Analysis on Dynamic Mechanical Properties and Surface Micro-Topography of Alkali-Activated Concrete under Different Temperatures

In this paper, with water glass as alkali activator, slag and class F fly-ash based cementing material is mixed to prepare alkali-activated concrete. The dynamic mechanical property and surface micro-topography under different temperature of -50 degrees C-140 degrees C was evaluated by using dynamic mechanical analyzer (DMA+1000) and ESEM technology. DMA results show that when the ambient temperature changes from 28 degrees C to 140 degrees C, the rigidity of alkali-activated concrete increases, but the elastic deformation ability decreases; the temperature increment stimulates surface cracks of concrete to become wider and more, and increases the dissipation factor. When the ambient temperature changes from 28 degrees C to -50 degrees C, the storage modulus and rigidity of alkali-activated concrete increase first, and then decrease. ESEM test results show that the storage modulus will increase, and the dissipation factor will decrease at ordinary temperature. When the temperature increases, the surface cracks become larger, and the strength of material will decrease. Therefore, the material will be damaged, resulting in increased dissipation factor. When the temperature decreases, there is less cracks on the surface of alkali-activated concrete.