{"id":42952,"date":"2018-06-29T14:45:09","date_gmt":"2018-06-29T13:45:09","guid":{"rendered":"https:\/\/www.pbctoday.co.uk\/news\/?p=42952"},"modified":"2018-10-11T14:45:35","modified_gmt":"2018-10-11T13:45:35","slug":"corrosion-protection-of-reinforced-concrete","status":"publish","type":"post","link":"https:\/\/www.pbctoday.co.uk\/news\/building-control-news\/corrosion-protection-of-reinforced-concrete\/42952\/","title":{"rendered":"Corrosion protection of reinforced concrete"},"content":{"rendered":"

Cementaid<\/a> offer a look into how the Everdure CALTITE concrete stands the test of time when subjected to the harsh environment of the Fimiston open pit mine in Australia<\/h2>\n

The Fimiston open pit mine is the largest open pit gold mine in Australia. Located on the southeastern edge of Kalgoorlie-Boulder, approximately 600km east of Perth, the mine is managed by Kalgoorlie Consolidated Gold Mines (KCGM) and owned (50\/50) by Newmont Australia and Barrick Gold Corporation. Ore extracted is treated in two processing plants \u2013 the Fimiston plant and the Gidji Roaster plant. The need for increased production in the 1990\u2019s saw the Fimiston plant undergo a significant expansion with the installation of a new single large Sag Mill in 1994.<\/p>\n

Corrosion<\/h3>\n

The production of gold from ore at the Fimiston mine relies on the presence of freely available yet highly saline bore water which is used for plant processing, wash-down of equipment, road watering and dust suppression. Severely contaminated with chloride, sulphate and magnesium salts, the bore water is highly destructive to normal reinforced concrete<\/a>. Moreover, the salt and sulphate levels in the bore water at Fimiston are in the extreme range and produce an exceptionally severe\/corrosive service environment for reinforced concrete subject to daily wet\/dry cycling under the hot, windy conditions at Fimiston.<\/p>\n

Water analysis of the bore water used at Fimiston is as follows:<\/h3>\n\n\n\n\n\n
pH:\u00a0\u00a0\u00a0\u00a0 5.3 to 7.5<\/td>\nTDS:\u00a0 \u00a0158000-217000 mg\/l<\/td>\nCO3<\/sub>:\u00a0\u00a0\u00a0\u00a0 <0.3 mg\/l<\/td>\n<\/tr>\n
SO4<\/sub>:\u00a0\u00a0 8500-12000 mg\/l<\/td>\nCl-\u00a0 \u00a0 \u00a0 \u00a0 88000-122000 mg\/l<\/td>\nNa+\u00a0\u00a0\u00a0\u00a0\u00a0 51000-70000 mg\/l<\/td>\n<\/tr>\n
Ca++\u00a0 640-1050 mg\/l<\/td>\nMg++\u00a0\u00a0 6500-9000 mg\/l<\/td>\nK+\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 90 \u2013 435 mg\/l<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

The high chloride concentration promotes rapid penetration of the cover layer and premature corrosion of embedded reinforcement. The high levels of sulphate salts cause surface loss by physical salt scaling as well as two separate corrosion reactions which lead to denaturing and disintegration of the cement matrix itself:<\/p>\n