Compressed and stabilized soil blocks with fly ash-based alkali-activated cements

摘要

In this study, blocks were manufactured from clay soil and alkali-activated binders. The soils used were classified as A-4 and A7-5 according to ASTM D3282. The binder was produced from fly ash with a high content of unburned material (carbon). Blast furnace slag and lime were used as calcium sources. The physical-mechanical results of the blocks showed that the texture of the soil is a very important parameter for manufacturing this type of compacted soil masonry element, because the soil with the highest sand content (soil A-4) showed a higher dry density, indicating that this property corresponded to a lower percentage of permeable pores, a lower water absorption and an average compressive strength of 17 MPa at an age of 28 days. A life cycle analysis of the blocks was carried out and the results compared to that of the concrete paving blocks and fired clay blocks, which showed that the Global Warming Potential (GWP) can be reduced from 38 to 75%. Of the materials used to prepare the activated blocks, lime and silicate generate the greatest impact. In general, the results show the technical feasibility of manufacturing alternative blocks to traditional pavers with alkaline activation processes by using natural soils as the basic raw material and a low-quality fly ash as precursor. (C) 2020 Elsevier Ltd. All rights reserved.