Filling a Channel in Screed Floor Help, advice, information, answers and tips on all types of flooring from laminate and carpet to timber and vinyl

[skiddymark]

HI folks
I have a channell in my bathroom screed floor that i have used to sink heating pipes. The channel is about 4' by 1' deep.Which is the best fill option? I was considering self levelling compound but maybe sharp sand a cement is the best way to go?

Regards Skiddymark