Electrolyte:            0.5M ~ 1.0M LiOH solution

Due to reactions on the anode (equations 2a, 2a’, 2b), the pH of solution around the anode will decrease. The acidification of electrolyte and formation of chlorine gas are considered to be undesirable. An acidic solution may attack the concrete and chlorine gas is toxic. Using alkaline electrolyte such as saturated calcium hydroxide solution or a sodium borate solution can prevent acid attack on concrete and chlorine gas formation. At pH above 7, practically no chlorine gas is formed as the reaction on the anode is predominated by reaction indicated by equation (2a’).

Summary

Conventional concrete is excellent in durability and mechanical properties but is a poor electrical conductor, especially under dry conditions. Durable concrete that is excellent in both mechanical and electrical conductivity properties may have important applications in the electrical, electronic, military and construction industry (e.g. for CP system, de-icing road from snow).

Conductive concrete may be defined as a cementitious composite which contains a certain amount of electronically conductivecomponents to attain stable and relatively high electrical conductivity. The principle behind it is the use of cement to bind together electrically conductive materials such as carbon fiber, graphite and 'coke breeze' - a cheap by-product of steel production - to make a continuous network of conducting pathway. The design formulation is based on the 'electrical percolation' principle by which the composite conductivity increases dramatically by several orders of magnitude when the content of the conductive phase reaches a critical 'threshold' value. Further increases in the conductive phase content boost composite conductivity only slightly. The design specifies an amount just over the threshold content, assuring high conductivity and mechanical strength as well as good mixing conditions.

Concrete bridge decks are prone to ice accumulation. The use of road salts and chemicals for deicing is cost effective but causes damage to concrete and corrosion of reinforcing steel in concrete bridge decks. This problem is a major concern to transportation officials and public works due to rapid degradation of existing concrete pavements and bridge decks. The use of insulation materials for ice control and electric or thermal heating for deicing have been attempted and met limited success. Based on the results of a transient heat transfer analysis, a thin conductive concrete overlay on a bridge deck has the potential to become a cost effective deicing method. When connected to a power source, heat is generated due to the electrical resistance in the cement admixture with metallic particles and steel fibers. Small-scale slab heating experiments have shown that an average power of about 520 W/m² (48 W/ft²) was generated by the conductive concrete to raise the slab temperature from -1.1^oC (30^oF) to 15.6^oC (60^oF) in 30 minutes. This power level is consistent with the successful deicing applications using electrical heating cited in the literature.