Characterization of cemented paste backfill pore structure using SEM and IA analysis

This paper presents a pore structure study conducted on different cemented paste backfill (CPB) samples using scanning electron microscopy and image analysis (SEM–IA). The SEM–IA approach was used to estimate three pore structure parameters: total porosity (n), pore size distribution (PSD), and pore space tortuosity (T). The influence of three binders and three types of water (one de-ionised and two sulphated) was also assessed after 14 and 92 days of curing. The evaluation of n by SEM–IA showed a decrease with curing time that was in accordance with the CPB strength increase. The PSD and the T were only slightly influenced by the water chemistry and the type of binder; the parameters evolved with curing time and were related to a decrease in pore size and an increase in tortuosity. Changes of the pore structure were more significant with sulphated mixing water and the OPC-slag binder. The methods and results presented here will be useful to predict some properties of CPB such as saturated hydraulic conductivity, water retention curve and effective diffusion coefficient.