Wuman Zhang

1. The rapid growth of air travel has heightened the demand for robust airport safety measures. Boeing statistics indicate that between 2013 and 2022, 43% of flight accidents occurred during takeof...

In order to evaluate the feasibility of surface coatings in improving the performance of RCC under salt spray conditions, sodium silicate (SS), isooctyl triethoxy silane (IOTS), and polyurea (PUA) were used as surface coatings to prepare four types of roller−compacted concrete (RCC): reference RCC, RCC−SS, RCC−IOTS, and RCC−PUA. A 5% sodium sulfate solution was used to simulate a corrosive marine environment with high temperatures, high humidity, and high concentrations of salt spray. This study focuses on investigating various properties, including water absorption, abrasion loss, compressive strength, dynamic elastic modulus, and impact resistance. Compared to the reference RCC, the 24 h water absorption of RCC−SS, RCC−IOTS, and RCC−PUA without salt spray exposure decreased by 22.8%, 77.2%, and 89.8%, respectively. After 300 cycles of salt spray, the abrasion loss of RCC−SS, RCC−IOTS, and RCC−PUA reduced by 0.3%, 4.4%, and 34.3%, respectively. Additionally, their compressive strengths increased by 3.8%, 0.89%, and 0.22%, and the total absorbed energy at fracture increased by 64.8%, 53.2%, and 50.1%, respectively. The results of the study may provide a reference for the selection of coating materials under conditions similar to those in this study.

The deterioration of Portland cement pervious concrete (PCPC) subjected to wet-dry cycles in the simulated acid rain solution was investigated; 4% silica fume (SF) and 8% fine aggregate (FAG) were used to replace part of cement and the coarse aggregates (weight by weight), respectively. The wear resistance, the compressive, and flexural strength of PCPC were measured. The results show that after 12 wet-dry cycles in acid rain solution the compressive strength and the flexural strength of control PCPC are decreased by 30.7% and 40.8%. The final compressive strength of PCPC with 4% SF and PCPC with 8% FAG is increased by 6.9% and 30.3%, and the final flexural strength is increased by 25.4% and 72.3%, respectively. The wear loss of PCPC is decreased by 58.8% and 81.9% when 4% SF and 8% FAG is added to PCPC, respectively. The microstructures of PCPC with wet-dry cycles are also discussed.

Purpose: Ethylene glycol (EG) solution is a common deicing fluid of the aircrafts. Roller compacted concrete (RCC) used in the runway and the parking apron will be subjected to freeze-thaw cycles in EG solution. The purpose of this study is to find whether RCC can be damaged by the action of freeze-thaw cycles or long-term immersion in EG solution. Design/methodology/approach: Freeze-thaw cycles test and immersion test in EG solution by weight were used to accelerate the degradation of RCC. A compression test and a three-point bending test were carried out in the laboratory to evaluate mechanical properties of RCC. The changes of microstructure were monitored by using scanning electron microscopy and energy-dispersive X-ray analysis. Findings: The results show that RCC specimens have little weight change in both freeze-thaw cycles test and immersion test. The dynamic modulus of elasticity, the compressive strength and the flexural strength of RCC with 250 freeze-thaw cycles in EG solution are decreased by 4.2, 15 and 39 per cent, respectively. The compressive strength is decreased by 35 per cent after 12 months of immersion in EG solution. Micro-cracks occur and increase with the increase in freeze-thaw cycles and immersion test. Originality/value: The mass ratio of the elements in the crystal is very close to the proportion of elements in CaC₂O₄ (C:O:Ca = 1:1.26:1.6). More attention should be paid to using EG in practical engineering because both the freeze-thaw cycles and the complete immersion in EG solution damage the mechanical properties of RCC.