This study aimed to investigate the heavy metals, i.e. Cu, Pb, Ni, and Zn removal efficiency from stormwater runoff of a porous concrete pavement (PCP). A model of PCP was designed with the porosity and co-efficient of permeability of the pavement were 27.2% and 1.83 cm/sec, respectively. Artificial stormwater containing heavy metals are passed through the pavement at a constant rainfall rate to mimic the stormwater rainfall-runoff condition. The artificial stormwater infiltrated through the pavement were then collected at two different pavement layers at different time instances. From the experimental investigations, it is observed that Cu, Pb, Ni and Zn concentrations are significantly reduced in the treated stormwater. At the first collection point which is located below the sub-base layer and coarse sand layer of the pavement, the concentrations of Cu, Pb and Zn reduced 56%, 67% and 93% respectively compared to their initial concentration, Ni concentration reduced only 20%. At the second collection point which is located below the coarse and fine sand layers beneath the pavement, the concentrations of Cu, Pb, Zn, and Ni are reduced 92%, 89%, 100%, 100%, respectively.
Mineral fillers provide a significant role in the Marshall properties of hot mix asphalt for paving applications. The article's goal is to assess the suitability and effectiveness of two minerals (coal dust and wood powder ash) used as fillers in asphalt concrete. Chemical composition test using X-ray fluorescence indicated a high content of SiO2, Fe2O3, and Al2O3, which encouraged us to select the coal dust and wood powder ash as mineral fillers for further investigation. A total of 90 cylindrical Marshall Specimens, made with different percentages (i.e., 4%-8%) of coal dust, wood powder ash, and conventional stone dust filler were prepared to assess the performance of individual filler within the asphalt concrete mix. And after that, volumetric characteristics such as density, stability-flow test, air void, and voids in mineral aggregates have been analyzed to evaluate the effectiveness of every sample and, afterward, to find out the optimum asphalt content. Finally, the optimum asphalt content for every filler material was ascertained, and subsequently, Marshall properties were checked again to assess the optimum filler content in the mix that satisfy all the standard criteria. The overall Marshall properties for both fillers were within the acceptable limits. Though the optimum asphalt content was higher for coal dust than wood powder ash and stone dust, the wood powder ash showed better durability than coal dust. All mixtures have been found to have better resistance to deformation, fatigue, and moisture-induced damages; however, 4% coal dust and 6% wood powder ash satisfied most of the Marshall criteria than other percentages.
Bangladesh is one of the climate risk-prone countries in South Asia facing tremendous challenges to combat sea-level rise and its associated coastal morphological changes. This study aimed to determine the interaction of the sea-level rise and morphological changes, particularly at Cox’s Bazar and Kutubdia Island along the eastern coast of Bangladesh. Available hourly tide gauge data, daily temperature, daily rainfall data, and 15 LANDSAT satellite images for the period of 1983–2016 were analyzed to examine the sea level shore morphological change and associated climate change phenomenon. First, we identified the historical nonlinear sea-level trend using Hilbert-Huang Transformation (HHT) based on the complete ensemble empirical mode decomposition (CEEMD) technique. We divided the study period into three distinct sea-level change periods of 1983–1993, 1993–2003, and 2003–2014 based on nonlinear sea-level trend analysis. The study revealed that the sea level on the east coast of Bangladesh had a moderate rising trend during 1983–1993, slight decrease during 1993–2003, and steep rising trend during 2003–2014. We also observed that a sea-level change within a particular period impacted the shore morphological change after approximately two years, such that the average sea-level change during the period of 1993–2003 might have affected the shore morphology for 1996–2005. Alarming shore erosion was found for the period of 2005–2016 compared to the previous periods of 1989–1996 and 1996–2005 for both Cox’s Bazar and Kutubdia Island. The shore morphology of some segments was also substantially affected due to the geometric shape of the land, significant waves, and shore protection works. This study encourages policymakers to minimize the threats of sea-level rise and ensure sustainable coastal management strategies are introduced to sustain the vital eastern coast of Bangladesh.
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