An accelerated test to assess the quality of recycled concrete sands based on their absorption capacity

• The standard test to determine the absorption of sands is long and laborious.
• A fast method to test the water absorption of recycled sands has been developed.
• The new test uses an electronic moisture analyzer based on thermogravimetry.
• The new test is fast and simple, being an automatic process with no operator need.
• The absorption results have been satisfactory compared to the standard method ones.

The standard test to determine the absorption of sands according to UNE-EN 1097-6 is long and laborious to carry out, even more when it is applied to recycled sands due to its typical high absorption.The aim of this study has been to develop a fast and reliable method to test the absorption of recycled sands. For that purpose, the absorption of fourteen recycled concrete sands has been determined using an electronic moisture analyzer based on thermogravimetry. This analyzer provides thermogravimetric curves (weight–time curves) from which drying rate–humidity and drying acceleration–humidity curves can be plotted. The results have been satisfactory compared to those by the standard method for all the recycled sands. The new test is fast (around half an hour) and simple, being an automatic process with no operator need and providing a numerical result.This method can also be used for accelerated tests of recycled sands after an immersion period of 10 min. In the experimental programme, it has been established a correlation between absorption after 10 min and 24 h immersion in water for the recycled sands.