# Cleaner Design and Production of Lightweight Aggregates (LWAs) to Use in Agronomic Application
## 3 Results and Discussion
### Sintered Materials
#### 3.2.1 Chemical and Physical Properties
As can be seen, the aggregates based on Italian red clay (RC) presented moderate porosities, which varied in the interval of 22.16-39.19%. These values were related to the WA\({}_{\text{24}}\) values presented by these aggregates (Table 5), which ranged from 7.27% for RC to 19.46% for RCCBA. When analyzing this series, we were able to see how the addition of the pore-forming agent (BS) to the initial clay produced an increase in the porosity of the aggregate obtained (RCBS\({}_{\text{15}}\)) that was associated with an increase of WA\({}_{\text{24}}\) (19.01%). However, the addition of 10% FG or CBA glass caused a slight decrease in the associated porosity values, which were in accordance with the WA\({}_{\text{24}}\) values obtained. The decrease observed in the aggregate porosity may have been due to the glass phase provided by the FG or CBA, although the internal structure of open interconnected porosity was maintained. In the case of the series of aggregates obtained from the Spanish clay mixture (WBC), although the values of Po and WA\({}_{\text{24}}\) were higher (P\({}_{\text{o}}\) = 47.60-54.78%; WA\({}_{\text{24}}\) = 29.20-40.29%), the trend commented on in the previous series was maintained by the addition of glass or ashes. Finally, the high water absorption values that they presented together with the fact that the WB\({}_{\text{PG}}\) and WB\({}_{\text{CBA}}\) specimens complied with the limits established by the standard to be considered as light aggregates made these materials very interesting to be used for agronomic purposes. According to the results of Table 6, the highest value of crushing strength was presented by RC (9.6 MPa), followed by the aggregates of the same series RCBS\({}_{\text{15}}\), RC\({}_{\text{FG}}\), and RC\({}_{\text{CBA}}\) (5.4-6.2 MPa). This was directly related to its higher density and lower porosity. The rest of the aggregates presented low resistance values. In particular, the two materials mentioned above for their good aptitude for the use established in this investigation, WB\({}_{\text{CFG}}\) and WB\({}_{\text{CBA}}\), had values of 1.3 and 0.8 MPa, respectively, for this property, of the order of that declared for ARLITA Leca L (a commercial aggregate \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Aggregate Name** & \(\rho_{\text{B}}\)**, g/cm\({}^{3}\)** & \(\rho_{\text{rd}}\)**, g/cm\({}^{3}\)** & **WA\({}_{\text{24}}\)**, \%** & **V\({}_{\text{P}}\)**, \%** & **S, MPa** & **S/\(\rho_{\text{rd}}\)**, N/m-g** \\ \hline WBC & 1.34 & 1.92 & 29.26 & 30.2 & 2.6 & 1.4 \\ WBBS\({}_{\text{15}}\) & 1.25 & 1.83 & 40.29 & 31.7 & 1.0 & 0.5 \\ WB\({}_{\text{FG}}\) & 1.15 & 1.86 & 38.11 & 38.2 & 1.3 & 0.7 \\ WB\({}_{\text{CBA}}\) & 0.72 & 1.80 & 39.86 & 60.0 & 0.8 & 0.4 \\ RC & 0.81 & 2.32 & 7.27 & 65.1 & 9.6 & 4.1 \\ RCBS\({}_{\text{15}}\) & 1.34 & 2.19 & 19.01 & 38.8 & 6.2 & 2.8 \\ RC\({}_{\text{FG}}\) & 1.19 & 2.14 & 16.99 & 44.4 & 5.7 & 2.7 \\ RC\({}_{\text{CBA}}\) & 0.75 & 2.08 & 19.46 & 63.9 & 5.4 & 2.6 \\ \hline \end{tabular}
\end{table} 
Table 6: Technological properties of the aggregates: \(\rho_{\text{B}}\) = loose bulk density; \(\rho_{\text{rd}}\) = oven dry density; WA\({}_{\text{24}}\) = water absorption after 24 h immersion; V\({}_{\text{P}}\) = void percentage; S = single aggregate crushing strength. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Parameters** & **WBC** & **WBBS\({}_{\text{15}}\)** & **WB\({}_{\text{FG}}\)** & **WB\({}_{\text{CBA}}\)** & **RC** & **RCBS\({}_{\text{15}}\)** & **RC\({}_{\text{FG}}\)** & **RC\({}_{\text{CBA}}\)** \\ \hline Po (\%) & 47.60 & 54.78 & 49.00 & 51.73 & 22.16 & 39.19 & 30.75 & 36.41 \\ TIV (cm\({}^{3}\)/g) & 0.33 & 0.44 & 0.38 & 0.40 & 0.11 & 0.23 & 0.18 & 0.21 \\ TPA (m\({}^{2}\)/g) & 1.20 & 1.37 & 1.13 & 1.40 & 1.82 & 1.39 & 1.20 & 1.41 \\ \hline \end{tabular}
\end{table} 
Table 5: LWA total intrusion volume (TIV) and total pore area (TPA) by mercury intrusion porosimetry (MIP). used in gardening, horticulture, and roof insulation applications).