American Society of Civil Engineers


A New Generation of Cementitious Materials for Mortar Lining of Buried Pipes


by E. N. Allouche, (Associate Director, Trenchless Technology Center, 600 W. Arizona, Engr. Annex, P.O. Box 10348, Ruston, LA 71272 E-mail: allouche@LaTech.edu), C. Montes, (Ph.D. Candidate, Trenchless Technology Center, 600 W. Arizona, Engineer Annex, P.O. Box 10348, Ruston, LA 71272 E-mail: cmo021@LaTech.edu), and E. I. Diaz, (Ph.D. Candidate, Trenchless Technology Center, 600 W. Arizona, Engineer Annex, P.O. Box 10348, Ruston, LA 71272 E-mail: ivandilox@hotmail.com)
Section: New Technologies I, pp. 1-9, (doi:  http://dx.doi.org/10.1061/40934(252)99)

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Document type: Conference Proceeding Paper
Part of: Pipelines 2007: Advances and Experiences with Trenchless Pipeline Projects
Abstract: Concrete (reinforced and non-reinforced) and asbestos cements pipes represent a significant percentage of the storm and wastewater collection systems in many cities across North America. A significant percentage of these pipeline networks are approaching or have already exceeded their 50-year design life. These pipes are in various stages of deterioration, generally due to microbiological induced corrosion or mechanical loading (either external or internal). Open-cut replacement of these pipes, many placed beneath busy streets, is costly and involves a lengthy disruption to normal traffic and business activates. Common rehabilitation techniques for such structures include lining using a thermoplastic or thermosetting liner product or coating using epoxy-based or cementitious-based materials. The latter is in many cases the most economical approach, but the durability of most cementitious lining products in harsh environments limits their useful design life. Hybrid materials, such as polymer concrete, provide superior performance but at higher costs. Geopolymers are inorganic alumino-silicate polymers that come from chemical reactions under highly alkaline conditions between an active puzzolanic material (such as fly ash or metakaolin) and an activator solution (based on a molar mixture of sodium hydroxide and an alkaline silicate, e.g., sodium or potassium silicate). Geopolymers are usually referred to as inorganic alumino-silicates, and are known for their excellent mechanical properties, high corrosion resistance and chemical stability. Another promising cementitious material is Zeolite, a crystalline puzzolanic aluminosilicate material with uniform molecular sized pores. At present Zeolites are used as catalysts, separation media, ion exchangers and antimicrobial agents. Zeolites can be mixed with sand to form mortar blends that are highly stable in acidic environments. The paper provides a state-of-the-art review of these two cementitious materials and their chemical and mechanical properties. Thereafter, an experimental testing program undertaken at the Trenchless Technology Center to explore the suitability of these two novel materials for use as coatings for wastewater conveyance, storage and treatment structures is described and its preliminary results reported. Specifically, the effect of various mix design parameters (AS/FA ratio, curing temperature, type of silicate used and NaSiO2 to NaOH ratio) on the compressive strength of geopolymer mortar cubes are reported and discussed.


ASCE Subject Headings:
Buried pipes
Cement
Material properties
Mortars