The construction industry in Senegal is experiencing an upsurge in the development of residential housing units and administrative buildings within the new Diamniadio municipality, an area located just about 35 km fro...The construction industry in Senegal is experiencing an upsurge in the development of residential housing units and administrative buildings within the new Diamniadio municipality, an area located just about 35 km from the capital city of Dakar. Laboratory oedometer or expansive-index tests, however, show poor density and compromised shear strength in the soil samples within the area -posing serious construction problems due to significant volume changes (swellings) that occur when subjected to moisture, thus, bringing into question the structural performance integrity of the soil, and the financial implications of substitute soil types used to compensate for its poor tensile strength. By way, the companies collect the soil of this location (Diamniadio) and throw it to make pile or micro-pile (pious) for their structures. This article demonstrates how we can value the soil of Diamniadio and the Typha Australis in residential building with a reasonable cost. Typha Australis is a plant generally luxuriant within the northern and central belts of Senegal but also known for its negative ecological impacts on the agricultural production of rice. The valorisation of the soil of Diamniadio will pass by the ability to increase its stability or to decrease its shrinkage/swelling rate. When we achieve it, the soil associate with Typha Australis will be used for small bricks which can be useful for partition wall and so the soil will not be ever thrown as a non-useful material. Tests results of soil specimens extracted from the site show a shrinkage rate of 29.19% with estimated cracking depths of 3.5 cm. But by adding gradually Typha Australis, the shrinkage rate will pass from 29.19% to 5.13% with the material treats with 10% by mass of Typha Australis. Moreover, the crackings in the cylindrical specimen disappear. That shows the increase of the stability;thus the composition will be used for building bricks. However, the densities will also be affected by the presence of Typha Australis. The density is decreased from 2032.28 Kg/m<sup>3</sup> for the soil without Typha Australis to 937 Kg/m<sup>3</sup> for the one with 10% of Typha Australis.展开更多
Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha lat...Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season（May–September）in 2011 at two sites with the high and low metal loads,respectively.The objective of this study was to understand the metal（Fe,Mn,Cu,Pb and Zn）concentration and spatial distributions in P.australis and T.latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence（μXRF）and synchrotron X-ray computed microtomography（μCMT）techniques.The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis.Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different.Significant correlations were found between metals（Cu,Mn,Pb and Zn）and Fe in the epidermis,implying that metals were scavenged by Fe oxides.The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific.The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation.展开更多
Energy consumption in the building sector is constantly increasing and represents more than 44% in the residential and tertiary sectors in many <span><span style="font-family:Verdana;">countries&...Energy consumption in the building sector is constantly increasing and represents more than 44% in the residential and tertiary sectors in many <span><span style="font-family:Verdana;">countries</span><span style="color:#C45911;"> </span></span><span style="font-family:Verdana;">[1]</span><span></span><span><span></span></span><span style="font-family:Verdana;">. Thus, the building represents a real possibility of energy saving and is the subject of several studies particularly in actual context of experimentation</span><span style="font-family:Verdana;"> with materials based on plant fibers (hemp, flax, millet wastage, etc.). These biobased materials such as typha have shown real interest in the buildings construction due to their light and porous nature. It’s in this context that we were interested in typha australis mixed with classic aggregates (cement, sand, gravel 3/8) to make typha’s concrete. On this concrete, we carried out experimental measurements in order to better understand its contributions in the building. The interesting results obtained show that typha australis, which is an invasive and harmful grass, can be valued and integrated among local building materials in the form of typha’s concrete in order to improve the energy efficiency of buildings.</span>展开更多
This study examines the use of sand from the Chari River in N’Djamena as a partial addition to Portland cement,aiming to improve the characteristics of Typha australis-based concrete.Concrete samples with Typha austr...This study examines the use of sand from the Chari River in N’Djamena as a partial addition to Portland cement,aiming to improve the characteristics of Typha australis-based concrete.Concrete samples with Typha australis fibers were tested,revealing that fine sand contributes through physico-mechanical effects.The use of Typha australis aims to reduce construction costs and energy consumption.Three cement contents(6%,8%,and 10%)and six Typha fiber contents(0.5%,1%,1.5%,2%,2.5%,and 3%)were tested,with curing times of 7,14,and 28 days.Typha is used for insulation and non-load-bearing building blocks,providing good thermal insulation.Increasing cement content improves compressive strength,while low content causes sintering.The results show an improvement in compressive strength at 10%cement,of 1.98 MPa on the 7th day and of 2.75 MPa on the 14th day,with the addition of 0.5%Typha.The compressive stresses are 4.21 MPa and 2.03 MPa for Typha contents ranging from 0.5%to 1%on the 28th day.展开更多
文摘The construction industry in Senegal is experiencing an upsurge in the development of residential housing units and administrative buildings within the new Diamniadio municipality, an area located just about 35 km from the capital city of Dakar. Laboratory oedometer or expansive-index tests, however, show poor density and compromised shear strength in the soil samples within the area -posing serious construction problems due to significant volume changes (swellings) that occur when subjected to moisture, thus, bringing into question the structural performance integrity of the soil, and the financial implications of substitute soil types used to compensate for its poor tensile strength. By way, the companies collect the soil of this location (Diamniadio) and throw it to make pile or micro-pile (pious) for their structures. This article demonstrates how we can value the soil of Diamniadio and the Typha Australis in residential building with a reasonable cost. Typha Australis is a plant generally luxuriant within the northern and central belts of Senegal but also known for its negative ecological impacts on the agricultural production of rice. The valorisation of the soil of Diamniadio will pass by the ability to increase its stability or to decrease its shrinkage/swelling rate. When we achieve it, the soil associate with Typha Australis will be used for small bricks which can be useful for partition wall and so the soil will not be ever thrown as a non-useful material. Tests results of soil specimens extracted from the site show a shrinkage rate of 29.19% with estimated cracking depths of 3.5 cm. But by adding gradually Typha Australis, the shrinkage rate will pass from 29.19% to 5.13% with the material treats with 10% by mass of Typha Australis. Moreover, the crackings in the cylindrical specimen disappear. That shows the increase of the stability;thus the composition will be used for building bricks. However, the densities will also be affected by the presence of Typha Australis. The density is decreased from 2032.28 Kg/m<sup>3</sup> for the soil without Typha Australis to 937 Kg/m<sup>3</sup> for the one with 10% of Typha Australis.
基金supported in part by the Margaret and Herman Sokol Foundation(HF)China Scholarship Council(YQ)+6 种基金the State Key Laboratory of Estuarine and Coastal Research Open Research Fund(Ref #:SKLEC-KF201304)(HF,WZ,LY,YQ)supported in part by the U.S.Department of Energy,Office of Science,Office of Workforce Development for Teachers and Scientists(WDTS)under the Visiting Faculty Program(VFP)(HF)Portions of this work were performed at Beamline X27A,National Synchrotron Light Source(NSLS),and Biosciences Department,Brookhaven National LaboratoryWork in Bioscience Department,BNL,was partially supported by the Division of Chemical Sciences,Geosciences,and Biosciences,Office of Basic Energy Sciences of the US Department of Energy through Grant DEAC0298CH10886the National Science Foundation through grant MCB-1051675(CJL)X27A is supported in part by the U.S.Department of Energy--Geosciences(DE-FG02-92ER14244 to The University of Chicago-CARS)Use of the NSLS was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-98CH10886
文摘Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season（May–September）in 2011 at two sites with the high and low metal loads,respectively.The objective of this study was to understand the metal（Fe,Mn,Cu,Pb and Zn）concentration and spatial distributions in P.australis and T.latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence（μXRF）and synchrotron X-ray computed microtomography（μCMT）techniques.The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis.Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different.Significant correlations were found between metals（Cu,Mn,Pb and Zn）and Fe in the epidermis,implying that metals were scavenged by Fe oxides.The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific.The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation.
文摘Energy consumption in the building sector is constantly increasing and represents more than 44% in the residential and tertiary sectors in many <span><span style="font-family:Verdana;">countries</span><span style="color:#C45911;"> </span></span><span style="font-family:Verdana;">[1]</span><span></span><span><span></span></span><span style="font-family:Verdana;">. Thus, the building represents a real possibility of energy saving and is the subject of several studies particularly in actual context of experimentation</span><span style="font-family:Verdana;"> with materials based on plant fibers (hemp, flax, millet wastage, etc.). These biobased materials such as typha have shown real interest in the buildings construction due to their light and porous nature. It’s in this context that we were interested in typha australis mixed with classic aggregates (cement, sand, gravel 3/8) to make typha’s concrete. On this concrete, we carried out experimental measurements in order to better understand its contributions in the building. The interesting results obtained show that typha australis, which is an invasive and harmful grass, can be valued and integrated among local building materials in the form of typha’s concrete in order to improve the energy efficiency of buildings.</span>
文摘This study examines the use of sand from the Chari River in N’Djamena as a partial addition to Portland cement,aiming to improve the characteristics of Typha australis-based concrete.Concrete samples with Typha australis fibers were tested,revealing that fine sand contributes through physico-mechanical effects.The use of Typha australis aims to reduce construction costs and energy consumption.Three cement contents(6%,8%,and 10%)and six Typha fiber contents(0.5%,1%,1.5%,2%,2.5%,and 3%)were tested,with curing times of 7,14,and 28 days.Typha is used for insulation and non-load-bearing building blocks,providing good thermal insulation.Increasing cement content improves compressive strength,while low content causes sintering.The results show an improvement in compressive strength at 10%cement,of 1.98 MPa on the 7th day and of 2.75 MPa on the 14th day,with the addition of 0.5%Typha.The compressive stresses are 4.21 MPa and 2.03 MPa for Typha contents ranging from 0.5%to 1%on the 28th day.
