Novel technology for low-CO2 concrete using ash recycled from the hemp industry**

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Portland cement is one of the most used construction materials in the world. It is the essential component in the production of concrete. Approximately 13 million tonnes of cement were produced in Canada in 2014. It is estimated that cement production is responsible for 5%-7% of global CO2 emissions. CO2 is considered to be the primary greenhouse gas driving global climate change. National cement and concrete producers are actively looking for ways to lower their CO2 output. One of the ways to do so is to reduce the amount of cement in a concrete mix, by replacing it with supplementary cementitious materials (SCMs). SCMs are either naturally occurring products/by-products, or may be manufactured by-products from other industries. Some common examples of SCMs which occur as industrial by-products include fly ash, ground granulated blast furnace slag, and silica fume. In fact, production of fly ash is decreasing with time as coal fired electricity generating plants are being phased out. In October 2018, the Canadian Cannabis Act came into force, which legalized the use of recreational marijuana. A survey of major Canadian Cannabis producers indicates that by the end of 2020, 2.3-2.4 million kilograms of Cannabis could be produced on an annual basis. While the cannabis leaf will be of primary use, in the process, hundreds of thousands of kilograms of waste in the form of Cannabis stems will have to be disposed of. If this waste material is sent to a landfill, it will decompose, and with time, release CO2 into the atmosphere. Under similar circumstances, global producers of other major organic crops have been able to use their waste material as SCMs in concrete mix designs. It is possible that waste Cannabis stems could be used as an SCM in concrete production. Similarly, the purpose of this study is to examine the possibilities of using incinerated waste Cannabis stalk in cement production. The research outcomes of national benefit are the possible identification of a new SCM for cement producers, a potential solution for Cannabis producers to deal with their waste stems, and overall contribution to the goal of reducing CO2 emissions to meet national targets.