Compressive strength at 1 day of Portland cement as a function of the microstructure of cement was statistically modelled by application of multi-block regression method. The observation X-matrix was partitioned into four blocks, the first block representing the mineralogy, the second particle size distribution and the two last blocks the superficial microstructure analysed by differential thermo gravimetric analysis. The multi-block method is used to identify the role of each part. The score vectors of each block can be analysed separately or together with score vectors of other blocks. Stepwise regression is used to find minimum number of variables of each block. The multi-block method proved useful in determining the modelling strength of each data block and finding minimum number of variables within each data block. Copyright © 2008 John Wiley & Sons, Ltd.