*2.1. Materials*

The materials used in the study to fabricate cement mortar composite were ordinary Portland cement (OPC), natural aggregate (NA), recycled expanded glass aggregate (EGA), superplasticizer (SP), and nano titanium dioxide (nTiO2). OPC from Boral Australia Co. and in accordance with AS3972 was used as a binder and Sikament NN was used as a superplasticizer (SP) in the mix, which meets all requirements as per AS1478.1 for high range water reducing admixture. EGA with a particle size of 0.25-4 mm from EGT Co. is shown in Figure 1. The specifications of EGA are compliant with EN and DIN standards. Figure 2 shows a SEM image of the utilized EGA in this study. Table 1 demonstrates the physical, mechanical, and thermal properties of the EGA.

**Figure 1.** Expanded glass aggregate (EGA) with a di fferent grain size.



**Figure 2.** SEM pictures of the utilized EGA.

Crushed gravel with the maximum size of 4.0 mm and density of 2800 kg/m<sup>3</sup> was used as NA. The NA was subjected to the particle size distribution test to precisely replicate the distribution of NA for the replacement of EGA by volume in the cement mortar. The size distribution testing was completed in accordance with AS1012 and the results are found in Figure 3.

**Figure 3.** Size distribution of the natural aggregate and EGA.

Moreover, the mercury intrusion porosimetry (MIP) test was undertaken to measure the porosity as well as pore size distribution of the EGA. The MIP test results of the EGA are revealed in Figure 4. Nanoparticles titanium dioxide (nTiO2) purchased in the powder form from US Research

Nanomaterials, Inc. Table 2 demonstrates the properties of the nTiO2 as indicated by the manufacturer.

**Table 2.** The properties of the nano-nTiO2 (US Research Nanomaterials, Inc.).


**Figure 4.** Pore size distribution of the EGA.

## *2.2. Sample Preparation*

The mixes had a water to cement ratio of 0.4 and a sand to cement ratio of 3:1. Two set of mixes were prepared: the first set of mixes were fabricated by partial and full replacement of NA with EGA without inclusion of nTiO2. The designed mixes with 0%, 50%, and 100% replacement percentage of EGA implied with CS, E50, and E100, respectively. The second set of mixes was fabricated by partial and full replacement of NA with EGA and incorporation of 1% nTiO2. The designed mixes with incorporation of TiO2 and the EGA replacement percentage of 0%, 50%, and 100% defined as CT, E50T, and E100T, respectively.

To fabricate the mixes, the dry materials (cement and NA/EGA) were placed in the mixer and mixed on the low speed for 2.0 min. In the case of CT, E50T, and E100T mixes, the nTiO2 were sonicated for 15 min in the solution of water and superplasticizer (SP) [39]. Then the dispersed nTiO2/SP/water solution was added slowly to the mix and the materials were mixed for another 5 min. The mixes cast in 70 × 70 × 70 mm<sup>3</sup> cubes and demolded after 24 h. The samples were cured in the fog room at a constant temperature of 23 ◦C and in accordance with AS1012.8. Table 3 demonstrates the mix proportion of the samples. The abbreviations for labeling each mix are defined in a way that the letters C and E representing control sample and mortar sample containing EGA respectively and number after the letters presents the percentage of NA replacement with EGA into the mixture. The letter T demonstrates the presence of TiO2 in the mix. For instance, the E50T mixture represents the sample that contains 50% EGA and TiO2.


 525  233  5.8  1%

 0

E100T

 267

**Table 3.** Mix proportion of the samples (kg/m3) of mortar.

### *2.3. Experimental Tests*

The flow table test was undertaken on the fresh cement mortar samples in accordance to the AS2701 to measure the mixtures workability and consistency. Moreover, the density of the mixture was determined via the density test according to AS2701. To measure the water penetration of the specimens, the water absorption test was conducted in accordance with AS1012.21 at the age of 28 days. The compressive test was undertaken on the cube specimens with the size of 70 mm × 70 mm × 70 mm and in accordance with AS1012.9 at the age of 7, 14, and 28 days. For each test, three samples were tested and the average including the error bar were reported.

In this study, the thermal insulation property and heat transfer rate of cement mortar containing EGA was evaluated by measuring the surface temperature distribution using infrared thermal imaging camera. For this purpose, the specimens with the dimension of 70 mm × 70 mm × 30 mm were prepared and kept at about 27 ◦C for a few hours to allow all samples to achieve the same initial temperature. Then the samples were exposed to a heat source and the surface temperature distribution of the other side was captured by an infrared thermal camera for 15 min (Testo 872, Testo Australia). The thermal test was repeated for three times for each sample. Figure 5 illustrates a schematic diagram of the thermal test.

**Figure 5.** Infrared thermography test.

#### **3. Results and Discussion**
