Performance deterioration law of foam concrete in airport arresting system under seawater corrosion

To evaluate how an engineered material arresting system (EMAS) can be applied in island airports, the performance deterioration laws of foam concrete of the arresting system at high temperature, high humidity and high salinity were investigated. An integrated full (semi) immersion test device was designed, wherein the temperature, air flow, and water volume could be controlled automatically. The deterioration in the macroscopic performance, namely in terms of water absorption, deformation, crushing strength, and half crushing energy, of the foam concrete soaked in freshwater at 30 ℃, simulated seawater at 30 ℃ and 60 ℃, was analyzed separately. The microstructure of foam concrete was examined via X-ray tomography, and the changes in the phase type and content of foam concrete after the solution corrosion were analyzed via X-ray diffraction. Research result demonstrates that the foam concrete cannot satisfactorily resist the seawater corrosion. After the foam concrete is soaked in the freshwater at 30 ℃ for 90 d, the crushing strength decreases by 11.5%. After it is soaked in the simulated seawater at 30 ℃ and 60 ℃, the crushing strength drops by 19.9% and 52.1%, respectively. When it is fully immersed in the freshwater and simulated seawater at 30 ℃, the water absorption increases linearly with time and reaches approximately 280% at 90 d. When the foam concrete is soaked in the simulated seawater at 60 ℃, the water absorption increases rapidly and levels off at approximately 350% after 10 d. The internal porosity and average pore size of foam concrete are 70% and 2.0 mm, respectively. Moreover, the two-dimensional penetration depth is approximately 8.4 mm. Therefore, it is extremely easy for the foam concrete to undergo corrosion. In addition, the relatively large pores render the upward transportation of saltine water under the capillary action difficult, so the salt crystallization is not noted on the surface of foam concrete. The foam concrete is powdered seriously after several cycles of water absorption expansion and wind drying shrinkage. Solutions can reach the interior of the foam concrete, leading to reactions such as matrix softening, calcium dissolution, and ion corrosion, thereby accelerating the damage to the foam concrete's skeleton and lowering its crushing strength. In practical engineering projects, unit bodies of EMASs should not be struck by seawater and reef as far as possible. Furthermore, the unit body and foam concrete should be made waterproof such that the EMAS can last long and function effectively. 3 tabs, 14 figs, 33 refs.