# Mechanical and Physical Characterization of Papercrete as New Eco-Friendly Construction Material
## 2 Materials and Specimens Preparation  
Waste paper and pulp used as recycled components in the papercrete specimens tested were derived as follows.  
Waste paper was a common printed office paper that was first of all reduced into small pieces by using a paper cutter. Then, the shredded paper was soaked in water for 24 h and finally placed overnight in a ventilated oven at 50 \({}^{\circ}\)C in order to eliminate extra water content. At the end of this process, the paper was submitted to grinding by using a blender to obtain the required size.  
The pulp used derived from the separation stage of the paper manufacturing process, resulting in a gray color and extremely humid. Before being added to the mortar, it was subjected to drying, mixing, and homogenization process. The drying process was conducted in a ventilated oven for a night at a temperature equal to 50 \(\pm\) 5 \({}^{\circ}\)C to extract the excess humidity, followed by subsequent cooling at room temperature (23 \({}^{\circ}\)C). Once the material was removed from the oven, its dry conditions were verified by weight method: the aggregate was weighed after 24 h and it was observed that there were no variations in the mass [20].  
Figure 1 shows the recycled paper in the form of waste paper and pulp before the drying process (Figure 1a), and after grinding and drying (Figure 1b). The grinding of the waste material was performed in a ball mill operating at 30 rotations per minute.  
Once the recycled paper components were ready, papercrete specimens were prepared by mixing the following components:  
* portland cement CEM III/A 32.5 R LH [21], with a compressive strength of 32.5 MPa assessed at 28 days of age;
* natural aggregates in a range between 0 and 4 mm [5] used for better packing of the incorporated mortar and for increasing mechanical strength reducing porosity [22];
* tap water in a quantity able to guarantee a water/cement ratio of 0.5, allowing appropriate mixture workability;
* waste paper and pulp prepared as previously described, added in different volumetric ratios.  
All specimens were placed in appropriate molds and aged for 28 days in a controlled humidity ambient with a temperature of around 20 \(\pm\) 2 \({}^{\circ}\)C, considering that the mortar fabrication temperature may influence the technical properties of the aged mortar [23].  
As previously stated, the main research objective is to evaluate the effects of a partial substitution in the cementitious mortars of waste dry paper (named 'PAPER' specimens) or pulp ('PULP' specimens). To this scope, three different volumetric percentages for each recycled paper type have been considered: 2%, 5%, 10%. In addition, also specimens made only with cement have been cast as reference for the other papercrete specimens considered (indicated as 'REF' specimens). Future development will be focused on aging tests in order to study the behavior of the material under different humidity and temperature conditions that also simulate extreme climates. Table 1 summarizes the percentage of the components considered.  
For each volumetric percentage, a triplet of prismatic specimens was prepared, having dimensions 160 mm \(\times\) 40 mm \(\times\) 40 mm. Totally, 21 specimens were prepared: one triplet for 'REF' specimens, 3 triplets for 'PAPER' specimens, and 3 triplets for 'PULP' specimens. Prismatic specimens were subjected at first to flexural tests. Then, on the resulting two halves compression tests were conducted. In addition, a series of prismatic specimens was tested as well for capillary water absorption. In order to measure the thermal conductivity,  
Figure 1: (a) Pulp and waste paper utilized. (b) Pulp after grinding and waste paper after drying.  
7 specimens having dimensions 300 mm \(\times\) 300 mm \(\times\) 20 mm were prepared (1 reference specimens, 3 with different waste paper percentage, and 3 with pulp). As an example, Figure 2 illustrates prismatic specimens before flexural tests.