Corrosion of Metallic Pipe in Controlled Low-Strength Materials—Parts 1 and 2

Abstract

Controlled low-strength material (CLSM) is a cementitious material that is commonly used as a backfill for trenches, often when these trenches are located in roadways and undergo repeated loadings from vehicular traffic. However, when CLSM are proposed for use, engineers are often forced to use predictive corrosion performance tools applicable for pipes embedded in soils. These tools may not accurately represent the corrosion performance of pipe embedded in CLSM. This article reports on a two part study that investigated the corrosion performance of ductile iron pipe in sand (Part 1), in 30 different CLSM mixtures (Part 1), and in a combination of sand and CLSM (Part 2). Results show that for nearly all cases, the corrosion (measured by mass loss) of ductile iron coupons completely embedded in CLSM was less than the corrosion of pipe coupons embedded in sand backfill material. The results from Part 2 of the study indicate that embedding ductile iron pipe in different environments (in this case CLSM and sand) results in an increase in the corrosion activity. The authors conclude that because CLSM exhibits the potential to minimize corrosion of metallic pipes embedded in this material, proper precautions in preventing galvanic corrosion (corrosion caused as a result of being placed in different environments) may be worthwhile.