The aim of this study was to investigate the deterioration of concrete sewers and identify responsible factors; this investigation was a part of an ongoing asset evaluation for Rennes (France). The sewer studied was a 300 mm spun concrete pipe laid in 1992. Core samples (D 28 mm, L 40 mm) were taken from different areas of a pipe (invert, crown and side wall) and analysed to quantify the condition of the concrete and the extent of damage to the internal and external surface of the pipe. Physical and mechanical properties of the material were characterised. The depassivation of the concrete was measured by testing with a phenolphthalein solution. The study showed that in this particular case the external corrosion was extensive with minimal internal corrosion.It is proposed that the corrosion was possibly linked to the use of a contaminated backfill or organic acids in the ground water. Recommendations are proposed concerning the direction of future research.

Abstract

Lignin is the second most abundant natural polymer. Due to the high content of carbon and hydrogen (C-H, C-C, C=O), it can be used as a potential dispersant for cement matrix. The objective of this study is to extract lignin from date palm and study its effect in the form of black liquor (BL) on the rheological and physic-mechanical properties of the cements and concrete. The lignin in black liquor form represents approximately 30 wt% dry weight of date palm. It is a heteropolymer composed primarily of methoxylated phenylpropylene alcohol monomeric units interconnected by a variety of stable carbon-carbon and carbon-oxygen-carbon (ether and esters) linkages. The results found show the positive effect on the workability of cement and concrete and confirms its dispersion effect by improving compressive strength of concrete during the early and the later ages of hydration.

No abstract

The deterioration and cost-effective maintenance of infrastructure has for many years been an area of social and financial importance. The deterioration of the wastewater infrastructure is particularly important because of its key role in the maintenance of public health for urban conglomerations. This paper describes two case studies that are taken from an ongoing study of the sewerage network in the Municipality of Rennes, France. Both studies concern spun concrete pipes laid approximately 55 years ago. The first case is that of a sewer in good order because of its location within the network and its design. The second case describes a sewer that has been oversized and the conditions within the reach of the sewer have led to sulphide attack. It is concluded that two important considerations that must be taken into account is the design detailing and appropriate selection of materials.