## 2 Materials and Methods  
### Raw Materials  
#### 2.1.1 Wastepaper Sludge Ash and Ground Granulated Blast-Furnace Slag  
The present study is in the continuity of a previous paper on mechanical performance of dry-mortars made with supplementary cementitious materials [23]. All the raw materials, i.e., supplementary cementitious materials are the same, namely wastepaper sludge ash (WSA) and ground granulated blast-furnace slag (GGBS). The microstructure analysis presented here is based on the mixtures whose mechanical strengths have been reported by [PERSON] et al. [23].  
On one hand, WSA is a residue collected from the paper recycling industry which comes from incineration of two types of raw materials: wastepaper sludge (55%) and, wood and wooden waste (45%). WSA is a grey powder and its median particle size D\({}_{50}\) = 11.68 \(\upmu\)m with binding properties. The oxides composition and some physical parameters of wastepaper sludge ash are presented in Table 1.  
The chemical composition varies and depends on the type of paper and wood combusted during incineration cycle but according to X-ray diffraction results, WSA contains mainly several crystalline phases. Those major crystalline phases are the following: Gehlenite Ca\({}_{2}\)Al\({}_{2}\)SiO\({}_{7}\), Calcite CaCO\({}_{3}\), Quartz SiO\({}_{2}\), Calcium oxide (lime) CaO and Calcium silicate Ca\({}_{2}\)SiO\({}_{4}\)[30].  
On the other hand, ground granulated blast-furnace slag which is designated as GGBS is a by-product from the blast-furnaces formed during the production of iron. As a matter of fact, granulated slag is attained from molten iron slag by quenching it in high pressure; then, it is further processed into a very fine white powder by drying and grinding, and the final product is called GGBS. Today, ground slag is used as the main constituent of certain types of cement (CEM II, CEM III and CEM V) and as an addition for high-performance longer-lasting concrete. A replacement of 70% is permitted by European standard NF EN 206-1. GGBS as a cement addition has interesting characteristics with a constant composition. The chemical composition and other physical parameters of GGBS are given in Table 1. All the physical properties of WSA and GGBS are reported by [PERSON] et al. [23].  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline
**Oxide (wt.\%)** & **CaO** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **MgO** & **K\({}_{2}\)O** & **TiO\({}_{2}\)** & **P\({}_{2}\)O\({}_{5}\)** & **Na\({}_{2}\)O** & **MnO** & **SO\({}_{3}\)** & **L.O.I** \\ \hline WSA & 50.70 & 19.90 & 10.40 & 1.17 & 2.49 & 1.01 & 0.60 & - & 0.44 & - & 0.66 & - \\ GGBS & 43.60 & 37.30 & 10.90 & 0.70 & 6.60 & 0.20 & 0.50 & - & 0.30 & - & 0.1 & - \\ \hline
**Parameters** & **Particle density (g/cm\({}^{3}\))** & \begin{tabular}{c} **D\({}_{50}\)** \\ **(um)** \\ \end{tabular} & \begin{tabular}{c} **pH** \\ **(-)** \\ \end{tabular} & \
\begin{tabular}{c} **SSA-BET** \\ **(m\({}^{2}\)/g)** \\ \end{tabular} &
\begin{tabular}{c} **adsorption cumulative surface area of** \\ **pores-BJH (m\({}^{2}\)/g)** \\ \end{tabular} & \\ \hline WSA & 2.87 & 11.68 & 11.17 & 2.12 & \multicolumn{4}{c}{1.372} \\ GGBS & 2.94 & 10.49 & 8.93 & 0.70 & \multicolumn{4}{c}{0.370} \\ \hline \end{tabular} Note: D\({}_{50}\) median diameter of particle size; SSA specific surface area.  
\end{table}
Table 1: Chemical composition of wastepaper sludge ash and ground granulated blast-furnace slag.