Application of biochar for the development of carbon sink building materials

During recent decades, a lot of research has been carried out on the use of biochar as soil amendment or, more generally, in the agriculture-related sector. On the contrary, its application in the building field is quite unexamined and the enormous potential of biochar within this context still needs to be explored. Cement-based materials could represent a very attractive research topic, since concrete is the construction material most widely used in the world and its industry has a high impact on environment. The aim is to obtain green cementitious materials able to address the ecological issues by adding biochar in their admixture, so as to capture and store - in a stable form - carbon in buildings for decades. Actually, little research exists on the addition of biochar in cement mortar and none, to the knowledge of the Authors, focusing on biochar produced from gasification process. Therefore, this work is focused on the feasibility of using biochar derived from gasification of wood waste of local forests as carbon sequestrating additive in cement mortars, with the aim of not diminishing their structural performance or even obtaining enhanced mechanical properties. Two mortar mixes are investigated: a conventional plastic mortar M0, composed of cement and sand, and an innovative one M1, which is obtained by employing the same mix proportion but with the addition of biochar, at 1% by weight of cement, as reported in Table 1. The results obtained after 28 days of water curing highlight that the addition of biochar does not significantly influence compressive strength fc and flexural strength fc,fl, while fracture energy Gf is increased (see Figure 1); hence, the production of biochar-added mortars seems promising.