Is it true that there are ways to make concrete permanently poisonous to fungi and germs?

Permanent seems too much to expect. ACI Committee 212, in its "Guide for Use of Admixtures in Concrete," lists three materials which, when added in amounts in the range of 0.1 to 10 percent by weight of cement, inhibit the growth of fungi and bacteria:

  • polyhalogenated phenols
  • dieldrin emulsion
  • copper compounds

If more than 3 percent is added it may have an adverse effect on the strength of the concrete. Effectiveness is reported to be temporary, particularly that of the copper compounds.Organotin compounds have also been reported to inhibit growth of mildew.