## 4 Discussion
Although Ecuador does not yet report specific data on local fibers in the tables presented, the analysis suggests untapped potential. A comparison with fibers used in Iraq, India, and Bangladesh shows that implementing fibers with high tenacity and low lignin content could be replicated in the region. That encourages future lines of research applied to native Ecuadorian fibers for stabilizing expansive soils. Table 10 shows that compared to industrial materials such as fly ash or silica fume, Ecuadorian industrial and agricultural byproducts show potential competitiveness if their composition is valorized. These ashes have already been successfully tested in India and Malaysia. Therefore, the results in this table reinforce the article's focus: There is a technical justification for promoting the use of Ecuadorian agro-industrial waste as a viable and sustainable alternative for improving expansive soils. In the sustainable techniques, a comparative matrix of sustainable materials used to improve expansive soils on the Ecuadorian coast was developed (see Table 11). A comparison index (_lc_) was used to quantify the influence of the improvement methods on the geotechnical properties of the soil: MDD, OMC, UCS, and observations of the CBR. The _lc_ index was calculated by dividing the value of the improved soil geotechnical property by the unimproved soil geotechnical property. The Ecuadorian case (see Table 11) stands out for using 10% rice husks and 40% recycled ceramics, increasing CBR from 8.92 to 34.6 under saturated conditions. This increase is comparable to that of countries such as Pakistan (CBR up to 15.4 with combined fibers) or Saudi Arabia (CBR of 40 with banana leaf ash and nano-silica), demonstrating that Ecuador can achieve competitive results with local waste. This finding suggests that it is unnecessary to resort to imported industrial additives to achieve significant improvements. Furthermore, it is noted that Ecuador has not yet reported UCS or MDD data, unlike countries such as India or Iran. That highlights a pending line of research that must be developed to complement the strength and dry density results with techniques adapted to Ecuadorian coastal soils. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline
**Additive** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **CaO** & **MgO** & **FeO\({}_{3}\)** & **K\({}_{2}\)O** & **TiO\({}_{2}\)** & **Na\({}_{2}\)O** & **SO\({}_{3}\)** & **P\({}_{2}\)O\({}_{5}\)** & **BaO** & **P\({}_{2}\)O\({}_{3}\)** & **MnO** & **LOI\({}^{1}\)** & **Mn\({}_{2}\)O\({}_{3}\)** & **Others** & **Reference** \\ \hline Fly ash & 59.12 & 18.30 & 12.07 & 1.49 & 3.87 & 1.02 & 0.49 & 1.17 & 1.65 & 0.39 & 0.12 & - & - & - & - & - & [20] \\ Fly ash & 59.83 & 30.48 & 1.74 & 0.86 & - & - & 6.91 & - & - & - & - & - & - & - & 0.18 & [60] \\ Fly ash & 57.47 & 15.36 & 3.32 & - & 4.71 & - & - & - & - & - & - & - & - & - & - & [133] \\ Bagasse or & 66.70 & 9.24 & 10.07 & 4.60 & 1.53 & 2.51 & 0.25 & 1.30 & - & - & 1.55 & 0.05 & 2.21 & - & - & [20] \\ sugarcane ash & 93.1 & 0.30 & 1.50 & 0.60 & 0.20 & 2.30 & 0.03 & 0.06 & - & - & - & - & 0.80 & - & - & [20] \\ Rice husk ash & 97.69 & - & 0.29 & - & 0.22 & - & - & 0.41 & - & - & - & - & - & - & - & [60] \\ Rice husk ash & 88.18 & 31.00 & 0.60 & 0.10 & 4.10 & 0.90 & 1.63 & 0.05 & 0.12 & - & - & - & - & - & - & [137] \\ Rice husk ash & 73.86 & 1.96 & 5.77 & 0.98 & 1.23 & - & - & - & - & - & - & - & - & 16.20 & [41] \\ Cement kil ash & 14.30 & 7.10 & 58.10 & 9.20 & 5.70 & 0.40 & 1.40 & 0.70 & 1.30 & - & 0.60 & - & 1.20 & - & [20] \\ Silica fume & 87.00 & 1.15 & 0.80 & 0.70 & 1.42 & 0.90 & - & - & - & - & - & - & 8.00 & - & - & [20] \\ Banana leaf ash & 17.54 & 4.08 & 47.31 & 1.47 & 3.87 & 16.92 & - & - & 2.69 & 3.14 & - & - & 0.28 & - & 2.70 & [91] \\ \hline \end{tabular} \({}^{1}\) Loss on ignition (LOI) for volatile elements.  
\end{table} 
Table 10: Chemical composition of additives for improving expansive soils (industrial and agricultural byproducts in percentage).