Sealing around drainage trench

[chumley0312]

Does anyone know best way to seal these gaps in the drain trench around my conservatory. The narrow one I would have thought some clear silicone sealant but what about the larger gaps. Should I use sand and cement and them seal once dried or other way.

 

[noseall]

Does anyone know best way to seal these gaps in the drain trench around my conservatory. The narrow one I would have thought some clear silicone sealant but what about the larger gaps. Should I use sand and cement and them seal once dried or other way.

Use A tub of Geo-fix or similar