Question Your World: Can Coffee Make Concrete Stronger?

Posted: September 8, 2023

You know what makes the morning better? Coffee.

You know what makes late night productivity possible? Coffee.

You know what makes concrete stronger? Yep, you guessed it ... coffee!

A recent article published by a team of researchers is showing off the ever-growing superpowers of coffee! This research was done in Australia, where nearly 75,000 metric tons of spent coffee grounds end up in landfills annually. Decaying organic material, like coffee grounds, produces methane, which is a super powerful greenhouse gas.

Meanwhile the concrete needs of the region continue to grow. Traditionally, one of the ingredients needed to make concrete is sand. Sand has to be excavated from natural environments like dunes, beaches, riversides and so on. 

The goal here was to see if there was a way to reduce the amount of organic products entering landfills and find an alternative to sand that could be used for concrete production. No, they don’t just splash some coffee on the sidewalk, there’s way more to it. This process involves trying different temperatures and amounts!

One thing the researchers learned is you can’t just dump a bunch of spent coffee grounds into the mixture ... it has to be the right ratio! The researchers tried 0%, 5%, 10%, 15% and 20% spent coffee grounds to replace the sand conventionally used for concrete. The spent coffee grounds also needed to be prepared by heating them without oxygen at super-high temperatures.  

So, what were the results? 

Concrete samples that had replaced sand with 15% coffee grounds prepared at 662 degrees Fahrenheit had a nearly 30% uptick in compressive strength

Using spent coffee grounds will not only reduce the excavation of sand from natural environments, but this process will also prevent some spent coffee grounds from ending up in landfills. This could make a noticeable impact as humanity produces billions of pounds of spent coffee grounds every year! Now these researchers are ready to conduct long-term tests on the durability of this new coffee-concrete. 

The idea of coffee grounds for alternative uses is not brand new to science. Similar tests have been conducted in the past to see if coffee grounds can help make durable patches of roads as well. 

Coffee ... it's a pretty amazing product really. The java juice lowers the risk of diabetes, provides antioxidants, enhances physical activity, sharpens memory, reduces the risk of some diseases AND can concrete stronger. If this technology becomes commonplace one day, then your morning coffee could literally be one for the road!