STUDIES OF MODEL MACROSCOPIC-DEFECT-FREE MATERIALS .2. MICROSTRUCTUREAND OPEN POROSITY IN THE SYSTEM 4CAO AL2O3 FE2O3-4CAO 3AL2O3 SO3-HPMC-H2O

Model macroscopic-defect-free materials (MDFs) representing selected c ompositions in the system 4CaO.Al2O3.Fe2O3-4CaO.3Al2O3.SO3-hMPC-H2O ha ve been investigated by means of electron microscopy and mercury intru sion porosimetry. 'Smooth spatial flow' of unreacted grains into an in tergranular hydrated-aluminium-monosulfate-related (AFm-like) phase an d rigid linkage of clinker phase-intergranular mass-solidified polymer are demonstrated. Solidification of an intergranular AFm-like phase i n the presence of hpmc and pressure during syntheses causes partial el imination of pores; electron microscopy shows the remaining pores to b e isolated at the micrometre level. Pore size distributions reveal the role of pressure in packing the pores with diameter r > 100 nm. Caref ul control of the mixing and pressing of reaction mixtures results in porosities in the range typical of MDFs. A scheme interrelating the at omic- and particle-level phenomena is outlined, and includes formation of AI(Fe)-O-C crosslinks between cement clinker and polymer.