,ettringite crystals in nanoscaled diameter were synthesized by a method of solution reaction,of which aluminum sulfate and calcium nitrate were employed as the reactants,and sodium hydroxide was used to adjust the pH value.After the microstruactural characterization by means of Zeta potential,X-ray diffraction(XRD),and scanning electron microscope(SEM),the nanoscaled ettringite seed in designed content were introduced into Portland cement mortar with different water/cement ratio to explore the influence of such ettringite crystal seed to the setting time and mechanical strength of Portland cement.The experimental results showed that the ettringite crystal seed synthesized by the method of solution reaction synthesis method was featured out with nanoscaled diameter,high degree of crystallinity,and high purity,which could make it be evenly dispersed in water with the aids of polycarboxylate water reducer,and thus significantly improve the early strength of cement mortar.By making use of the ettringite crystal seed at an optimized content of 0.3%,the compressive strengths of cement mortar at the age of 1 d and 3 d were improved by 15%and 8%,respectively.In the meanwhile,it was found that the initial setting time was elongated due to the involvement of ettringite crystal seed,while the final setting time was shortened to a certain extent simultaneously,and thus the initial-final setting time difference of cement was shortened.
NETL
NSTL
万方数据
