If the dealing is done as per the following pattern:
(1) The total price of cement (by fixing rate) is paid in advance.
(2) And the date and month for receiving the cement is fixed.
(3) And the quality of the cement has been fixed (it can be fixed by determining company brand).
(4) The place where it is to be received is fixed (i.e. whether you would receive it from the shop or the shopkeeper shall deliver it to you). All these points were discussed in clear-cut words and the dealing was finalized and in the same meeting full payment was done. This is bai’ salam in the terminology of Shariah. This transaction is lawful. It has been mentioned there in Bahishti Zewar, Vol. 5, study it carefully.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband