Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

Abstract

The adverse effects of the long term application of electrochemical chloride extraction on binding capacity of hydrated cement products are innegligible. In this study, the influences of electrochemical chloride extraction in the microstructural properties of hydrated cement products of cement pastes were investigated in paste specimens by using a modified migration cell that was conducted with the applied current density of 4.5 A/m 2 and synthesized pore solutions as electrolytes for 8 weeks. Three types of cement pastes were used with the water-to-binder ratio of 0.4 including ordinary Portland cement (OPC), fly ash cement (FC) and ground granulated blast furnace slag cement (SC) pastes. Chloride source was supplied by adding 1.5% sodium chloride. After extraction, the acid-soluble and water-soluble chloride contents significantly reduced. Portlandite content increased proportionally with the time of extraction in OPC and FC pastes although the contribution of calcium ions in transferring the current is negligible. Some unsteady gel phases was obtained after a short time the extraction was stopped. Furthermore, the alteration and decomposition of C-S-H were inevitable with different rates depending on the type of cement.

Đánh Giá Tính Khả Thi Của Phương Pháp Thúc Đẩy Ăn Mòn Cốt Thép Trong Kết Cấu Bê Tông Cốt Thép Bằng Dòng Điện

“…Hình 1 cho thấy tác động nghiêm trọng của môi trường biển đến ăn mòn cốt thép trong bê tông cốt thép. Do đó, vô số các nghiên cứu đã được thực hiện nhằm đánh giá tác động của môi trường clo đến kết cấu bê tông cốt thép nhằm tìm hiểu cơ chế ăn mòn cũng như đánh giá khả năng chịu lực còn lại của kết cấu tại những mức độ ăn mòn khác nhau [3][4][5][6][7][8][9]. Tuy nhiên, ăn mòn cốt thép trong bê tông là một quá trình lâu dài, có thể lên đến vài thập niên [1,10].…”

Experimental Examination of Electrical Characteristics for Portland Cement Mortar Frost Damage Evaluation

“…After curing of the epoxy resin for one week, the samples were dried in a vacuum desiccator for another week and kept drying until testing. The vacuum pressure was less than 0.08 MPa [46]. Because the adhesive properties of the conductive paste may be sensitive to elevated temperature, to avoid the detachment of electrode and mortar, instead of using oven drying, the vacuum drying method was used for the electrical tests.…”

Effect of Electrochemical Corrosion on the Properties of Modified Concrete

“…In Refs. [13][14][15][16][17], two main reasons were given for the development of defects: reinforcement corrosion due to direct current; and reinforcement corrosion due to stray currents.…”