Assessment of the effect of natural hydraulic lime on the stabilisation of compressed earth blocks

Earthen construction is an alternative construction method that allows for the reduction of the embodied energy of building materials and the promotion of sustainability in the construction sector. Among the different earthen building techniques available, compressed earth blocks offer a remarkable potential for industrialisation. Due to the drawbacks associated with the use of non-stabilised blocks, such as the impact of weathering, previous researches had addressed the development of compatible stabilisers for performance improvement. Lime is a traditional binder whose properties are compatible with earth, especially when fine particles are present. Yet, there is limited research on the use of natural hydraulic lime, as most previous studies have focused on the use of hydrated lime, which requires an extended curing time. In the present study, two types of natural hydraulic limes (NHL2 and NHL3.5), in ratios ranging from 3% to 12%, were investigated for the stabilisation of compressed earth blocks. The results revealed that the replacement of soil with lime led to a reduction of the bulk density of the samples of up to 12.8% while increasing their mechanical strength by 48-56% and 12-35% in NHL2 and NHL3.5 respectively. Furthermore, the type of lime has a clear influence on the pore size and volume, and consequently, on both the capillary absorption and the absorption under atmospheric pressure. The results suggested that the addition of NHL2 induced an increase in pore size and volume, in line with the behaviour exhibited by hydrated lime, while the opposite took place when NHL3.5 was used. (C) 2020 Elsevier Ltd. All rights reserved.