Airport runway pavements often undergo the direct impact of aircraft landings. For the purposes of designing the structure, it is of great importance to know about the dynamic response of the pavement and its behavior under impact loading. However, the dynamics and failure mechanisms of reinforced recycled aggregate concrete pavements subjected to impact loading are seldom explored in the literature. For this purpose, four reinforced recycled aggregate concrete pavements with different thickness and ratios of reinforcement, and one reinforced normal concrete pavement, were manufactured and tested under impact loading using the drop-weight impact frame system. The impact force characteristics, crack patterns, deformation responses, and strain developments of reinforced concrete pavements subjected to impact loading were evaluated and compared. The above-mentioned study revealed that with an increase in the reinforcement ratio, both the deformation and the steel strain were reduced. Increasing the thickness would reduce the degree of damage and the impact force of reinforced concrete pavement (RCP) but increase the deformation. The results show that under the same compressive strength, the dynamic performance of the reinforced recycled aggregate concrete pavement was worse than that of the reinforced normal concrete pavement because of its lower elastic modulus and weaker interfacial transition zone. The dynamic performance of reinforced recycled aggregate concrete pavement could be improved by increasing the thickness and reinforcement ratio. The use of recycled aggregate concrete (RAC) in RCP is a technically feasible application of the material within the scope of this experimental study.

To improve the utilization efficiency of dredged sand and alleviate the depletion of natural aggregate resources, ultrafine dredged sand (DS) was used as a fine aggregate replacement to prepare alkali-activated slag/fly ash concrete. The effects of DS and fly ash (FA) replacement rates on the workability and mechanical properties of the concrete were investigated. XRD, SEM, and MIP tests were conducted to analyze the hydration products, micromorphology, and pore structure, and the underlying modification mechanism of DS for alkali-activated concrete was clarified. The results show that, compared with the group without dredged sand, the 3 d, 28 d, and 90 d cubic compressive strengths of the group with 30% dredged sand increased by 8.35%, 9.3%, and 9.8%, respectively. Appropriate incorporation of dredged sand can optimize the pore distribution and microstructure, improve the compactness of the concrete matrix, and significantly enhance both the early and later strength of alkali-activated concrete. The 28 d compressive strength and splitting tensile strength of AASC both increase first and then decrease with the rising FA dosage. Moreover, the incorporation of fly ash exerts a remarkable enhancement effect on its later strength.