Quantifying sorptivity using the contact sponge method: an improved calculation method validated by classical...

Area of Science:

• Building Materials Science
• Civil Engineering
• Material Characterization

Background:

• Non-destructive techniques like the contact sponge method (CSM) and Karsten tubes are used for field assessment of building material water absorption.
• Laboratory capillary rise tests (CR) typically use one-dimensional water flow on small specimens.
• Existing methods show qualitative agreement but lack robust quantitative correlation for sorptivity.

Purpose of the Study:

• To investigate water absorption processes using the contact sponge method (CSM) combined with neutron radiography.
• To address the lack of quantitative correlation between non-destructive field methods and laboratory tests.
• To develop an improved analytical model for sorptivity assessment.

Main Methods:

• Combined neutron radiography for direct water penetration visualization with conventional capillary rise tests (CR) using gravimetric measurements.
• Examined sandstones and limestones with porosities between 10% and 30%.
• Utilized neutron imaging to observe water flow dynamics during CSM.

Main Results:

• Neutron imaging revealed that the assumption of equal water penetration depth and lateral spreading in CSM is invalid.
• An improved analytical expression was developed, accounting for three-dimensional water flow in CSM.
• Significant improvement in quantitative agreement between sorptivity values from CSM and CR tests was achieved.

Conclusions:

• The standard assumption for CSM is not valid, necessitating a revised analytical framework.
• The proposed improved analytical expression enhances the reliability of sorptivity assessment using CSM.
• Adaptation of the CSM field-testing protocol ensures more accurate water absorption evaluations for building materials.