Bury LED in concrete outside, how to protect
The heatSHRINK tubing idea is not so bad except for the rear lead exposure which you can pre-coat with adhesive ( Epoxy or PU or silicone )

I think the heatshrink will give a buffer to shrinkage of concrete for stresses on gold whisker wirebond but also might make it easy to poke thru the morter unless flush  YOu can always cut excess heatshrink after while protecting the lens in the process. But it does reduce the aperture cone angle significantly if beyond the curvature of the lens.

Just some other ideas...


Any kind of form will improve alignment.

Any kind of facial diffusion would make a bright brick more pleasing.

More ideas





My garden LEDs were just 4x1W on 4"x1" Al-clad, PCB powered by unregulated 14V with long 2V drop from AWG18 wire resistance and all 4S LEDs in parallel, shown above using a Schlumberger 200W external transformer formerly used to power external 12Vac 8W Halogen lamps. I modified it with bridge and cap. and covered hidden LEDs to prevent glare with cedar wood stained like the fence.