Used coffee grounds can make concrete stronger

 

The RMIT University engineers were in the school’s kitchen when they saw a trashcan filled with used coffee grounds. Dr. Rajeev Roychand, the lead author of the study, pondered how the research team could find a way to recycle these used coffee grounds instead of letting them end up in landfills. They gathered the waste, roasted them at 350 degrees Celsius using a low-energy process without oxygen, and came up with a result and technique that can make concrete 30% stronger by turning waste coffee grounds into biochar.

 

The research team – composed of Dr. Rajeev Roychand, Dr. Shannon Kilmartin-Lynch, Dr. Mohammad Saberian, Professor Jie Li, Professor Guomin (Kevin) Zhang, and Professor Chun-Qing Li – employs the process called Pyrolysis which involves heating organic waste in the absence of oxygen.

 

Their experimental project looks at pyrolyzing used coffee grounds at different temperatures – mainly 350 and 500 degrees Celsius – to know how it can improve the physicochemical and mechanical properties of concrete. In this way, the engineers are giving the used coffee grounds a ‘double shot’ in life by turning them into an ingredient that can strengthen concrete rather than pouring them all into landfills.

used coffee grounds concrete stronger
header: person holding coffee beans, photo by Nathan Dumlao | images and video still by researchers at RMIT University

 

 

Pyrolyzed used coffee grounds can replace sand in concrete

 

The pyrolyzed used coffee grounds at 350 degrees Celsius then are combined with concrete as the replacement for fine sand. After a series of examinations and scans, the engineers at RMIT University found that the substance improved the material properties of concrete, which resulted in a 29.3% enhancement in the compressive strength of the concrete blended with coffee biochar.

 

Dr. Rajeev Roychand says that several councils have shown interest in their work and have engaged the research team for their upcoming infrastructure projects. They aim to test their technique and try using used coffee grounds in hopes of making concrete infrastructure up to 30% stronger. The study and technique can help reduce the use of sand to make concrete and replace it with coffee biochar.

 

Corresponding author and research team leader Professor Jie Li says that the ongoing extraction of natural sand around the world, which is typically taken from river beds and banks, has a big impact on the environment. By roasting the used coffee grounds without oxygen and mixing the substance into the concrete-making process, ‘it could keep organic waste out of landfill and also better preserve our natural resources like sand,’ adds Professor Li.

used coffee grounds concrete stronger
the research team employs Pyrolysis which involves heating organic waste in the absence of oxygen

used coffee grounds concrete stronger
the study documents a 29.3% enhancement in the compressive strength of the concrete blended with coffee biochar

 

 

project info:

 

name: used coffee grounds for concrete

institution: RMIT University
team: Dr. Rajeev Roychand, Dr. Shannon Kilmartin-Lynch, Dr. Mohammad Saberian, Professor Jie Li, Professor Guomin (Kevin) Zhang, and Professor Chun-Qing Li