Optimization in cracking resistance and microscopic characteristics of high-performance concrete with full aeolian sand by a hybrid system of SAP, SRA, and steel fiber

  • JCR分区:

    影响因子:

  • High-performance concrete with aeolian sand (FA-HPC) can surmount the shortage of river sand to achieve environmental and energy conservation. However, the high risk of cracking limits the application of FA-HPC. Herein, concrete cracking behavior was investigated, and optimized by superabsorbent polymer (SAP), enhanced shrinkage-reducing admixture (ESRA), and steel fiber (SF) from a micro perspective. Meanwhile, the bonding degree of the SF-matrix is quantified via the SF pull-out test. In conjunction with the microscopic characteristics, including microscopic morphology, pores, microhardness, and solution properties, the synergistic mechanism of mitigation in shrinkage and structure cracking was revealed in the ternary system. The results show that the single SAP performed better shrinkage reduction and internal relative humidity (IRH) maintenance than the single ESRA. This modification was further enhanced by binary (SAP with ESRA) and ternary system (SAP, ESRA, SF). Besides, ESRA and SF were the main factors for strength enhancement with the discount effect of SAP, reaching an optimization of 125 MPa in a hybrid of 0.3%SAP, 3%ESRA, and 1 vol%SF. Whether used by single or hybrid, cracking resistance was elevated in unloaded and loaded conditions, exhibiting 78 % and 567 % enhancement in the ternary system, respectively. Meanwhile, SF altered the brittle fracture to the ductile mode of the FA-HPC and achieved strong bonding in the ternary system. Although the absorption capacity of SAP declined because of the ESRA adhesion, the mixing system significantly lowered the surface tension, supporting the optimization of shrinkage and IRH. Additionally, more hydration products and refined pore structures suppressed the generation and expansion of microcracks. A densified interface transition zone (ITZ) with high microhardness benefited the improvement of crack resistance.