## 3 Results
### Impact of Herbicide Treatment on the Construction Materials  
In the first trial (1998 and 1999), of the three chemical treatments tested, only glyphosate caused detectable mineralogical alteration of the schist samples, triggering the disappearance of vermiculite (Table 5), as the signal disappeared at 1.4 mm in the X-ray diffractograms at the same time as the signal increased by around 1.0 mm. Glyphosate can cause the complexation of iron and aluminum, both of which are present in vermiculite; if this occurs, it would be detected by a change in the interlaminar spacing of the vermiculite, which would shift from 1.4 mm to around 1.0 mm, overlapping with the signal of biotite and muscovite. No mineralogical changes were detected in granite after the application of the chemicals. Both physical infrared and burning treatments caused notable mineralogical changes in schist, such as the disappearance of kaolinite and vermiculite (Table 5), as indicated in the X-ray diffractograms. The high temperatures (above 800 \({}^{\circ}\)C) reached in both treatments led to the dehydroxylation of kaolinite and the loss of water from the interlaminar space of the vermiculite. Regarding the mortars, none of the treatments caused mineral alterations (Table 5). This is probably due to the fact that the mortars are very hardened, with (as indicated in Section 3.1) all the lime (CaO) converted into calcite (CaCO\({}_{3}\)), a thermally highly stable mineral. Regarding the salt content, we expected an increase in the ammonium salt after treatment with glyphosate and glufosinate-ammonium and an increase in the formation of sulphates after the application of sulphosate; however, none of these changes occurred. Before and after the application of the three chemical treatments, the ion contents were low, and no changes were detected (Table 5). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & **I** & **B** & **G** & **S** & **G-a** & **O** & **O. v.** & _T. z._ & _T. v._ \\ \hline \multirow{3}{*}{Cl\({}^{-}\)} & Schist & n.c. & n.c. & – & – & + & – & – & – \\  & Granite & n.c. & n.c. & – & – & – & + & – & – & – \\  & Mortar & n.c. & n.c. & – & – & – & + & – & – & – \\ \hline \multirow{3}{*}{NO\({}_{3}\)\({}^{-}\)} & Schist & n.c. & n.c. & – & – & – & + & – & – & – \\  & Granite & n.c. & n.c. & – & – & – & + & – & – & – \\  & Mortar & n.c. & n.c. & – & – & – & + & – & – & – \\ \hline \multirow{3}{*}{SO\({}_{4}\)\({}^{-2}\)} & Schist & n.c. & n.c. & – & – & – & + & – & – & – \\  & Granite & n.c. & n.c. & – & – & – & + & – & – & – \\  & Mortar & n.c. & n.c. & – & – & – & + & – & – & – \\ \hline \multirow{3}{*}{HCO\({}_{3}\)\({}^{-}\)} & Schist & n.c. & n.c. & – & – & – & n.c & – & – \\  & Granite & n.c. & n.c. & – & – & – & + & – & – & – \\  & Mortar & n.c. & n.c. & – & – & – & + & – & – & – \\ \hline \multirow{3}{*}{PO\({}_{4}\)\({}^{-3}\)} & Schist & n.c. & n.c. & – & – & – & - & n.c. & n.c. & n.c. \\  & Granite & n.c. & n.c. & – & – & – & - & n.c. & n.c. & n.c. \\  & Mortar & n.c. & n.c. & – & – & – & - & n.c. & n.c. & n.c. \\ \hline \multirow{3}{*}{NH\({}_{4}\)\({}^{+}\)} & Schist & n.c. & n.c. & – & – & – & n.c. & n.c. & n.c. & n.c. \\  & Granite & n.c. & n.c. & – & – & – & n.c. & n.c. & n.c. & n.c. \\  & Mortar & n.c. & n.c. & – & – & – & n.c. & n.c. & n.c. \\ \hline \multirow{3}{*}{Minerals} & Schist & +(d.k.d.v.) & +(d.k.d.v.) & +(d.v.) & – & – & – & – & – \\  & Granite & n.c. & n.c. & - & – & – & – & – & – \\ \cline{1-1}  & Mortar & – & – & – & – & – & – & n.c. & n.c. \\ \hline \hline \end{tabular}  
* I: infrared, B: burn, G: glyphosate, S: sulphosate, G-a: glufosinate–ammonium, O: oxyfluorfen, _O. v._: Origanum vulgar L, _T. z._: Thymus zygis  
Loefl. ex L, _T. v._: Thymus vulgaris L.  
\end{table} 
Table 5: Changes in the ion content and the mineral composition. \(+\): change detected; \(-\): no change detected; n.c.: not considered; d.k. : disappearance of kaolinite; d.v. : disappearance of vermiculite. After one year, none of the three chemical treatments caused further mineralogical changes.