Study On The Influence Of The Character Of Slag-cement System On The Performance In The Early Age

The slag powder had been widely used as the additive in the cement and concrete. The preparation technology had changed from mixed grind to separate grind of the slag and cement. The separate grind of slag not only could improved the slag finesse but also made it possible to product it cosmically and recycling. But new problems appear in the application of the new method, such as the improvement of water requirement in fresh paste, and drop the early strength of cement stone. So emphases of the paper were discussed the relationship between the particle group characters of slag cement and the performance in the early day.The study adopts four token methods: specific surface, packing density, uniformity coefficient and fractal dimension, and used these methods to describe the finesse and particle distribution of the slag cement particle group. Adopt relative density of fresh paste, water consumption of standard consistence and fluidity to reflect the water requirement of fresh paste together. Fresh paste keeps the same water cement ratios in study work. The mainly results of the investigation were list as follow:Fixed the water cement ratio, the packing water reduced with the increasing of the slag and cement particle's packing density, but rewrap water is increased at the same time. It can improve fluidity of slag cement, and slow the increasing of the water requirement which caused by improvement of the slag's specific surface. Slag was play not only an role of physical filling effect but also an role of chemical effect in slag cement. So there is no notable relationship between the powder's packing density and the strength of slag cement stone.Keep the same ratio of slag and cement. When the specific surface of slag is the same, the water requirement of slag cement reduced and the relative density of freshpaste increased with the increasing of uniformity coefficient. It can optimist the pore structure and improve the early strength of the slag cement stone. Two conclusions can be drawn from the analysis of uniformity coefficient and powder's packing density: the slag's uniformity coefficient mainly affect on compressive strength of slag cement in 3 day;the improvement of the powder's packing density is propitious to increase the strength of cement stone in 28 day.When the specific surface is difference, the fresh paste relatively density improved with the increasing of slag cement powder's fractal dimension. When the percent of slag is more than 50%, the increasing trend of slag cement's strength is becoming more and more obviously with the increasing of the fractal dimension of slag powder.In addition, it has a certain relationship between the fractal dimension of slag and the activation of pozzolanic activity of slag in cement. It can be drawn from the microstructure image of SEM in 3 day: when the slag fractal dimension is more than 2.47, the content of C-S-H and AFt increased obviously of cement stone in early day, the early strength of slag cement improved rapidly at the same time.