There is little technical data on methods to estimate service life for reinforced concrete. In department experience when cast-in-place and precast reinforced conduit is used in appropriate environments, service life exceeds the original design life of the project (typically in excess of 50 years).

Durability of reinforced concrete can be affected by acids, chlorides, and sulfate concentrations in the soil and water. If the pH value is 6.5 or less, the use of porous concrete pipe with shell thickness of 1 in. (25 mm) or less is not advisable. If the pH value is 5.5 or less, use of reinforced concrete without a protective coating of epoxy or other acceptable coating is not advisable.

Salt content of the soil and water can have a detrimental effect on reinforced concrete because the salt (with its chloride constituent) can permeate the concrete in time, threatening the embedded reinforcing steel. Sulfate content in the soil or water can have a detrimental effect on reinforced concrete facilities. The following table presents a guide for adjusting cement type and factor for sulfate content in soils and runoff.

Guide for Sulfate Resisting Concrete

Water-soluble sulfate in soil sample (%)	Sulfate in water sample (ppm)	Type of cement	Cement factor
0 - 0.20	0 - 2,000	II	Minimum required by specifications
0.20 - 0.50	2,000 - 5,000	V II	Minimum required by specifications 7 sacks
0.50 - 1.50	5,000 - 15,000	V II	Minimum required by specifications 7 sacks
over 1.50	over 15,000	V	7 sacks