This study focused on the rutting characteristics of two typical hot-mix asphalt (HMA) overlays in airfield composite pavement under high tire pressure: asphalt concrete (AC) and stone mastic asphalt (SMA). To fulfill this purpose, accelerated pavement testing (APT) was implemented on the instrumented test field, and a series of laboratory tests, including density test, Hamburg wheel tracking test (HWTT), and uniaxial penetration test, were conducted based on 38 field drilled cores. The results from APT indicated that the shear flow was the main cause of rutting in the airfield composite pavement and the rutting only occurred within the HMA overlay. No densification was found from these two overlays. SMA overlay had more consistent rutting performance, higher shear strength, less uplift deformation and rut depth, and, therefore, higher antirutting potential compared with AC overlay. Furthermore, the bottom strain of SMA overlay was smaller at the beginning, but it increased as the loading cycles increase. Additionally, the rutting accumulation could be divided into two stages, and the first stage contributed more than 54% deformation to the total rutting. Tire pressure played a key role in the rutting of HMA overlay, and therefore higher tire pressure was recommended when studying airfield composite pavement’s rutting. Finally, the SMA overlay had cost advantage because of its longer service life.

Reflective cracking is a common distress in hot-mix asphalt (HMA) overlay. A test method that can provide comprehensive information about reflective cracking is thus needed. In this study, an apparatus named Joint Motion Simulation System (JMSS) was developed, which consists of two hydraulic servo-systems and a temperature chamber. A newly developed reflective cracking test method (NRCTM) based on JMSS was proposed, which is applicable for airport pavement. This method considers the influences of both traffic and thermal loads under controlled temperature conditions. Laboratory tests were conducted to verify both repeatability and sensitivity of the NRCTM. The tests results revealed a coefficient of variation that was lower than 13%, indicating that the NRCTM exhibited satisfactory repeatability. In addition, the method was sensitive to four factors: test temperature, combination of loads, compaction of specimen, and type of mixture. Moreover, three types of interlayer structures were evaluated with the NRCTM: geotextile, stress-absorbing layers, and atactic polypropylene modified linoleum. The geotextile performed better than the other two interlayer systems. Thus, the NRCTM can be used for measuring the reflective cracking in HMA overlay with acceptable repeatability and sensitivity.

The application of magnesium oxychloride cement (MOC) is promising, but its poor water resistance seriously hinders its development and application. In this paper, we describe a new type of MOC with excellent water resistance, prepared using fly ash and hexadecyltrimethoxysilane (HDTMS). SEM, XRD, FTIR, TG/DSC, and other microscopic-scale studies were conducted to investigate the mechanism underlying the water-resistance enhancement of the new MOC. It was found that adding 20% fly ash and 3% HDTMS can strengthen the water resistance of MOC while retaining high mechanical properties. In particular, the residual coefficient remained at 0.91 after 7 days of immersion. This is because these two additives, when used together, can increase the content of the gelling 5-phase of MOC, as well as optimize the pore structure of MOC.

Highfriction surface treatment (HFST) has been widely utilized by state departments of transportation (DOTs) to reduce friction related vehicle crashes. However, although many studies have been conducted to enhance the durability of HFST, limited information is available on the properties of the HFST epoxy–bauxite mortar. Although an HFST may contribute little to the pavement structural capacity, its epoxy–bauxite mortars have several distinguishing properties that may result in incompatibilities between the HFST and underlying pavement. Consequently, knowledge of the HFST epoxy–bauxite mortar properties is critical to ensuring its durability. This paper determined the physical and mechanical properties of epoxy–bauxite mortar for HFSTs. An empirical method was developed to estimate an approximate binder content. Comprehensive laboratory testing determined the properties, including density, Poisson’s ratio, coefficient of thermal expansion (CTE), dynamic modulus, and crack resistance. It was found that the HFST epoxy–bauxite mortar has a CTE significantly higher than that of hot-mix asphalt (HMA) mixtures and portland cement concrete (PCC). The HFST epoxy–bauxite mortar basically is a viscoelastic material with very low water-absorption ability and a dynamic modulus greater than that of a HMA mixture. The test results of fracture energy, tensile strength, and crack progression rate (CPR) consistently indicated that the HFST epoxy–bauxite mortar has very good cracking resistance.

To achieve the efficient utilization of magnesium slag, this study investigates the use of magnesium slag, fly ash, and metakaolin as partial substitutes for cement in cementitious materials. The reactivity of these materials is assessed based on the compressive strength of mortar. The response surface methodology is employed to explore the influence of material proportions on the strength performance of cement mortar. The mechanisms underlying strength development in the composite system are examined through XRD, SEM, TG-DTG, and BET analyses. Additionally, the effect of magnesium slag on the drying shrinkage properties of cement mortar is studied. The experimental results indicate that magnesium slag exhibits low reactivity and cannot be used alone as an active admixture. The optimal proportion of magnesium slag, fly ash, metakaolin, and cement is 10:10:10:70, achieving over 80% of the strength of pure cement mortar and approximately 1.5 times the strength of cement mortar containing 30% magnesium slag. Furthermore, magnesium slag helps mitigate the volume shrinkage caused by drying in cement mortar. Therefore, this study can facilitate the comprehensive utilization of magnesium slag in the construction sector, reducing its negative impact on the ecological environment.