I am replacing the gl with poly lexan 1/4". Is there a mortar mix to replace the galzing? Aluminum frames?

The dap33 I was using is taking way too long. I have 30+ window panes to replace. the window is held in with clips; and I will have to seal in with elastine. (silicone). Is there a mortar type product to use instead of glazing? Ther average pane size is 47.25 by 16.5 inches. Each window has 2 of these (pull in type). Thanks