Abstract
Building material samples were made by using a nonasbestos fiber-reinforced globular cement composite material treated with a high-velocity pneumatic double-stage impactor. The effects that the different mixing methods the modifying mechanism exerted on the process of changing specific surface area, the pore size distribution before and after freeze-thaw cyces of the building material, the improvement of the microstructure, the frost durability and the heightening of the strength were examined.
As the results, the following improvement in the characteristics was obtained. The correlation between the fractal dimension DF of the range of pore size of 0.01-1μm and frost damage property was obtained. It was found that the reduction of the minimum water/cement ratio at kneading and forming are feasible by the treatment of becoming globular. The lowering of DF and the improvement of the frost durability can be obtained.
In the system being treated with the process of becoming globular, the total pore volume decreased. The proportion of the pore volume in the zone of 0.05-1.0μm pore size which adjoins the zone of 0.01-0.05μm corresponding to the pores inside reinforcing fiber bundle was relatively large. Consequently, the channels for flowing water at the time of freezing were secured, and the improvement of the frost durability was obtained.
