## 2 Materials and Methods
### Materials
#### 2.1.2 Reactive Powder-Based Concrete (RPC)  
Type 1 Bastion General Purpose cement, supplied by DINGO Cement Pty Ltd., Burwood, Australia, complying with _AS 3972-2010-General purpose and blended cements_[35] and silica fumes, supplied from Master Builders Solutions by BASF, Australia, were used as the binder materials. The silica fumes were grey in color, comprised of very fine, spherical particles and met the requirements of _AS/NZS 3582.3.2016-Supplementary cementitious materials. Part 3-Amorphous silica_[36]. An XRF analyzer was used to determine the chemical compositions of silica fumes and the relevant data were supplied by the manufacturer (Table 3). Processed 50 N silica sand, with a maximum particle size of 600 \(\upmu\)m, obtained from North Stradbroke Island, Australia and silica flour, which was white in color and supplied from Unimin Australia Ltd., Nyora, Australia, were used as the aggregate particles. With regard to the liquid components used in the RPC mixtures, _Glenium 51_ high range water reducer was the superplasticiser (SP) used which was based on the work reported by [PERSON] [6], along with normal tap water. Three RPC mix designs were initially selected according to literature precedents (see in Table 4). However, the initial mixing processes resulted in poor workability--hence, mix design combinations were refined (Table 4). An excess amount of water was added to the aggregate particles in order to achieve saturated surface dry (SSD) conditions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample ID**} & \multicolumn{2}{c}{**Sample Composition for**} & \multirow{2}{*}{**Sodium Silicate**} & \multirow{2}{*}{**8 M NaOH**} & \multirow{2}{*}{**Total Weight** (kg)**} \\  & **1 kg of FA- (Alkaline Solution/FA Ratio; Na\({}_{2}\)SiO\({}_{3}\)/NaOH)** & & & \\ \hline GP 01 & GP-0.40; 0.50 & 0.133 & 0.267 & 1.40 \\ GP 02 & GP-0.40; 1.00 & 0.200 & 0.200 & 1.40 \\ GP 03 & GP-0.40; 1.75 & 0.255 & 0.145 & 1.40 \\ GP 04 & GP-0.40; 2.00 & 0.267 & 0.133 & 1.40 \\ GP 05 & GP-0.40; 2.50 & 0.286 & 0.114 & 1.40 \\ GP 06 & GP-0.57; 0.50 & 0.190 & 0.380 & 1.57 \\ GP 07 & GP-0.57; 1.00 & 0.285 & 0.285 & 1.57 \\ GP 08 & GP-0.57; 1.75 & 0.363 & 0.207 & 1.57 \\ GP 09 & GP-0.57; 2.00 & 0.380 & 0.190 & 1.57 \\ GP 10 & GP-0.57; 2.50 & 0.407 & 0.163 & 1.57 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: GP paste mix design. \begin{table}
\begin{tabular}{c c} \hline \hline
**Compound** & **Component (wt. \%)** \\ \hline Al\({}_{2}\)O\({}_{3}\) & 0.70 \\ SiO\({}_{2}\) & 95.5 \\ CaO & 0.40 \\ Fe\({}_{2}\)O\({}_{3}\) & 0.30 \\ K\({}_{2}\)O & 1.00 \\ MgO & 0.50 \\ Na\({}_{2}\)O & 0.40 \\ Other & 1.20 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Chemical composition of silica fumes. Mixing times and the rate of mixing were reported to be the crucial parameters, especially, in achieving high performances. Several reports have described the mixing processes, where the dry materials that are needed to be initially machine mixed for a period of 3-5 min at low speeds, after which the liquids are required to be added and then machine mixed for about 5-10 min. However, these time periods are known to vary among the various studies [27; 38; 39; 40; 41; 42]. In addition, high energy machine mixers at shorter mixing times are proved to provide workable mixtures [6; 43]. In the present study, the mixing procedure of RPC formulations were very similar to the one reported by [PERSON] [6], who has also referred to a typical staged- mixing approach as previously published [44]. Here, the dry materials (cement, silica fumes, silica sand and silica flour) were measured and machine-blended using a _Breville_ mixer for 2 min at a working speed of 50 rpm until the dry materials reached homogeneous consistency. Subsequently, the super plasticizer (SP) and water were pre-mixed and added into dry mix. This was then machine-mixed for 30 min at 85 rpm until a workable mixture was obtained.