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This paper presents research about a mixture design method of pavement concrete coblending rubber and fiber into ordinary concrete. Mechanical-based tests regarding the compressive strength, elastic modulus, splitting tensile strength, flexural strength, and four-point bending stiffness were conducted to evaluate the flexural toughness of concrete, and a slab-based three-point bending test was designed to evaluate the bending toughness improvement of the road pavement concrete slab. The results indicated that with the increase in single rubber content, the compressive strength and elastic modulus of concrete decreased continuously. The rubber concrete specimen remained relatively complete in appearance during destruction, showing the satisfied ductile failure characteristics to pavement usage with the optimal rubber content of 10%. After adding basalt fiber (BF) or polypropylene fiber (PPF), with the increase of fiber content, the bending stiffness of concrete decreased, the corresponding deflection of peak load increased continuously, and the bending deformation capacity of concrete could be significantly enhanced. Compared with the reference group, when the rubber content is 10%, and basalt fiber content is 0.5%–2%, the equivalent initial bending strength of fiber-reinforced rubber concrete is increased by 105.4%–164.4%. In general, BF is better than PPF in improving the toughness of rubber concrete, and the optimal dosage of BF is 1% of concrete volume in this test. When loaded to the limit load, the deflection of the basalt fiber–reinforced rubber concrete slab in the middle of the bottom span was about four times higher than that of the benchmark concrete slab, the bending deformation capacity and toughness of the basalt fiber–reinforced rubber cement concrete slab have been greatly improved. From the test results, the mixture design method of flexible pavement cement concrete based on rubber and fiber coblending was proposed, which contributes to the development of flexible materials for concrete pavement. [ABSTRACT FROM AUTHOR]

A magnetite mortar microwave-absorbing layer that could be applied to concrete pavement was studied to improve the deicing efficiency of roads in low-temperature conditions. The magnetite cement mortar (MCM) was prepared by using magnetite as the main absorbing material. The microwave absorption ability and heating characteristics of MCM with different magnetite contents were investigated. In addition, the mechanical and durability properties of MCM were studied. Furthermore, a microwave-absorbing layer was prepared and tested for outdoor field deicing. The result showed that adding magnetite effectively improved the mechanical strength and frost resistance of MCM, which could improve its load resistance and service life. Meanwhile, the microwave absorption ability of MCM was also improved with the increase of magnetite content. At the microwave frequency of 2.45 GHz, the average heating rate of MCM with 80% magnetite content was 2.27 times than that of ordinary cement mortar. In addition, the content of magnetite was positively correlated with the heat transfer ability of MCM. Magnetite conversion of microwave energy into heat energy could quickly transfer heat to the whole mortar system. The field deicing test verified the feasibility of efficiently deicing a magnetite mortar microwave-absorbing layer in low temperature conditions. [ABSTRACT FROM AUTHOR]

Repetitive loads result in increased irrecoverable strain and, consequently, fatigue cracking failure. Fatigue resistance is the prime factor controlling the service life of the concrete pavements. This research study utilized natural rubber latex (NRL) to enhance the mechanical strength and flexural fatigue resistance of normal concrete. The effect of influence factors, such as water to cement (w/c) and dry rubber to cement (r/c) ratios, on the compressive and flexural strengths and flexural fatigue behavior was studied. Normal and NRL concretes were subjected to compressive, flexural, and flexural fatigue tests. At all w/c ratios, a higher r/c ratio resulted in a lower compressive strength but higher flexural strength. The highest flexural strength was found at the optimum r/c ratios of 0.58, 1.16, and 1.73 for w/c=0.3 , 0.4, and 0.5, respectively. Concrete modified by NRL at the r/c ≤ optimum ratio had lower plastic deformation than normal concrete at the same applied flexural stress, hence, higher fatigue life (Nf). As a result, the NRL-concrete pavement at the optimum r/c ratio was found to have a thinner thickness than the normal concrete pavement for the same traffic load conditions at the same service life, which can reduce the operational cost. A cost-effective mix design method of NRL-concrete pavement with the optimized construction (operation and material) cost was also recommended. The outcomes of this research will facilitate the utilization of the NRL additive alternative to synthetic polymer for sustainable NRL-concrete pavement in Thailand and other Southeast Asian and South American countries, which are major global producers of natural rubber. [ABSTRACT FROM AUTHOR]

Due to greater durability and lower maintenance costs, concrete pavements are more competitive than asphalt pavements in areas where rigid pavements are required. To ensure the surface skid resistance of concrete pavement for driving safety, appropriate textures must be created on the concrete pavement surface. Common surface texturing treatments in Germany include exposed aggregate, grinding and grooving, and sealing methods. To investigate the influence of different surface texturing methods on the wearing resistance of concrete pavement, concrete pavement samples with six different surface textures were manufactured in this study. The advanced Aachen Polishing Machine (APM) was used to simulate the different polishing states on the extracted samples with 0, 16, 33, 100, 200, and 300 min of real-tire polishing effect. After each polishing stage, a series of surface characteristic tests was conducted to evaluate the wearing characteristics of pavement samples. The test results showed that different surface textures have different long-term polishing resistances. Of the texturing methods investigated, the exposed aggregate and sealing treatments provide the best long-term polishing resistance for plastic and hardened concrete, respectively. This research provided a comprehensive evaluation of and significant guidance on the selection of surface treatment methods for new construction of cement pavement and surface maintenance of hardened concrete pavement. [ABSTRACT FROM AUTHOR]

A new adhesive strength test (AST) was developed to determine the adhesive strength of joint sealant. A series of sealant thicknesses, displacement rates, and curing times was tested to determine proper AST testing parameters using self-leveling (SL) and non-self-leveling (NS) silicone sealants. A series of tests was conducted under varying moisture conditions. The results appeared to indicate that moisture may reduce adhesive strength. Drying-time tests were conducted to determine the approximate appropriate wait time between joint washing and sealant installation for 3.2 mm () and 9.5 mm () joints. A series of tests was also conducted on artificially aged sealants, which appeared to indicate that oven aging reduces adhesive strength for SL sealant. Non-self-leveling sealant, on the other hand, appeared to be largely unaffected by oven aging. Hot-water aging and freeze-thaw aging appeared to reduce adhesive strengths for both sealant mixtures. [ABSTRACT FROM AUTHOR]