A Framework for Structural Design of Geopolymer Spray Applied Pipe Lining

Spray applied pipe lining (SAPL) is a trenchless technology renewal technique for gravity flow conduits such as culverts, storm drain, storm sewer, etc. SAPL can enhance structural and hydraulic capacity of deteriorated conduits. SAPL is widely used by departments of transportation (DOTs) and municipalities. However, there is no known standard design methodology available for SAPLs. This paper proposes a design methodology framework for flexible culverts renewed with geopolymer SAPL through an analytical approach. The outcomes are compared and verified with a set of large-scale soil box testing. The soil box testing includes CMPs with 6 ft in length and 60 in. diameter. The invert of these CMPs were cut to simulate fully invert-deteriorated culverts in field conditions to eliminate ring stiffness of the host pipe and to maximize the applied load on the geopolymer SAPL. The CMP samples were buried under 2 ft of soil cover. Once the pipes were backfilled, they were renewed with geopolymer SAPL. The results showed that the proposed analytical approach which is derived from Marston's Iowa equation is in an acceptable conformity with the test results.