Comparative Study on Chloride Binding Capacity of Cement-Fly Ash System and Cement-Ground Granulated Blast Furnace Slag System with Diethanol-Isopropanolamine

Abstract

Steel bar corrosion caused by chloride was one of the main forms of concrete deterioration. The promotion of chloride binding capacity of cementitious materials would hinder the chloride transport to the surface of steel bar, thereby alleviating the corrosion and mitigating the deterioration. A comparative study on binding capacity of chloride in cement-fly ash system (C-FA) and cement-ground granulated blast furnace slag system (C-GGBS) with diethanol-isopropanolamine (DEIPA) was investigated in this study. Chloride ions was introduced by adding NaCl in paste, and the chloride binding capacity of the paste samples at 7 d and 60 d was examined. The hydration process was discussed via the testing of hydration heat and compressive strength. The hydrates in hardened paste was characterized by X-ray Diffractometry (XRD), Thermo Gravimetric Analysis (TGA), and Scanning Electron Microscope (SEM). The effect of DEIPA on dissolution of aluminate phase and compressive strength was discussed as well. These results showed that DEIPA could facilitate the hydration of C-FA and C-GGBS system, and the promotion effect was higher in C-FA than that in C-GGBS. DEIPA also increased the binding capacity of chloride in C-FA and C-GGBS systems. One reason was the increased chemical binding, because DEIPA facilitated the dissolution of aluminate to benefit the formation of Friedel’s salt. Other reasons were the increased physical binding and migration resistance. By contrast, DEIPA presented greater ability to increase chloride binding capacity in C-FA system, because DEIPA showed stronger ability to expedite the dissolution of aluminate of FA than that of GGBS, which benefited the formation of FS, thereby promoting the chemical binding. Such results would give deep insight into using DEIPA as an additive in cement-based materials.

Influences of Friedel’s Salt Produced by CaO-Activated Titanium-Extracted Tailing Slag on Chloride Binding

“…The lamellar thickness was smaller than 0.2 μm and lamellas were clustered at pores in the solidified samples ( Figure 5 e–h) [ 50 ]. The development of lamellar crystals at pores optimized the pore structure, increased the solid capacity of solidified samples, formed retardation against liquid flowing among pores, and decreased leaching of chloride ions to some extent [ 51 , 52 ]. Moreover, it was conducive to the strength growth of solidified samples [ 53 , 54 ].…”

Special Issue on Silicate Solid Waste Recycling

“…At present, many researchers are focusing on this topic, and construction and building materials have been considered as the best way to reuse such an enormous amount of industry silicate solid wastes [ 1 ]. For instance, steel slag has been successfully used in pavement engineering [ 2 , 3 , 4 ], fly ash is widely reused as cementitious materials in concrete [ 5 , 6 , 7 ], and waste tire rubber can be reused to improve the rutting resistance of asphalt pavement [ 8 , 9 , 10 ]. Along with these developments, there are still many challenges that should be further discussed.…”

“…Research indicated that the setting time of cement could be significantly shortened due to the introduction of carbide slag, which can be widely used in special projects where a fast setting is required. Blast furnace slag, a by-product from iron production in blast furnaces, was granulated and reused to enhance the corrosion resistance of steel bar used in cement concrete [ 6 ]. The corrosion resistance of the cement-ground granulated blast furnace slag system and cement-fly ash system was compared by adding NaCl in the paste.…”