# Performance of Ore Sand as Aggregate for Interlocking Blocks
## 2 Materials and Methods
### Life Cycle Assessment
#### 2.3.1 Goal and Scope  
The life cycle assessment compared the environmental impacts of two sets of aggregates for the production of 60,000 interlocking concrete blocks with the same load capacity (functional unit). The first alternative corresponds to a conventional block produced with natural aggregates (gravel, sand, and limestone sand), and the second alternative (ore sand block) was produced by partial replacement of natural aggregates with OS.  
The LCA involved a cradle-to-gate analysis of the production of aggregates. The process of molding the blocks is the same for both mixtures; thus, the production process was not analyzed. Concrete blocks can have different applications (i.e., paving of roads and sidewalks, parking lots, and outside areas of houses); thus, the impacts related to use and end of life were not considered. The two systems studied are shown in Figure 3, and all emissions associated with energy and the production of raw materials are considered. The system for the ore sand block consists of (1) production of the gravel; (2) production of  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multicolumn{2}{c}{**Conventional Block**} & \multicolumn{2}{c}{**OS Block**} \\ \cline{2-5}  & **Weight (t)** & **Percentage (wt\%)** & **Weight (t)** & **Percentage (wt\%)** \\ \hline Natural Sand * & 98.2 & 51.4 & 85.1 & 44.5 \\ Limestone Sand * & 26.2 & 13.7 & - & 0.0 \\ Gravel * & 39.3 & 20.5 & 39.3 & 20.5 \\ Ore sand * & - & 0.0 & 39.3 & 20.5 \\ Cement (OPC) * & 27.5 & 14.4 & 27.5 & 14.4 \\ Water & 8.4 & 4 & 8.4 & 4 \\ Plasticizer Additive & 10.5 & 5 & 10.5 & 5 \\ \hline \hline \end{tabular}
* Percentage relative to the dry mass (cement and aggregates).  
\end{table}
Table 1: Mix ratios used to produce 60,000 interlocking concrete blocks.  
the natural sand; (3) transport of gravel and natural sand; and (4) transport of IOT sand. The ore sand was considered a waste product and thus was considered not to have any environmental impact associated with its production. The system for conventional blocks consists of (1) production of the gravel; (2) production of the natural sand; (3) production of limestone sand; (4) transport of gravel, natural sand, and limestone sand.  
An assessment of the environmental impact of transporting ore sand was carried out to determine the influence of the transportation distance of this material on the production of the blocks. Six distances (50, 100, 200, 400, 800, and 1600 km) were established for truck and train conveyance. Trains are normally used in Brazil to transport mining materials. The average diesel consumption for road transport is 1.9 \(\times\) 10\({}^{-2}\) L\({}_{\text{diesel}}\)/km.t, and the consumption for the freight rail system is 3.6 \(\times\) 10\({}^{-3}\) L\({}_{\text{diesel}}\)/km.t. These data were obtained from local companies that transport this material. Calculations involving the transportation of conventional aggregates were based on the average distance traveled by these products to the block factory: 10 km for gravel and limestone sand and 60 km for natural sand. Transportation of such materials is usually carried out by truck.