Durability of proprietary cementitious materials for use in wastewater transport systems H. Saricimen * , M. Shameem, M.S. Barry, M. Ibrahim, T.A. Abbasi Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia Abstract Several methods and materials, such as high performance coatings, fiber glass reinforced linings, special mortars, brick or ceramic linings, etc., are used to protect concrete from sulfuric acid attack in a sewage environment. Two proprietary high alumina ce- mentitious lining materials, CC and SC, are recent additions to the list of protective materials used in the Arabian Gulf. This paper documents the findings of a laboratory study under accelerated conditions as well as a two-year field study of CC and SC in a wastewater lift station in Jubail, Saudi Arabia. In the laboratory investigations, 50 mm cube mortar specimens prepared using: (1) SC, (2) CC, (3) Type I þ 8% silica fume cement, (4) Type I þ 20% fly ash cement and (5) Type I cement were exposed to 2% sulfuric acid for 150 days. The laboratory specimens were tested for weight reduction, compressive strength, sulfate content, and alkalinity. In the field, the walls and ceiling of a wastewater manhole were coated using the proprietary lining materials, SC and CC, and were exposed to a normal sewage service environment. Performance of the liner materials was monitored for sulfate content and alka- linity after 6, 12 and 24 months of exposure. The analysis and evaluation test data generated from the accelerated laboratory study and the field study, which lasted for 24 months, showed that SC performed better than other materials tested in this investigation. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Concrete durability; Fly ash; Silica fume; Sulfate resistance; Wastewater transport systems 1. Introduction Sewer systems in the Arabian Gulf region undergo severe corrosion due mainly to sulfuric acid attack which causes a serious threat to the structural integrity of the system as well as a large amount of maintenance and repair cost. In the environmental conditions of the Arabian Gulf, concrete deterioration in sewer systems due to sulfuric acid formation is enhanced due to the elevated temperature conditions and scarcity of flush water [1]. Under anaerobic conditions in sewage environments, the sulfate-reducing bacteria reduce organic sulfur compounds to hydrogen sulfide (H 2 S). As H 2 S is a weak acid, it dissolves in the sewage under neutral or alkaline conditions. If the pH value decreases, e.g., due to aci- dification, it is emitted into the sewage atmosphere. Turbulence in the sewage flow is another cause for H 2 S emission. Once H 2 S reaches the atmosphere, it is ab- sorbed by the moisture on metallic and concrete surfaces of the structure. H 2 S then reacts with oxygen, in the presence of moisture and aerobic bacteria, thiobacilli, to form sulfuric acid, which leads to the corrosion of metallic and concrete surfaces. Several reports were published elucidating the mechanisms of concrete dete- rioration due to sulfuric acid formation in the sewerage environment [1–4]. Several methods and materials, such as high perfor- mance coatings, fiber glass reinforced linings, special mortars, brick or ceramic linings etc., are used to protect concrete from sulfuric acid attack in a sewage environ- ment. Two proprietary cementitious lining materials, ‘‘C’’ and ‘‘SC’’, are recent additions to the list of protective materials in this environment. This paper documents the findings of a laboratory study un- der accelerated conditions as well as the results of a two-year field study on the performance of ‘‘CC’’ and ‘‘SC’’ in a wastewater lift station in Jubail, Saudi Arabia. * Corresponding author. Tel./fax: +966-3-860-6658. E-mail address: sarici@kfupm.edu.sa (H. Saricimen). 0958-9465/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0958-9465(02)00082-3 Cement & Concrete Composites 25 (2003) 421–427 www.elsevier.com/locate/cemconcomp