Fatigue Behavior of a Pavement Foundation with Recycled Aggregate and Waste HDPE Strips

A laboratory investigation was conducted to evaluate the fatigue behavior of an alternative pavement foundation material containing cement stabilized reclaimed crushed aggregate. Class C fly ash, and waste-plastic strip [high density polyethylene (HDPE)] reinforcement. The primary motivation for this research was to evaluate a composite that contained more than 90% recycled materials for use as an alternative foundation layer underneath conventional flexible or rigid pavement. The specific objectives of this study were (1) to evaluate the flexural fatigue behavior of the new composite, and (2) to evaluate the accumulation of fatigue damage in the material. The results indicate that the fatigue resistance of this material is similar to other traditional stabilized pavement materials. It was found that the dynamic elastic modulus remained approximately constant (degraded slowly) for most specimens up to the end of fatigue life. Fatigue damage computed using a dissipated energy approach showed that the damage accumulation in this material approximately follows Miner's rule for cumulative damage, which is often used in pavement engineering.     

Using Weibull Analysis for Evaluation of Cost and Schedule Performance

Large amounts of money are lost each year in the construction industry because of poor schedule and cost control. Few contractors specify and follow systematic schedule monitoring practices. Traditionally, the earned value method (EVM) is used to control and monitor schedule performance using the schedule and cost performance indices which compare the budgeted cost of work performed to what was originally scheduled or what is actually expended. This paper presents a statistical approach, namely Weibull analysis, to evaluate stochastically the schedule performance of construction or design projects. The approach can be used in conjunction with the EVM to enhance the evaluation and control of schedule performance. Weibull analysis is a common method for failure analysis and reliability engineering used in a wide range of applications. In this paper, the applicability of Weibull analysis for evaluating and comparing the reliability of the schedule performance of multiple projects is presented. The various steps in the analysis are discussed along with an example in which two projects are analyzed and compared. The authors conclude that Weibull analysis has several advantages and provides a relatively robust and effective method for construction managers to better control and monitor their projects.     

Out-of-Plane Flexural Performance of GFRP-Reinforced Masonry Walls

The objective of this paper is to assess the out-of-plane flexural performance of masonry walls that are reinforced with glass fiber-reinforced polymers (GFRPs) rods, as an alternative for steel rebars. Eight 1?m×3?m full-scale walls were constructed using hollow concrete masonry units and tested in four-point bending with an effective span of 2.4 m between the supports. The walls were tested when subjected to increasing monotonic loads up to failure. The applied loads would represent out-of-plane loads arising from wind, soil pressure, or inertia force during earthquakes. One wall is unreinforced; another wall is reinforced with customary steel rebars; and the other six walls are reinforced with different amounts of GFRP reinforcement. Two of the GFRP-reinforced walls were grouted only in the cells where the rods were placed to investigate the effect of grouting the empty cells. The force-deformation relationship of the walls and the associated strains in the reinforcement were monitored throughout the tests. The relative performance of different walls is assessed to quantify the effect of different design variables. The range of GFRP reinforcement ratios covered in the experiments was used to propose a capacity diagram for the design of FRP-reinforced masonry walls similar to that of reinforced concrete elements.     

Low-Temperature Preparation and Magnetic Properties of V-Doped SnO2 Nanoparticles

A solid solution of vanadium (V)-doped tin oxide (SnO₂) particles of average diameter 2 nm and V content of 19 at.% was prepared at normal pressure and low temperature (100°C) by mixing wet SnO₂ gel SnO₂· x H₂O with a boiling solution of vanadium oxide (V₂O₅). Experimental characterizations using X-ray, electron diffraction, and transmission electron microscope show evidence of a pure single phase. The nanoparticles exhibit a mixed magnetic behavior, namely paramagnetic and ferromagnetic. Their thermal stability is also investigated. At higher temperature, 850°C, some amount of Fe precipitates from the solid solution.     

An investigation of pore cracking in titanium welds

Two welded Ti-6A1-4V pressure vessels leaked prematurely in service. The leaks were caused by cracks emanating from weld porosity. The cracks originated during fabrication, with subsequent growth in service leading to the formation of the leak paths. Pore cracking is thought to be caused by a mechanism that involves both sustained-load and cyclic contributions, with the former being the more prominent. It is shown that the tendency for cracking is influenced by pore position and that pore size is not a deciding factor in that regard. The factors that govern pore cracking are discussed, and the possible role of interstitial embrittlement is assessed.     

Adsorptive removal of nitrate and phosphate anions from aqueous solutions using functionalised SBA‐15: Effects of the organic functional group

Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering     

Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators

Previously, we reported the identification of a thiazolidinedione‐based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N‐[4‐({3‐[(1‐methylcyclohexyl)methyl]‐2,4‐dioxothiazolidin‐5‐ylidene}methyl)phenyl]‐4‐nitro‐3‐(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial–mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK‐activating activities of individual derivatives revealed a distinct structure–activity relationship and identified 59 (N‐(3‐nitrophenyl)‐N′‐{4‐[(3‐{[3,5‐bis(trifluoromethyl)phenyl]methyl}‐2,4‐dioxothiazolidin‐5‐ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1 , compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT‐associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)‐null PC‐3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN‐negative cancer and warrants continued investigation in this regard.     

Novel composite sandwich structure from green materials: Mechanical,physical, and biological evaluation

Flax and Jute fabrics were used as reinforcements with polyester resin to form composite skins while poplar particleboard was used as a core for making composite sandwich structures by applying vacuum assisted resin transfer molding (VARTM) technique. Mechanical, physical, and biological properties of these novel composite sandwich structures were evaluated. The results showed that the proposed engineered panels have superior mechanical properties that are suitable for different structural applications compared with conventional particleboards. When compared with the control panels, significant enhancement on Modulus of elasticity (MOE) and Modulus of rupture (MOR) were achieved. On the other hand, the results indicated that the proposed panel composites exhibit better dimensional stability compared with poplar particleboard control panels. In addition, the proposed composite sandwich structures proved resistant against the decay fungi after 12 weeks of fungal exposure. Obviously, the developed composite panels could be used in a wide variety of applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42253.     

Evaluation of electrochemical frequency modulation as a new technique for monitoring corrosion and corrosion inhibition of carbon steel in perchloric acid using hydrazine carbodithioic acid derivatives

Electrochemical frequency modulation, EFM is a new technique for corrosion rate measurements. With the EFM technique, the corrosion rate and corrosion kinetic parameters can be obtained instantaneously without prior knowledge of Tafel slopes, which makes this method an ideal technique for application as a corrosion monitoring tool. Results obtained with the EFM technique were shown to be in agreement with chemical (weight loss) and electrochemical methods (Tafel extrapolation and electrochemical impedance spectroscopy, EIS) for corrosion rate measurements. New synthesized hydrazine carbodithioic acid derivatives namely, N′-furan-2-yl-methylene-hydrazine carbodithioic acid (A), N′-(4-dimethylamino-benzylidene)-hydrazine carbodithioic acid (B) and N′-(3-nitro-benzylidene)-hydrazine carbodithioic acid (C) were examined as corrosion inhibitors for carbon steel in 1 M perchloric acid solution. The results obtained from both chemical and electrochemical measurements show that these compounds suppressed both anodic and cathodic processes of carbon steel corrosion in 1 M HClO₄ by adsorption on the electrode surface. The adsorption mode follows the Langmuir adsorption isotherm. The efficiency of the inhibitors increases in the order C > B > A.