Engineering

Thermogravimetric analysis

Permeability (electromagnetism)

Materials science

Biochemistry

Durability

Silicate

Calcium silicate hydrate

Chemical engineering

Mortar

Organic chemistry

Membrane

Portland cement

Cement

Composite material

Chemistry

Scanning electron microscope

Casting

Fourier transform infrared spectroscopy

Hydrate

Compressive strength

Construction and Building Materials

Many of the degradation problems of concrete can be attributed to the weak surface layer. Surface treatment of concrete has been proven a simple and effective method to enhance the durability of concrete. In the present study, two series of portland cement mortar specimens with w/c ratios of 0.4 and 0.3 were prepared. CO2 treatment was applied to he mortars 24 h after casting. The results indicated that CO2 treatment resulted a carbonated a layer of less than 1.6 mm in thickness, slightly increased compressive strength, but significantly reduced the water permeability, water-vapor transmission and chloride migration of the mortars. Environmental Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR) Spectroscopy and thermogravimetric analysis (TGA) results indicated that calcium silicate hydrate with low Ca/Si ratio and CaCO3 were the products in the carbonated surface layer.

Effects of CO2 surface treatment on strength and permeability of one-day-aged cement mortar