关键词: 双向板, 地聚物砂浆, 碳纤维编织网, 抗弯加固, 力学性能, 传力机理

Abstract:

Textile reinforced mortar (TRM) strengthening is a method of using mortar as an inorganic adhesive to stick textile onto the surface of components to form a strengthening layer. It has advantages such as light weight, high strength, minimal change in cross-sectional dimensions, good high-temperature resistance, and excellent durability, and thus has gained widespread attention in recent years. TRM typically uses polymer-modified cement mortar as the adhesive, but the production of cement has high energy consumption and carbon emissions. To achieve the “dual carbon” goals, this paper proposed to replace cement with geopolymer, which has much lower production energy consumption and carbon emissions while offering mechanical properties similar to cement, thus forming a textile reinforced mesh-enhanced geopolymer mortar (TRGM) strengthening method.This paper employed carbon textile reinforced geopolymer mortar to strengthen two-way reinforced concrete slabs. The flexural performance tests and finite element analysis were conducted on the unstrengthened and strengthened slabs with different aspect ratios and different numbers of TRGM layers. The strengthening effect of TRGM, the contribution of bidirectional fibers to bearing capacity, and the force transmission mechanism of the strengthened slabs were investigated. The results show that TRGM strengthening can effectively improve the post-cracking stiffness and flexural carrying capacity of two-way slabs and inhibit crack propagation, especially the widthwise cracks. The strengthening effect of TRGM increases with the increase in the aspect ratio of the two-way slabs. The bearing capacity of the strengthened slab with one layer of TRGM was greatly influenced by the overlap of the textile and strengthening construction quality, which made the strengthening efficiency of one layer of TRGM lower than that of two layers. The overlap of the fiber mesh may affect the strength of the fibers, and the design should ensure that the fibers have sufficient overlap length. After the widthwise reinforcement yielding, the ratio of bending moment borne in the widthwise direction to the lengthwise direction gradually decreased, since the contribution of the longitudinal reinforcement and fibers to the bearing capacity gradually increased. As the mid-span deflection increases, the proportion of tensile force borne by the fibers shows a wave-like trend, first decreasing, then increasing, and subsequently decreasing again.

Key words: two-way slab, geopolymer mortar, carbon textile, flexural strengthening, mechanical performance, force transmission mechanism