Ignimbrite rock is a volcanic material located in the Arequipa region (Peru), and for centuries, it has been used as a construction material, giving a characteristic light pastel, white to pink color to the city of Arequipa, with white being the most common. In the present study, the potential use of three types of Arequipa raw materials (ignimbrite rock powder, calcined clay powder, and demolition mortar powder) as the main source of new binders or the manufacture of environmentally friendly mortars, without the addition of ordinary Portland cement (OPC) is discussed. In this work, an in-depth characterization of the materials used was carried out. The proposed fabrication route for geopolymeric materials was considered for the manufacture of binders and mortars using an alkaline solution of NaOH with values between 12 and 18 molar, as a trigger for the geopolymerization process. Geopolymeric mortars were obtained by adding a controlled amount of fine sand to the previously prepared mixture of binder raw material and an alkaline solution. Conventional OPC and geopolymeric mortars manufactured under the same conditions were mechanically evaluated by uniaxial compression tests at a constant compression rate of 0.05 mm/min and under normal conditions of temperature and atmosphere, where the most optimal values were obtained for 15 molar alkaline solutions of ignimbrite without the addition of aggregates, with values of compressive strength of 42 MPa and a modulus elastic of 30 GPa. The results revealed a significant increase in the maximum strength and modulus of elasticity values when the volumetric fractions of OPC are completely replaced with geopolymeric binders in the study conditions of this work, demonstrating the enormous potential of the ignimbrite rock and construction waste studied, as raw material of alternative mortar binders without the addition of OPC. With this work, the ignimbrite rock, of great value in the region and also found in other areas of the Earth’s geography, was characterized and valued, in addition to the calcined clay and demolition mortar of the region.

Demolition residues (bricks, mortars and concrete) were collected, separated, crushed, ground and sieved into powder. The powder obtained was mixed with sodium hydroxide solution of various molar concentrations (9, 12 and 15 molar) until workable plastic pastes were obtained. The pastes obtained were used as binders in geopolymeric mortars and pavers, which were evaluated physically, microstructurally and mechanically (at 14 and 28 days of curing). In parallel, and for comparison purposes, conventional Portland cement mortars and pavers were manufactured. The microstructure found in conventional and geopolymeric mortars and pavers was similar, presenting two well differentiated phases, a continuous one of binder and a discontinuous one of unconnected fine aggregate particles. In general, the geopolymeric materials manufactured presented less porosity than the conventional ones and their mechanical strength was lower, although sufficient for their application as type I pavers (according to the Peruvian technical standard - NTP 399.611).

This work presents interesting results on the manufacturing and mechanical response of new mixtures for geopolymeric mortars using soils collected from sites near the Khapia hill located in the Puno region (Peru). Four types of soils were collected and used as binder raw material within a geopolymeric mortar mixture with a binder: sand ratio of 1:3. In parallel and for comparative purposes, the mechanical response of conventional Portland cement mortars was manufactured and evaluated, with a binder: fine sand volumetric ratio also of 1:3. To obtain the geopolymeric mortars, the sodium hydroxide solution with a molarity of 12 was considered as the liquid phase. While for the conventional Portland cement mortar, water was used. For all cases, the liquid phase: binder ratio was 0.6. The mechanical results were variable, with maximum average mechanical strength values between 30.1 and 45.4 MPa for geopolymeric mortars and 37.4 MPa for conventional mortars. On the other hand, Young's modulus values were found between 5.9 and 10.4 GPa for geopolymeric mortars and 8.8 GPa for conventional mortars. Regarding the porosity estimated from real and apparent densities, values between 27.2 and 28.3 % were found for geopolymeric mortars and 30.2 % for conventional mortars. The microstructure found for both types of mortars studied was very similar, all mortars consisted of two well-identified phases, a continuous and homogeneous phase of binder (geopolymeric or Portland cement) that surrounded another dispersed phase of aggregate particles (fine sand).