*2.1. Materials and Mortar Specimens Preparation*

CEM II A-LL 42.5 R (limestone Portland cement, Rc (2 days) > 25.0 MPa, Rc (28 days) > 47.0 MPa, 3100–4400 cm2/g Blaine specific surface area) was provided by Buzzi Unicem (Barletta, Italy) and used for the preparation of the cement mortars [40]. Conventional sand (normalized) was characterized as clean, isometric and rounded in shape grains in the 0.08–2 mm size range (1660 kg/m3) and provided by Societè Nouvelle du Littoral, Leucate, France [41,42]. End-of-life tyre rubber (TR) (0–0.5 mm and 0.5–2 mm size range, 460 kg/m3 and 500 kg/m3, respectively) and recycled porous waste glass (PG) (0.5–2 mm size range, 300 kg/m3) were provided by Maltek Industrie S.r.l., Terlizzi, Bari, Italy. PG is a sodium calcium silicate glass (71% SiO2, 9% CaO, 14% Na2O, 3% Al2O3, 2% MgO, 1% K2O) obtained from separate collection and separation of municipal and industrial solid wastes. Preliminary cleaning and crushing of the raw materials is followed by the addition of a porosizing agent at temperatures of 900–1300 ◦C, which induces a controlled porosity of the resulting beads, thus showing a specific weight in the 200–900 kg/m3 range. TR and PG were added as partial and/or total replacement of the conventional aggregate, which was made on a volume basis rather than on a weight basis due to the low specific weight of both waste materials. In the present case, the total volume of aggregate was set at 500 cm3 in order to preserve an acceptable workability of the mixture. For this purpose, another sand reference (sand, sample 2) with the same aggregate volume (500 cm3) and with a 0.5–2 mm sand size range (1880 kg/m3) was prepared. Tables 1 and 2 report the aggregate types used for the mortar preparation and the composition of the conglomerates. In the present case, the composites were prepared with a water/cement ratio equal to 0.5, specifically with 225 g of water and 450 g of cement; dosages that were chosen according to the standard protocol [41] for the normalized mortar preparation, showing a plastic behavior. After the mixture, the rheology of the fresh mixtures was evaluated by the flow-test [43]. The mortars were placed inside a truncated cone shape ring. After demolding, fifteen hits in fifteen seconds were applied. Flow data were calculated through the following empirical equation after evaluation of the diameters of the mixture before (*Di*) and after (*Dm*) the test:

$$\%flow = \frac{\left[\left(D\_m - D\_i\right)\right]}{D\_i} \ast 100\tag{1}$$

The percentage increase of the diameter of the non-consolidated sample over the base diameter represents the flow of a specimen.

Successively, all the specimens were molded in the form of prisms (40 mm × 40 mm × 160 mm) for the flexural and compressive tests and cured in water for 7, 28, 60 and 90 days after demolding [41]. Moreover, the specimens were molded in the form of cylinders for thermal (ϕ = 100 mm; H = 50 mm) and impact resistance (ϕ = 150 mm; H = 60 mm) tests and cured in water for 28 days after demolding.


**Table 1.** Mortars composition.

Porosimetric measurements of the resulting mortars were carried-out by Ultrapyc 1200e Automatic Gas Pycnometer, Quantachrome Instruments, Boynton Beach, FL, USA. In this respect, helium gas penetrates the finest pores of the material and the results were the average of three measurements performed on three specimens of the same type (see Table 2).

**Table 2.** Type, aggregate composition, specific weight ρ and porosity of the cement mortar specimens. Samples prepared with 225 g of water and 450 g of cement. TRf = fine tyre rubber, TRc = coarse tyre rubber, PG = porous glass.

