Leaching Behaviors of Heavy Metals from Mortar in Various Types of Solutions

摘要

Reduction of municipal wastes is important,and one of the probable solutions is to utilize by-products and wastes such as blast furnace slag and incinerated ash in eco-concrete.However,municipal wastes may contain heavy metals,and it is well known that heavy metal ions can be easily adsorbed on cement hydrates.On the other hand,it is also found that adsorbed heavy metal ions can be easily leached in the presence of calcium chloride.In the present study,the leaching behavior of heavy metal ions from mortar specimens immersed in various types of solutions was investigated.The results show that the leaching amount of the lead ions from the specimens immersed in CaCl2 solution was three times as large as that in the other solutions.However,the difference in the pore volume of the specimens after immersion between types of solutions was not observed.Besides,it is also found that in the case of the specimen with a water cement materials ratio of 0.40,the pore structures of mortar specimens were relatively denser and the pH value of the solution was lower compared with the case of the specimen with a water cement materials ratio of 0.55.This can result in smaller leaching amounts of heavy metals.