Geopolymeric and cementitious mortars for buildings: Comparison at the same strength class

Scriptie/Masterproef: Doctoral Thesis


The work deals with the study of geopolymeric and cementitious mortars with the same mechanical strength class (according to UNI EN 1504-3:2006) for construction applications.
In the first part, traditional cementitious mortars strengthened with fibres or textiles applied to masonry panels were tested and compared. Best results were obtained by reinforcing cement-based panels, since both the axial and diagonal strength were increased after the application of the strengthening material.
In the second part, geopolymeric and cementitious mortars belonging to R1 ≥ 10 MPa, R2 ≥ 15 MPa, R3 ≥ 25 MPa and R4 ≥ 45 MPa strength classes were tested and compared in terms of density, workability, dynamic modulus of elasticity, adhesive strength, porosimetry and water vapour permeability. Capillary water absorption, drying and restrained shrinkage, resistance to sulphate attack, corrosion behaviour of embedded black and galvanized reinforcements in chloride-rich solution and after carbonation were also investigated. In geopolymers, drying shrinkage is higher than that of cementitious mortars, but restrained shrinkage is lower due to lower modulus of elasticity. Pore dimensions affect water vapour permeability, more pronounced in geopolymers, and capillary water absorption, much lower in fly ash ones. The high alkalinity of geopolymers delays the achievement of the passive state in particular for galvanized steels, but after one month of curing they reach the same corrosion rates of those embedded in cementitious mortars. During chlorides exposure and after carbonation fly ash geopolymers offer the highest protection to embedded black bars. On the other hand, cementitious mortars maintain the lowest corrosion rates of galvanized steels.
The manufacture of one-part geopolymers by substituting the alkaline activators with biomass ash was also investigated. Results demonstrate that the K/Al molar ratio and the ash reactivity are key parameters to develop the mechanical strength.
Datum prijs2016
Originele taalEnglish

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