Water resistance - Absorption test


Main objective

Concrete structures are exposed to different weather conditions, soil, water and deicing agents. Crucial contribution to the deterioration processes in bridges or tunnels is assigned to water influence. Water works not only by reacting directly to reinforced concrete structure materials, but mainly by activating the chemicals present in the environment causing chemical reactions to progress. Water resistance measurement test is used as a characterization of durability of concrete elements and durability of the surface protections.

Measurement of water resistance allows to determine the space of pores and absorption rate in the concrete and should not be mistaken with a water penetration test since absorption and permeability values can be uncorrelated with each other.

Method of water absorption is widely used in determination of the effectiveness of hydrophobic surface agents used in securing building materials from the influence of water .


Functioning mode

In water absorption test, the cut out samples from the structure are dried in an oven for a specified time and temperature (usually 70±5)°C and then placed in a desiccator to cool. Immediately upon cooling the specimens are weighed. The material is then emerged in water at agreed upon conditions, often 23°C for 24 hours. After that time samples are removed, patted dry with a lint free cloth, and weighed. Sorption depends on both the capillary pressure and effective porosity. Capillary pressure is related to the pore size and effective porosity refers to the pore space in the capillary and gel pores. In addition, different pore size leads to different capillary pressure, and capillary pressure of concrete can be calculated by the average pore size .


Water absorption test can be divided in four types:

  • in laboratory:
internal water absorption observed – sample of concrete is fully submerged into water:
Fig. 1Internal water absorption test.
surface water absorption observed – sample of concrete is placed on the support creating a contact surface with water:
Fig. 2Surface water absorption test.
  • on-site:
measurement of the vertical transport of water and resistance to wind-driven rain penetration with an apparatus mounted on the surface under low pressure:
Fig 3. Vertical transport of water
measurement of the horizontal transport of water and resistance to wind-driven rain penetration with an apparatus mounted on the surface under low pressure:
Fig 4. Horizontal transport of water

Process/event to be detected or monitored

The test is used to detect increase in the mass of a specimen resulting from absorption of water as a function of time when only one surface of the specimen is exposed to water.

In case of on-site measurements the volume of water absorbed by a material within specified time period is detected.

Physical quantity to be measured (e.g. actions, displacements, deformations, dynamic structural properties, material properties including mechanical, electrical and chemical properties, relative displacements of the two sides of a crack, etc.).

Physical quantity measured is an increase of the mass of the sample or volume of water absorbed due to the capillary absorption of water on the surface or through the volume as a function of time.

Induced damage to the structure during the measurement

Damage is induced during initial stage when drilling in the structure to collect the samples.

In – case of on-site measurement no damage is induced or minor damage in process of mounting the measurement tubes.

General characteristics

Measurement type (static or dynamic, local or global, short-term or continuous, etc.)

Water absorption testing is a static and local measurement. Used in short-term investigation, which can be repeated in specified intervals of time.

Measurement range

Not applicable.

Measurement accuracy

Depends on the balance used for measuring the weight of the sample. Samples should be weighted with 0,01 mm accuracy and their dimensions defined with 1 mm accuracy.

Background (evolution through the years)

In general the water absorption test has been widely used in different industries and fields such as geology, material sciences, textiles etc. to test rate of absorption of water when the desired properties must be maintained due to different requirements .

In civil engineering most of the works concerning the water absorption test were focused on the effectiveness of the surface protection systems for concrete. In 2000 there was introduced polish norm concerning the products used for thermal insulation, defining the test procedure for determination of the water absorption during long-term immersion .

Current norm concerning the absorption test was introduced in 2019 - ISO 16535:2019-08, which includes two types of absorption test, equipment and procedures. It is used for thermal insulation products. Two methods are given in this document:

  • method 1: Partial immersion;
  • method 2: Complete immersion.

Water absorption with prolonged partial immersion is intended to simulate water absorption caused by prolonged exposure to water.


General points of attention and requirements

Design criteria and requirements for the design of the survey

Depending on the material the samples collected should have different dimensions:
  • concrete - cubic samples 100 mm x 100 mm,
  • stone – cubic samples 70 mm x 70 mm or 50 mm 50 mm,
  • cement-lime – bars 40 mm x 40 mm x 160 mm.

Procedures for defining layout of the survey

General survey layout for test performed in laboratory will consist of:
  • collection of the sample from the place of interest, depending on the material – choice of the dimensions of the samples,
  • drying of the samples and cooling to ambient temperature (20°C),
  • measurement of the dimensions of the samples,
  • placement of the samples in the cuvette with water an registering the hour,
  • covering the cuvette with foil to avoid evaporation from the samples,
  • after specified intervals – removing the samples, delicate drying and weighting directly after taking out,
  • inserting the sample again in the cuvette until next weighting period or removal of the sample,
  • determination of the mass change and water absorption rate from the formula,
  • conclusions.

Design constraints (e.g. related to the measurement principles of the monitoring technologies)

To receive reliable results the test should be performed under repeatable and controlled conditions.

Sensibility of measurements to environmental conditions

The measurement of water resistance of concrete is performed in a controlled environment, however the conditions to which the whole structure has been subjected during lifetime and therefore the sample drilled out will affect the results. From such factors one can mention: high humidity levels (which leads to pH level increase and temperature inside concrete), leaks, inadequate landscaping grade, poor drainage,


Procedures for calibration, initialisation, and post-installation verification

Water absorption test does not require any specific calibration process or post-installation verification since there are no electronic devices used, except the balance.

Procedures for estimating the component of measurement uncertainty resulting from calibration of the data acquisition system (calibration uncertainty)

No specific procedures. The weight should be calibrated as usual. Samples should be dried to constant weight, which means that the differences between two weighting between 24 h it’s not higher than 0,1% of the weight.

Requirements for data acquisition depending on measured physical quantity (e.g. based on the variation rate)

No specific requirements.


Requirements and recommendations for maintenance during operation (in case of continuous maintenance)

Not applicable. In this case no continuous maintenance is required.

Criteria for the successive surveying campaigns for updating the sensors. The campaigns include: (i) Georeferenced frame, i.e. the global location on the bridge; (ii) Alignment of sensor data, relative alignment of the data collected in a surveying; (iii) Multi-temporal registration to previous campaigns; and (iv) Diagnostics.

Not applicable.


Example of the report table after water resistance test is shown below:

Sample identification

Dimensions Concrete composition (if known) Temperature of drying Duration of drying Weight after drying Soaking time Weight after soaking Absorptivity


Table 1. Example of the water absorption test report

Lifespan of the technology (if applied for continuous monitoring)

Water resistance test is not used as for continuous monitoring.

Interpretation and validation of results

Expected output (Format, e.g. numbers in a .txt file)

Final output of the test is the calculated absorption coefficient as a number for an element on the basis of mass of the sample after soaking time.

Interpretation (e.g. each number of the file symbolizes the acceleration of a degree of freedom in the bridge)

Water absorption is expressed as increase in weight in percentage or a volume absorbed.
Percent Water Absorption = [(Wet weight - Dry weight)/ Dry weight] x 100
The lower the absorption, the better the result.


Specific methods used for validation of results depending on the technique

The water resistance test can be coupled with observation on Scanning Electron Microscope.

Quantification of the error

Standard deviation methodology can be applied.

Quantitative or qualitative evaluation

Both quantitative and qualitative analysis possible. Numerical methods are used for modelling ingress of moisture in concrete, which is essential for quantitative estimation of the service life of concrete structures .

Detection accuracy

Accuracy of the absorption level determination is affected by the preparation stage and the accuracy of balance used.


  • simple to perform
  • no specific qualifications needed for the operator.
  • can be performed on-site and in laboratory


  • does not account for any type of reactive process that ties up water
  • assumes that all the weight gain is due to water
  • short duration of submersion compared to what might happen in long term conditions.

Possibility of automatizing the measurements

Water resistance test may be partially automatized in such a manner that samples will be placed and taken out by a programmed equipment and the time of immersion will be designed in automatic software, however full procedure has to be supervised, taking into account the process of collecting the samples and decisions making.


The periods of time designed for the test depends on the porosity of the material under studies.

Existing standards

  • BS 1881: Part 122: 1983 - Method for Determination of Water Absorption.
  • ASTM C 642-90, Standard Test Method for Density, Absorption, and Voids in Hardened Concrete.
  • PN-EN 772-11:2011 Masonry test methods - Part 11: Determination of water absorption of aggregate concrete, artificial stone and natural stone masonry caused by capillary rise and initial water absorption of ceramic masonry elements.
  • PN-EN ISO 16535:2019-08 Thermal insulation products in construction - Determination of water absorption during long-term immersion.
  • RILEM Test Method – Test No. 11.4. Measurement of water absorption under low pressure.


Relevant knowledge fields


  • pulp and paper quality control,
  • powder testing,
  • thermal-insulating materials testing,


  • soil absorption testing.

Performance Indicators

  • spalling
  • cracks.

Type of structure

  • pavement slubs,
  • curbs
  • bricks

Spatial scales addressed (whole structure vs specific asset elements)

There are no specific asset elements for testing. However, method is useful in testing bricks, which absorbs water and release air.


  • concrete
  • polymer
  • aggregate
  • paper.

Available knowledge

Reference projects

Not reference projects.


BOSMAL – water resistance tests


[1] ASTM C 642-90, Standard Test Method for Density, Absorption, and Voids in Hardened Concrete. (n.d.)..
[2] BS 1881: Part 122: 1983 - Method for Determination of Water Absorption. (n.d.)..
[3] D. Smyl, F. G.-G. (2016). Modelling water absorption in concrete and mortar with distributed damage . Cnstruction and Building Materials vol. 125, pp. 438-449..
[4] Dias, W. (2000). Reduction of concrete sorptivity with age through carbonation. Cement and Concrete Research vol. 30, no. 8, pp. 1255-1261..
[5] Frances Gale, PROSOCO . (2020). RILEM Test Method No.11.4. Measurement of water absorption under low pressure . Lawrence : RILEM Technical Committee..
[6] G. D. Schutter, K. (2004). Evaluation of water absorption of concrete as a measure for resistance against carbonation and chloride migration. Materials and Structures vol. 37 no. 273, pp. 591-596..
[7] Hall, C. (1989). Water sorptivity of mortars and concretes: a review. Magazine of Concrete Research vol. 41, no. 147, pp. 51-61..
[8] International Society for Rock Mechanics. Commission on Standardization of Laboratory and Field Tests. Committee on Laboratory Tests. (1979). Suggested methods for determining water content, porosity, density, absorption and related properties and swelling and slake-durability index properties. Pergamon ..
[9] ISO 16535:2019-08. (n.d.)..
[10] Kelham, S. (1988). A water absorption test for concrete. Magazine of Concrete Research vol. 40, no. 143, 106-110..
[11] Krzywobłocka-Laurów, R. (2007). Water reppellent treatment of building products . Prace Instytutu Techniki Budowlanej vol. 36 no.1, pp. 17-46..
[13] Monteiro, P. K. (2006). Concrete: Microstructure, Properties and Materials. NewYork: McGraw-Hill..
[14] Monteiro, P. K. (2014). Concrete: Microsturcture, Properties and Materials, Chapter 11.5. McGraw-Hill Education..
[15] Neville, A. M. (2000). Właściwości betonu. Kraków: Polski Cement Sp. z o. o.,..
[16] Parrott, L. J. (1992). Water absorption in cover concrete. Materials and structures, 284-292..
[17] PN-EN 12087:2000. (2021, 12 13). Retrieved from https://sklep.pkn.pl/pn-en-12087-2000p.html.
[18] Reda Taha, M. M.-D. (2001). Sorptivity: a reliable measurement for surface absorption of masonry brick units. Materials and Structures, RILEM..
[19] S. Kartal, W. H. (2007, 10 1). Water absorption of boron-treated and heat-modified wood. . Journal of wood science vol. 53 no. 5, pp. 454-457..