Study on Curing Effect of Free Calcium Ions in Concrete under Contact Corrosion Conditions
In order to study the rule of calcium ion precipitation in shotcrete mixed with silica fume and sodium silicate as admixtures under contact dissolution conditions,single mixed and double mixed concrete test blocks were prepared under different admixtures.A 30-day deionized water immersion test was carried out to test the changes in calcium ion concentration and pH value in the solution and study the contact corrosion process in combination with microscopic de-tection such as SEM.The results show that the dissolution amount of calcium ions in the single doped silica fume test block is significantly lower than that in the blank group under the condition of not changing water.The average total weight of dissolved calcium ions in the 3％,5％and 7％doping groups decreases by 73.29％,69.65％and 69.26％re-spectively compared with the blank group within 30 days under the condition of water change.After single addition of so-dium silicate,the dissolution amount of calcium ions in the sample with 3％dosage can also be significantly reduced without water change.The average total weight of dissolved calcium ions in 1％,3％and 5％dosage groups is 9.22％,20.53％and 29.96％less than that in the blank group within 30 days in the case of water change.After the addition of 3％silica fume and 5％sodium silicate,which have good curing effect,into concrete,the initial calcium ion concentra-tion of immersion solution is only 20～30 mg/L under the condition of not changing water.The free calcium ions in the solution are cleared to zero from about the 18th day.Compared with the blank group,the average total weight of dis-solved calcium ions in the double mixed test block in the case of water change decreases about 85％.
tunnel engineeringshotconcretecalcium carbonate crystallizationcalcium ion precipitationcontact corro-sion
万方数据
维普
