Laboratory Investigation of the Effect of Nano‑Materials on the Improvement of selec‎ted Properties of Self‑Compacting Geopolymer Concrete Containing Recycled Aggregates

3/16/2027 12:00:00 AM

Using recycled materials derived from construction an‎d demolition waste in the construction industry is a strategy to achieve sustainable development an‎d reduce the environmental challenges associated with stockpiling these wastes. However, concretes containing recycled aggregates often exhibit different characteristics compared to conventional concretes due to the inherent porosity of the adhered old mortar an‎d the formation of a dual interfacial transition zone (ITZ). In this study, the effects of adding nanoparticles an‎d micron-scale pozzolans on the properties of self-compacting geopolymer concrete (SCGC) containing recycled aggregates were investigated. In the experimental program, nine mix proportions were prepared. The mixes included one control specimen (containing 100% natural aggregates), one specimen with 50% replacement by recycled aggregates, an‎d other mixes with full (100%) utilization of recycled aggregates. To improve the properties of mixes containing recycled materials, various additives were used to partially replace the binder at specified dosages, including 10% microsilica, 4% micro-titanium, 4% micro-iron, as well as separate use of 2% nano-silica, nano-titanium, an‎d nano-iron. All specimens were tested for compressive strength at 28 an‎d 56 days, electrical resistivity, total porosity, water absorption, an‎d rapid chloride permeability (RCPT). The laboratory results showed that with 100% replacement of recycled aggregates, the 28-day compressive strength decreased by 12.6% compared to the natural-aggregate specimen, dro‎pping from 63.45 to 55.45 MPa. However, at 56 days, the use of 2% nano-silica resulted in a compressive strength of 64.80 MPa, indicating an 11.34% improvement compared to the additive-free mix containing 100% recycled aggregates. In the durability tests, the specimen with 10% microsilica exhibited the lowest permeability among all mixes, recording a porosity of 17.20% an‎d a total charge passed of 3853 coulombs. Moreover, the capillary water absorption test indicated that the mix containing 2% nano-iron registered the highest water uptake, with a value of 9.84 g/cm². The electrical resistivity test also showed that the presence of nanoparticles reduced the resistivity to below the 12 kΩ·cm range.

بتن ژئوپليمري خودتراكم , سنگدانه بازيافتي , نانوذرات , ناحيه انتقال فاز دوگانه

Self-Consolidating Geopolymer Concrete (SCGC) , Recycled Aggregate , Nanoparticles , Double Interfacial Transition Zone (ITZ)

parsa ghatan

Dr.AliAkbar Shirzadi Javid