Exactly what does the Uniform Building Code require if sulfates are found in the soil?
Since 1979, the Uniform Building Code has required that a special Type V cement be used in high-sulfate soils, and that a lower water-to-cement ratio be used to maintain a proper level of density in the concrete after curing. Dense concrete stops groundwater from seeping in; it’s the water that carries the sulfates. According to the UBC, the ratio of water-to-cement in high-sulfate soil conditions should be no more than 0.45. However, in many cases that have been investigated, the ratio is more like 0.65 to 0.70, or 50% in excess of maximum. The result is concrete with an interconnected pore structure, and therefore not dense. The denser the concrete, the less likely the water will seep in.
