The water absorption test is used to measure the amount of moisture that a roofing tile can absorb. If the water absorption rate is too high, the tile may crack, which is not desirable. This test reflects the tile’s suitability for roofing applications, as roofing tiles should have a low absorption capacity, especially in areas that experience rainfall, freezing, and thawing cycles. Water absorption is expressed as a percentage of the weight of water against the dry weight of the individual tiles.
Different codes around the world have established methods for conducting the water absorption test, such as the American Standard for Testing Materials and Indian Standard. According to ASTM C373, non-porous tiles typically exhibit a water absorption rate of 0.1-0.5%, while porous tiles can have a water absorption rate in the range of 9-15%.
Aim of the Test
The percentage of water absorption of roofing tiles is a crucial factor that determines their durability and performance over time. This value is typically expressed as a percentage of the weight of the tile after it has been exposed to water for a certain amount of time.
To determine the percentage of water absorption, the roofing tiles are first weighed, and then immersed in water for a specified period. After the immersion period is complete, the tiles are removed from the water, and their weight is measured again.
The percentage of water absorption can then be calculated by taking the difference between the weight of the wet tile and the weight of the dry tile, and dividing that number by the weight of the dry tile. This value is then multiplied by 100 to obtain the percentage of water absorption.
Roofing manufacturers and contractors use this information to determine the suitability of different types of tiles for specific roofing applications, and to ensure that their products meet industry standards for durability and performance.
Apparatus
In order to accurately measure weights with a precision of 0.01 g, it is necessary to have a balance or scale that has a sufficient capacity and accuracy. Additionally, it is important that the balance or scale is appropriate for the specific weighing requirements.
For processes that require heating, an oven that is capable of maintaining a temperature of at least 150 C is necessary. This will ensure that the required temperature is maintained consistently throughout the heating process. It is important to choose an oven that is suitable for the intended use and is capable of achieving the required temperature range.
Specimen
Two tiles shall be used for this test from the sample selected.
Procedure
To dry the selected tiles, an oven should be used at a temperature ranging from 105°C to 110°C. The tiles must be kept in the oven until they attain a constant weight, following which they should be cooled and weighed (M1). Once cooled, the dry specimens should be immersed entirely in clean water at a temperature of 27±2°C for a duration of 24 hours. After the 24-hour immersion period, the specimens should be carefully removed from the water, and any surface water should be wiped off using a damp cloth. The specimen’s weight closest to one gram should then be taken (M2) within three minutes of removing it from the water tank.
Calculation
The equation provided, Equation 1, can be used to calculate the percentage of water absorption in a specimen. This percentage value represents the amount of water that the specimen has absorbed and is expressed in terms of the weight of the specimen. The equation takes into account two weights: the weight of the dry specimen (M1) and the weight of the specimen after it has been immersed in clean water for 24 hours (M2). The formula calculates the difference in weight between M2 and M1, then divides it by M1, and finally multiplies the result by 100 to express the value as a percentage.
Results
Water absorption of the given roofing tiles= ………………..%