Preparation and performance of acrylic mortar repair material modified suitably by nano-fiber and nano-particle in low-temperature for high-strength gain applications in construction

Nano -particles and nano -fibers have a marked effect on the physico-mechanical properties of polymeric mortar. In this study, to further enhance the mechanical properties of acrylic repair materials used in extreme environments (-25 degrees C or even lower), we added nano -particles (SiC, Al2O3, B4C, Si3N4, Fe2O3, SiO2), nano -fibers (CFs, MW-CNTs), nano -sheets (GNP, MOS2) and one homemade three-dimensional (3D) nano -fibers SiC-OH@APTES-g-CFs-COOH, respectively, to the polymeric mortar. We investigated how the dimensionality, content and type affect the compressive strength and flexural strength of the acrylic mortar repair materials. Acrylic mortar specimens were prepared by mixing methyl methacrylate binder, aggregates, initiator, accelerator and different nano -particles in a standard cement mixer, which is placed in standard molds of 40mm x 40mm x 160 mm and kept in -25 degrees C. Compressive and flexural strength of the acrylic mortar repair materials were determined at 1h, 1d and 10d of curing. The carbon fibers were treated with gamma-aminopropyltriethoxysilane (APTES), and the 3D nano -fibers SiC-OH@APTES-g- CFs-COOH were prepared. The Scanning electron microscopy (SEM) analysis indicated that a large number of SiC were uniformly and densely distributed on the surface of CFs. The mechanical strength results showed that almost all contents of nano -materials of any dimension used in this article could enhance the mechanical strength of the specimens. Notably, when 0.05 wt% SiC-OH@APTES-g-CFs-COOH was added, the compressive strength and flexural strength values of acrylic mortar specimens at 10d were improved by 41.16 % and 52.28 % than those of control specimens. The incorporation of 3D nano -fibers formed a mechanical engagement with the aggregates, which increased the contact area between the aggregates and 3D nano -fibers and the thickness of the contact layer inside the specimen, thus effectively transferring the stress when the specimen was subjected to the load, and enhance the interfacial properties between the substrate and the nanofillers. Among the explored nano -particles, the addition of Si3N4 could significantly improve the compressive and flexural strength of acrylic mortar. Compared with the control specimen, the compressive strength can be improved by 44.6 % and the flexural strength of acrylic mortar specimens can be improved by 76.2 % when the addition of Si3N4 was 0.3 % by weight. This article demonstrated the availability of nano -powders for improving the mechanical properties of polymeric mortar construction materials.