Concrete sewer pipe corrosion induced by sulphuric acid environment

Corrosion of concrete sewer pipes induced by sulphuric acid attack is a recognised problem worldwide, which is not only an attribute of countries with hot climate conditions as thought before. The significance of this problem is by far only realised when the pipe collapses causing surface flooding and other severe consequences. To change the existing post-reactive attitude of managing companies, easy to use and robust models are required to be developed which currently lack reliable data to be correctly calibrated. This paper focuses on laboratory experiments of establishing concrete pipe corrosion rate by submerging samples in to 0.5 pH sulphuric acid solution for 56 days under 10ºC, 20ºC and 30ºC temperature regimes. The result showed that at very early stage of the corrosion process the samples gained overall mass, at 30ºC the corrosion progressed quicker than for other temperature regimes, however with time the corrosion level for 10ºC and 20ºC regimes tended towards those at 30ºC. Overall, at these conditions the corrosion rates of 10 mm/year, 13,5 mm/year and 17 mm/year were observed

Predisposing Factors.

<p>Predisposing Factors.</p

Significant Factors Associated with Four Levels of ED Utilization.

<p>Significant Factors Associated with Four Levels of ED Utilization.</p

Need Factors.

<p>Need Factors.</p

Mean (sd) daily nutrient intake estimated by the average of 24DRs and two SFFQs in urban (n = 89) and rural (n = 67) areas.

<p>Mean (sd) daily nutrient intake estimated by the average of 24DRs and two SFFQs in urban (n = 89) and rural (n = 67) areas.</p

Bland and Altman plots for macronutrients with the mean difference and limits of agreements.

<p>Bland and Altman plots for a. energy, b. protein, c. fat, and d. carbohydrate with the pone.0037958.g003.tifmean difference (solid line) and 95% limits of agreements (Dashed lines) in urban areas.</p

The design of SFFQ validation in urban setting.

<p>The design of SFFQ validation in urban setting.</p

Validity Pearson correlation coefficient between daily consumption of nutrients estimated by SFFQ2 vs. 24DRs in urban (n = 89) and rural (n = 67) area.

<p>Validity Pearson correlation coefficient between daily consumption of nutrients estimated by SFFQ2 vs. 24DRs in urban (n = 89) and rural (n = 67) area.</p

Demographic characteristics of individuals who participated in validation study, urban (n = 89) and rural (n = 67) areas.

<p>Demographic characteristics of individuals who participated in validation study, urban (n = 89) and rural (n = 67) areas.</p

Repeatability, Pearson correlation coefficient between two SFFQs in urban (n = 89) and rural (n = 67) areas.

<p>Repeatability, Pearson correlation coefficient between two SFFQs in urban (n = 89) and rural (n = 67) areas.</p