If I understand correctly, you need to develop a LCA inventory database for cement. Although many LCA software can be helpful in terms of providing guidance, you need to define the system for yourself. The very first step would be to sketch the life cycle in form of a system (flow diagram) starting from mining, manufacturing, process waste management (such as cement kiln dust (CKD), distribution, use and end of life (demolition of structures and possible land disposal or recycling). We can go through quite a detail discussion here, however, shortly, the most important issue would be to first identify emission sources at each and every step of the life cycle and quantify them. This will need considerable data on previously measured emissions (to air, water and soil) or alternatively you will need to measure them yourself (which I presume would not be quite an option in terms of costs unless you have the adequate funds for that). You can also use emission factors published by various sources such as the US EPA, data base provided by Sima-Pro software (a good one actually) and try to modify them for your country where the technology may or may not be different than US or Europe. For the distribution part you will have to see your national air quality control standards and data. I suggest you have a look at the SimaPro data base and see if you can find relevant data.