Cof­fee more than just a drink for Swin­burne engineers

Swin­burne Uni­ver­sity of Tech­no­logy engin­eers have turned used cof­fee grounds into build­ing mater­i­als for roads. Pro­fess­or Arul Arulra­jah, who leads the geo­tech­nic­al group in the Centre for Sus­tain­able Infra­struc­ture, has been invest­ig­at­ing the use of recycled mater­i­als, such as crushed brick or glass and con­crete, for use in road con­struc­tion. He is also an avid cof­fee drink­er. ​“I see the baris­tas throw­ing away the used cof­fee grounds and I think, ​‘why not look at this as an engin­eer­ing mater­i­al?’” he says. Pro­fess­or Arulra­jah and PhD can­did­ate Teck-Ang Kua col­lec­ted used cof­fee grounds from cafés sur­round­ing Swinburne’s Hawthorn cam­pus. They dried them in a 50°C oven for five days, then sieved the grounds to fil­ter out lumps. They then mixed sev­en parts cof­fee grounds with three parts of slag – a waste product from steel man­u­fac­tur­ing. A liquid alkaline solu­tion was added to bind everything togeth­er. The mix­ture was com­pressed into cyl­indric­al blocks that proved strong enough to use as the sub­grade mater­i­al that sits under a road sur­face. ​“On aver­age the cafés we col­lect from dis­pose of about 150 kg of cof­fee grounds per week,” says Pro­fess­or Arulra­jah. ​“We estim­ate that the cof­fee grounds from Melbourne’s cafés could be used to build five kilo­metres of road per year. This would reduce land­fill and the demand for vir­gin quarry mater­i­als.” This research is a col­lab­or­a­tion with Sur­anaree Uni­ver­sity of Tech­no­logy, Thai­l­and; South­east Uni­ver­sity, Nanjing, China; and Shang­hai Jiao Tong Uni­ver­sity, China. It has been pub­lished in Con­struc­tion and Build­ing Mater­i­als. Quelle: Swin­burne University