The study simulated the Aeolian sand concrete damage process under wind-sand erosion using a sand-bearing wind-sand erosion test device. Then, different wind parameters were selected to study their damage failure influences on Aeolian sand concrete surfaces, and an orthogonal test was carried out for three factors: wind speed, sand carrying capacity, and angle of attack. The significant level and variance contribution rate of the angles of attack were the largest. The test results indicated that the damage failure arising from wind-sand erosion could be divided into three stages: the accelerated development stage, attenuation stage, and stabilization stage. During the accelerated development stage, the damage failure of the concrete surfaces was found to be relatively large, and obvious erosion pits were produced following the erosion. With the increases in action times, the process gradually developed into the attenuation stage, and then finally into the stability stage. The test results revealed that the damage failure of the Aeolian sand concrete surfaces which arose from the sand flow with 200 to 300 μm diameter sand was relatively serious.
In this paper, electrochemical impedance spectroscopy was used as non destructive technique (NDT) for studying the carbonation behavior of the concrete sample treated with migratory type of organic corrosion inhibitors. Concrete carbonation was achieved in carbonation chamber by maintaining 5% CO2 by volume, 60-70% relative humidity and 30 ± 2°C temperature for 90 days. The experimental results show that with progressive carbonation, porosity of the con-crete reduces and results in denser microstructure. The concrete surface treated with corrosion inhibitor C.I. 1 (amine – ether based) and C.I. 2 (2-aminobenzoic acid) shows the behaviour different form the control sample at the end of exposure conditions. Impedance results indicate that carbonation depth can be predicted by analyzing the high fre-quency arc of Nyquist plot. Also, both of the tested inhibitors were able to form a passive layer around the rebar surface and their efficiencies improved with time.
Magnesium phosphate cement was prepared with an MgO-containing byproduct (EL-MgO) obtained through the ex-traction of Li2CO3 from salt lakes, and was used to replace dead burnt MgO in magnesium phosphate cement (MPC) formulations. The properties of EL-MgO after calcination at various temperatures were investigated. Changes in pH, alternating-current impedance, and hydration-heat-release rate were assessed. Surface area and reactivity decreased while the degree of crystallization increased with increasing calcination temperature, resulting in longer setting times. The compressive strength of MPC prepared with EL-MgO calcined at 1000°C was 53.9 MPa after 1 day, which is high for quick-repair materials.