## 7 Conclusions  
In this work, the construction of trial sections based on hybrid stabilised soils with small amounts of lime, cement and nanomaterials was studied. For this purpose, an in-depth laboratory study was carried out to determine the physicochemical properties of the materials and the mechanical behaviours of the mixtures of stabilised soil. A structural design of the trial sections was carried out through a multilayer elastic model. Finally, the sections were built in a real-scale application, and their short and medium-term in situ properties were monitored.  
The following conclusions have been drawn from this study:  
The stabilisation of soils with nanosilica slightly increases the maximum dry density of the samples and slightly reduces their optimum water content. A reduction in the optimum water content implies a reduction in the consumption of natural resources (water, fuel, less CO2 emissions, etc.) to achieve the same or higher degree of compaction.  
The addition of nanosilica improves the bearing capacity of the stabilised soils as measured by the CBR index. The nanomaterial N1, composed of sodium silicate, shows a higher reactivity in combination with cement, increasing the unconfined compressive strength.  
The proposed hybrid stabilisation solution reduces the thickness of the control section by 37.5% and increases the bearing capacity measured in the number of equivalent axles by up to 25%.  
The sections built with N1 and N2&N3 show an improvement in the annual mean equivalent modulus of compressibility, with these sections showing a greater drop in bearing capacity during the rainy season.  
The results support the application of the developed alternative solutions with a hybrid stabilisation process due to their increased bearing capacity for rural and low-volume roads. However, due to the typical climatic conditions in Southern Spain, there is no evidence of effectiveness in the other conditions. In countries with high humidity and large temperature differences, the solution should be verified.  
As a general conclusion, the use of nanomaterials in percentages between 0.06 and 0.12% improves the mechanical behaviour of stabilised soils and allows a reduction in the thickness of the road layer, improving its general structural capacity, although there is a drop in capacity during rainy periods, which will be the subject of future studies.  
Conceptualization, F.A. and J.R.M.; methodology, J.R. and F.A.; investigation, J.L.D.-L. and M.C.; resources, F.A. and J.R.M.; data curation, J.L.D.-L. and J.R.; writing--original draft preparation, J.L.D.-L. and M.C.; writing--review and editing, M.C., J.R. and J.L.D.-L. and supervision, F.A. All authors have read and agreed to the published version of the manuscript.  
Figure 17: Annual average plate bearing test results.  
**Funding:** This work was financed by the project \"SLAKED-LIME REDUCTION ON EXPANSIVE SOILS BY MEANS OF NANOMATERIALS AND THE REUTILIZATION OF WASTED MATERIAL AND STABILIZING BY-PRODUCTS--ECARYSE. Ref. RTC-2017-62025\", granted by the call for \"FEDER/Ministerio de Educacion Ciencia y Universidades-Agencia Estatal de Investigacion\".  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Acknowledgments:** Call for Sub-modality 2.2. Pre-doctoral contracts UCO of the University of Cordoba's Research Plan 2020.  
**Conflicts of Interest:** The authors declare no conflict of interest.