Impact Of Traffic Characteristics and Pavement Surface Condition on Noise Level for Rigid Pavement

The proper design of a road’s surface layer can result in pavements that are not only better in terms of ride comfort and safety, but also in terms of noise reduction. The use of low-noise pavements may be an effective measure to reduce the acoustic pollution generated by road traffic This study aims to consider the effect of changed pavement features on the noise level. Tire/pavement noise is a major contributor to traffic noise at highway speeds. The effects of pavement properties, including air-void content, gradation properties, roughness, texture, pavement surface condition are major contributors to traffic noise at highway speeds. As the overall texture and IRI, increase noise levels. The results showed that greater air void content decreases the level of high-frequency noise.

Experimental Study on Strength of Pervious Concrete by Using Fine Aggregate

Pervious concrete is a special type of concrete, which consists of cement, coarse aggregates, water and if required and other cementations materials. As there are no fine aggregates used in the concrete matrix, the void content is more which allows the water to flow through its bodyThe main aim of this project was to improve the compressive strength characteristics of pervious concrete. But it can be noted that with increase in compressive strength the void ratio decreases. Hence, the improvement of strength should not affect the porosity property because it is the property which serves its purpose. In this investigation work the compressive strength of pervious concrete is increased by a maximum of 18.26% for 28 days when 8% fine aggregates were added to standard pervious concrete Keywords: W/C ratio, pervious Concrete, sugarcane bagasse’s ash, rice husk ash compressive strength, fine aggregates

Reinforced Concrete Structure Performance in Marine Structures: Analyzing Durability Indexes to Obtain More Accurate Corrosion Initiation Time Predictions

This paper presents a comparison of six index properties collected during durability inspections of five Mexican seaports. Typical durability indicators such as compressive strength, saturated electrical resistivity, ultrasonic pulse velocity, percent total void content, capillary porosity, and chloride concentration profiles were analyzed to obtain empirical correlations with the non-steady-state chloride diffusion coefficient. These indices were compared to determine correlation coefficients that are the most important for obtaining better corrosion initiation forecasting. Two models of corrosion initiation time (ti) were used: Fick’s second law of diffusion and the reported UNE-83994-2 (Spanish Association for Standardization, UNE) in which electrical resistivity was used to calculate concrete service life. The data from both models were cleaned using correlated variables, and the initial variables were compared with ti. The main result achieved was the verification of the feasibility of using correlations of variables to clean unnecessary data in order to calculate ti. Additionally, electrical resistivity was identified as one of the main durability indexes for in-service concrete structures exposed to marine environments. This is important because electrical resistivity is a non-destructive and reliable test that can be measured both in the laboratory and in the field very easily.

Ultrasonic Evaluation of Porosity in Out-of-Autoclave Carbon Fiber–Reinforced Polymer Composite Material

Ultrasonic longitudinal wave propagation is studied in out-of-autoclave (OoA) carbon fiber–reinforced polymer composite material with varying levels of porosity contents. A combination of cure pressures and a solvent is used to produce specimens with void contents in the range of 0% to 22%. Ultrasonic measurements are made in through-transmission mode, and the data is processed to study various aspects of wave interaction with porosity in OoA specimens. The specimens with a wide range of void contents have enabled the study of broader trends of ultrasonic center frequency, wave velocity, and attenuation with respect to porosity. Results show ultrasonic center frequency and wave velocity are decreased linearly as the void content increases. The relationship of ultrasonic wave attenuation can be approximated by a logarithmic relationship when considering the full range of void content studied. Strength measurements of specimens with varying void contents are made using the flatwise tensile (FWT) test. It is observed that the strength rapidly decreases with increasing porosity. Correlations made between FWT strength, ultrasonic wave velocity, and attenuation are best described by logarithmic relationships. The data shows a potential for inferring strength knockdowns due to the presence of porosity based on ultrasonic measurements.

Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

Effect of Cyrtostachys renda Fiber Loading on the Mechanical, Morphology, and Flammability Properties of Multi-Walled Carbon Nanotubes/Phenolic Bio-Composites

This research focuses on evaluating the effect of Cyrtostachys renda (CR) fiber and the impact of adding multi-walled carbon nanotubes (MWCNT) on the morphological, physical, mechanical, and flammability properties of phenolic composites. MWCNT were supplemented with phenolic resin through a dry dispersion ball milling method. Composites were fabricated by incorporating CR fiber in 0.5 wt.% MWCNT-phenolic matrix by hot pressing. Nevertheless, the void content, higher water absorption, and thickness swelling increased with fiber loading to the MWCNT/phenolic composites. The presence of MWCNT in phenolic enhanced the tensile, flexural, and impact strength by as much as 18%, 8%, and 8%, respectively, compared to pristine phenolic. The addition of CR fiber, however, strengthened MWCNT-phenolic composites, improving the tensile, flexural, and impact strength by as much as 16%, 16%, and 266%, respectively, for 50 wt.% loading of CR fiber. The CR fiber may adhere properly to the matrix, indicating that there is a strong interface between fiber and MWCNT-phenolic resin. UL-94 horizontal and limiting oxygen index (LOI) results indicated that all composite materials are in the category of self-extinguishing. Based on the technique for order preference by similarity to the ideal solution (TOPSIS) technique, 50 wt.% CR fiber-reinforced MWCNT-phenolic composite was chosen as the optimal composite for mechanical and flammability properties. This bio-based eco-friendly composite has the potential to be used as an aircraft interior component.

Effects of processing parameters on the performance of carbon fiber reinforced polyphenylene sulfide laminates manufactured by laser-assisted automated fiber placement

In situ consolidation of thermoplastic composites can be realized through laser-assisted automated fiber placement (AFP) technology, and the properties of composites were significant affected by the process parameters. In this work, the effects of process parameters on the properties of continuous carbon fiber–reinforced polyphenylene sulfide (CF/PPS) composites manufactured by laser-assisted AFP were investigated. Four-plies CF/PPS prepreg was laid under the combination of different process parameters and the morphology, void content, crystallinity, and inter-laminar shear strength (ILSS) of the composites were characterized. It turned out that the resin distribution on the surface of the composites could be significantly improved by increasing the laser temperature and compaction pressure. The highest crystallinity of the composites reached 46% at tool temperature of 120°C while the value was only 18% when the tool temperature was 40°C. Meanwhile, with the increasing compaction force ranging of 500–2000 N, the void content of the composites decreased obviously. The ILSS was evaluated through double notch tensile shear test. The results indicated that the mechanical properties of the composites were dominated by void content rather than crystallinity.