14 June 2022
by Andrea Gaini

Bricks rise from wastewater

Bricks made with wastewater could help save clean water to attain circular economy goals.

pipe and water
© Kerem Karaarslan/Unsplash

The wastewater clay bricks show similar or better strength after testing compared with groundwater-fired clay bricks, claim researchers at the Pakistan Institute of Engineering and Technology, the American University of the Middle East, Kuwait, and the University of Stavanger, Norway.

The paper, Development of construction material using wastewater: an application of circular economy for mass production of bricks, outlines the process. It reads, ‘The mixed design criteria for brick preparation involve a combination of clay and water. Approximately 25% of water by total weight of clay is taken for the mixing of clay for brick preparation.

‘First, the lumps of clay are broken to ensure that no lumps are found in the clay. After this, the water is added into dry clay and left in the mixture for 2–3h to fill the voids for homogenous mixing. The brick mould size was 228mm×114mm×76mm in this study.

‘After homogenous mixing, the clay lump is put into the mould, and sand is used for lump coating to avoid sticking to the mould. For drying purposes, the bricks are dried for two to three days by the heat of the sun then put into a kiln for 10 days to burn at a temperature of more than 1,000oC.’

The study, published in Materials by MDPI, reports that both destructive and non-destructive tests have been conducted on all fired clay brick specimens as per the requirements of the American Society for Testing and Materials (ASTM).

‘In destructive testing, the compressive strength test was conducted on brick specimens...The load was applied in the direction of depth of burnt clay bricks, and the loading rate was 2.5kN/s.

‘In [non-destructive] testing, an ultrasonic sonic pulse velocity test was applied along the length of specimens. Essentially, with the help of this test, the flaws can easily be measured in the brick specimen.’

Physical (i.e. dimensions) and durability (water absorption, efflorescence, etc.) tests were also conducted. The paper reads, ‘The results obtained from wastewater bricks were approximately 19% better than ground surface water bricks.’


Andrea Gaini