Applications of Allophane in Mortars and Asphalts: Predictive Modeling and Improvement of Physical-Mechanical Properties

Allophane, a nanoporous micromaterial of volcanic origin, can improve impermeability, strength, and durability. In an initial stage involving mortars, allophane was characterized using SEM and TEM microscopy, which revealed its amorphous nature. An optimization model based on cubic splines implemented in Python was developed and applied to mortar mixtures (prepared according to ASTM C270 and NTE INEN 2518 standards), which allowed the identification of allophane dosages capable of reducing water absorption by up to 23.7% compared to the standard (0.5% additive in ratio cement to sand 1:5, after 28 days of curing). The waterproofing tests were conducted in accordance with ASTM C1585. The model also predicted an optimal dosage of 0.41%, demonstrating the usefulness of integrating predictive modeling with experimental validation. In a second stage, concerning asphalts, the impact of allophane on asphalt mixtures was evaluated using a conventional design mix with 95.1% crushed stone aggregates and 4.65% AC-20 asphalt, modified with 0.25% of allophane. The mixtures were characterized by indirect traction tests—rigidity modulus at different temperatures (10˚C, 20˚C, and 40˚C), aging in accordance with AASHTO R-30 standards, as well as Marshall stability and flow tests, volumetric properties, Cantabro wear, FTIR, and TGA. The results show that allophane increases the strength and extends the service life of asphalt mixtures by 28.92 ± 2% compared to conventional mixtures, improving adhesion, cohesion, and compatibility. Overall, these findings confirm allophane as a versatile and promising nano-additive for optimizing mortars and asphalts, providing sustainable and high-performance solutions in the construction industry.