Have you defined system boundary of your process? System boundary constitutes of unit processes. These are the initial steps before creating LCA model in SimaPro software. If system boundary with functional unit is already defined then choose the suitable library for your process in SimaPro then start creating your process (from the processes option of inventory). For more details follow this link
SIMApro alredy includes the Econivent database. There you find LCIs for concrete and conretebased products. You can create copies and adapt them to your needs. E
I am working with GaBi software, but GaBi basically includes the Ecoinvent database. I think SimaPro also includes it. I have already performed such analyses with GaBi software. There are uploaded publications to my RG page on " LCA for concrete formulas" research topic. Best wishes, Viktoria