# Performance of Ore Sand as Aggregate for Interlocking Blocks
## 3 Results
### Production Impacts  
As part of the scope and goal of this work, the environmental impacts of the aggregates used to manufacture conventional paving blocks and paving blocks with the addition of ore sand were evaluated. With the data obtained from the life cycle inventory analysis of aggregate production (Table 2), it was possible to quantify the environmental impacts of block production in eleven impact categories using the CML 2001 method. Figure 6 shows the comparative results (highest result divided by the lowest) in each of the impact categories for aggregates used to manufacture 60,000 blocks (excluding impacts associated with transportation). As noted in Section 2.3, only the impacts of producing the aggregates (not of manufacturing the blocks) are considered because the latter process is the same regardless of the aggregates used. Table 3 shows the results obtained for the categories evaluated with the percentage reduction in impacts with the replacement of natural resources by ore sand. A reduction in impact was observed for all categories, with abiotic depletion having one of the highest reductions. This category accounts for minerals and resources used and is influenced mainly by the rate of resource extraction [38; 40]. To minimize abiotic depletion, sustainable practices in the extraction and use of non-living resources need to be promoted. Such practices include reducing consumption via recycling and circular-economy practices, developing more efficient extraction and processing techniques, and promoting the use of alternative and renewable resources. The replacement of 100% of the limestone sand and 13.3% (98.2 t to 85.1 t) of the natural sand with iron ore tailings resulted in an average overall reduction of 30% in all environmental impacts compared to using conventional aggregates in the manufacture of interlocked blocks.  
The graphical representation in Figure 6 illustrates the relative contributions of limestone sand, gravel, and natural sand to the impact categories assessed during the production of conventional and ore-sand blocks. These assessments follow the predefined limits established for life cycle assessment (goal and scope). The hotspots are the categories of abiotic depletion (fossil fuel), global warming and ozone depletion, which cause major impacts due to the extensive consumption of natural sand resources in manufacturing the blocks. These categories are related to the use and burning of fossil fuels in engines used in river dredging to obtain the sand, internal transportation from the river mine area to the port, and port processing operations [38]. The other eight categories are influenced by the extraction of gravel and limestone sand. Mining and crushing entail creating large exploitation areas where the outer layer of the soil is modified and the fauna and flora are eradicated, while also generating microparticles harmful to humans, among other negative effects [51; 52]. Limestone sand with natural sand (used for the conventional block) contributes significantly in all categories evaluated. Using OS to replace these resources creates a reduction in such impacts ranging from 35% to 22%. The incorporation of waste  
Figure 5: Visual aspect of the block produced using iron-ore sand.  
with a granulometry similar to that of natural sand and gravel is one way to improve the performance of the block with tailings. Despite the reduction in environmental impacts associated with the use of ore sand in blocks, it is still necessary to determine the environmental impact of the transportation of aggregates to the manufacturing site in order to determine the environmental impact of using the ore sand.