add some pepper!

Joking aside, more information is needed. What type of soil is it! Silt, Clay, sand , gravel , mixture? whats the density, SPTs, CBRs, shear strength, friction angle, what is the moisture content, percentage of fines, plasticity of fines, where is the groundwater level, what depth needs stabilisation,

Hi, thanks for the quick answer, I can not tell those data yet, becuase I only made a terrain reconnaissance and when I take a look I saw this problem, I asked about and they told me that in this palce use to exixt a lagoon, and about the depth probably 30 centemeters (could change depending of the tests). Thanks.

If you are building a road that you designed, you should be advocating for the owner to have proofrolls of subgrades and density tests for compaction..... If you are having both of those things done, you'll have a testing laboratory involved which will give you access to a Geotech Egr who can help with the recommendations you need. I'm usually the last person in the forum to tell people to hire a professional as I always assume people know that and are still coming here for tips..... but in this case (like Eirechch implied) I can tell you that there are a lot of different ways of solving this and finding the right one requires not just knowing about the soils themselves... but knowing a lot about the site, available time and resources, magnitude of the work, contractor's familiarity with the methods, available equipment, project priorities, amount of risk the owner is willing to have in whatever recommendations are issued, and the design itself...... I will say that although chemical stabilization is occasionally the right path sometimes..... it is FAR down my decision tree flow chart and it has to check a lot of boxes for me to go that way. I wouldn't even consider if I had a contractor who had never done it before.

Quote (Jhoel0630)

...I need to know how to stabilize a salty soil...about the depth probably 30 centimeters (could change depending of the tests).

...that in this place use to exist a lagoon...

You will need to know the depth of the poor soil that was the lagoon. It is likely much thicker than 30 cm, possibly several meters thick. If just the soil for the road base (30 cm +) is stabilized, the road AND the stabilized 30 cm base can (and likely will) settle into the poor soil below.

Like darthsoilsguy2, I rarely suggest calling in a specialist, but in this case an experienced geotechnical engineer is necessary. There are manufactured products such as geotextiles and geogrids designed for use with poor soils.

I worked in a coastal area with deep, poor soil, what I described above happens. Depth of settlement (over many years) sometimes measured in meters... and continuing.