Document Type : Original Article

Authors

• Ali Saberi Varzaneh ¹
• Mahmood Naderi ²

¹ Postdoc researcher, Civil Engineering Faculty, Imam Khomeini International University, Qazvin, Iran.

² Professor, Civil Engineering Faculty, Imam Khomeini International University, Qazvin, Iran.

Abstract

Extended Abstract
Introduction
This study aimed to evaluate the permeability of a water supply canal and to quantify water losses arising from the inefficiency of the concrete lining. The “cylindrical chamber” test was proposed and implemented as an in-situ, non-destructive method. A total of 54 concrete specimens—27 water-cured and 27 cured under ambient conditions—were tested using the cylindrical chamber method under a constant pressure of 5 bar for 5 hours. To validate the results, the BS EN 12390 8 standard test was also performed on the same specimens, and regression analysis was conducted between the two methods. The results showed a correlation coefficient of 0.98, indicating high accuracy of the in-situ test. For field applications, direct measurement of penetration depth is impractical, as it is inherently destructive and requires core extraction from the structural element. To overcome this limitation, one of the key advantages of the cylindrical chamber method was employed—its ability to measure the total volume of water infiltrating the concrete surface over a fixed time under a constant hydraulic head. Statistical analysis of the differences between this study and reference data, using mean absolute percentage error (MAPE) and linear correlation coefficient (R²), showed that the mean infiltration volume differed by less than 10%, with R² = 0.97. These results confirm the low deviation and strong correlation, indicating the accuracy and reliability of the cylindrical chamber test for classifying concrete permeability. In-situ measurements at 11 selected points along the Varzaneh city water supply canal revealed infiltration volumes exceeding 25 mL at all locations, falling within the high-permeability range and signifying substantial water losses. Mercury intrusion porosimetry and SEM imaging further showed that the absence of curing increased porosity and total pore volume by 7% and 69.4%, respectively.
Methodology
The cylindrical chamber method is a precise and versatile technique for quantifying the permeability of concrete and similar construction materials under laboratory or field conditions. The testing procedure comprised the following steps:
1. Surface preparation: The concrete surface was dried to a constant mass, and all surface contaminants were removed to ensure proper adhesion.
2. Fixture installation: A steel annular ring was bonded to the prepared concrete surface using epoxy adhesive. After full curing of the adhesive, the cylindrical chamber was mounted securely on the metal fixture.
3. Water pressurization: The chamber was filled with de-aired water, and the internal pressure was applied using a calibrated hand-operated lever. The imposed water pressure—5 bar (0.5 MPa)—was continuously maintained and monitored via the gauge installed on the apparatus.
4. Testing duration: Pressure was sustained for 5 hours on the exposed concrete surface.
This method allows quantification of water infiltration without sample extraction, thereby preserving the structural integrity of the tested element.
Results and Discussion
Selected outcomes of the in-situ cylindrical chamber tests on the Varzaneh canal are summarized in Table 6. While numerous measurements were performed along the entire length of the canal, representative results are reported here to illustrate key trends. The findings confirm that the concrete lining of the Varzaneh water supply canal exhibits very high hydraulic permeability, significantly exceeding recommended thresholds. In the evaluated sections, the infiltration volumes surpassed 25 mL, classifying them in the high-permeability range per the adopted criteria. Such elevated permeability is directly associated with excessive seepage losses, contributing to increased water demand and reduced delivery efficiency. These observations strongly suggest that the measured reduction in outflow is not the result of unauthorized water extraction along the canal’s route. Rather, the dominant factor is the inadequate impermeability of the concrete lining, which permits substantial leakage through the canal body.
Conclusions
- Regression analysis revealed a strong linear correlation (R² = 0.98) between the cylindrical chamber method and the BS EN 12390 8 (British Standard) test, confirming the reliability of the field measurements. This enabled accurate in-situ assessment of the Varzaneh canal’s permeability without inducing structural damage.
- Concrete with an infiltration volume < 12 mL is classified as low permeability; 12–25 mL denotes medium permeability, and > 25 mL corresponds to high permeability. The majority of tested points on the Varzaneh canal exceed 25 mL, indicating widespread high-permeability zones.
- The substantial difference between inflow and outflow in the canal is primarily attributable to leakage through the concrete lining, rather than unauthorized withdrawals. Consequently, a large proportion of the supplied water fails to reach its intended destination in the city of Varzaneh.

Keywords

• Permeability
• flow reduction
• concrete
• in-situ test

Main Subjects

• Irrigation network management