Wood shavings and alkali-activated slag bio-composite

Abstract

Manufacture of green building materials has been increasing recently. There are many scientific publications related to lignocellulosic waste incorporation in Portland cement systems, but only few research works on the waste recovery in alkali-activated binders can be found. Alkali-activated materials could be a choice of ecological and renewable materials due to good durability, as well as mechanical and thermal properties. The paper analyses the performance of bio-composite material made of alkali-activated slag with the addition of phosphogypsum at 5 wt% by weight of slag or at 3.6 wt% by weight of other bio-composite components including softwood shavings (WS). Relationships between density, compressive and flexural strength, thermal conductivity and WS content were observed. The microstructure of bio-composite specimens was also examined. Usually, alkali-activated binders have relatively low flexural strength, which limits their application possibilities. In this work, it was succeeded to increase the flexural strength by incorporating wood shavings (WS) in this binder. According to the results, the appropriate addition of WS can improve the flexural properties of alkali-activated slag bio-composites, especially at later ages of 28 days. It is concluded that bio-composite from alkali-activated slag blended with WS has a great potential in construction materials industry. Depending on the composition, this bio-composite had flexural strength of 10.7 MPa, compressive strength of 11.5 MPa, and thermal conductivity of 0.30 W (mK)−1. The main practical advantages of this bio-composite are based on practical demand: the mechanical, thermal properties and waste utilization aspects are balanced.