Just after some more general information regarding CEBs, especially the ratio of cement needed as an admixture and the potential of other less CO2 intensive materials like RHA to be partial or full replacements as stabilising/binding agents?
CEBs can be made with no cement. Unstabilized earth blocks can be used where they will not be subject to moisture. For stabilized blocks, a typical mix is 1:8 cement to aggregate. Leaner mixes can be used if a compression tester is available to verify strength. There are 3 standards: 1 MPa, 2 MPa and 3 Mpa compressive strength. At our Center we a use a mix of 1:11. 30% of the cement could be replaced with finely ground rice husk ash (RHA). Lime or lime/RHA can also be used as binders.