Promoting the use of crumb rubber concrete in developing countries

The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes.     

Total and Extractable Trace Elements in Lebanese River Sediments: Dry Season Data

Years of political instability have left Lebanon with significant gaps in environmental knowledge. This paper reports new results for trace metals in bed sediments of the river Nahr-lbrahim. The drainage basin of the river Nahr-lbrahim is largely floored by karstified limestone. Metal pollution is operative within the catchment. The objectives of this study were first to identify possible sources of metals (geological and/or anthropogenic) and then to characterise the chemical partitioning of the metals in the sediments. Bed load sediments were sampled at five locations along a 13km stretch from the river mouth, during the dry season. Samples were collected on two dates, dried and then sieved into three mechanical fractions. We report total Fe, Cu, Pb and Zn contents of the <75m sediment fraction for the dry season and interpret the results in terms of geology and point and non-point discharges to the river. Total metal contents were derived from summing the concentrations of metals in the chemical fractions of the sediments. A sequential chemical extraction procedure was applied to the <75m fraction and the data showed that, except for Fe, the carbonate fraction had the largest role in metal sediment deposition.     

Interpreting soil CO<Subscript>2</Subscript> transport and production in oasis cotton field,central Asia

In order to explore soil profile CO₂ transport and production, values of vertical soil profile CO₂ concentration, moisture and temperature were measured continuously during whole cotton growing season in oasis cotton field of Aksu National Experimental Station of Oasis Farmland Ecosystem, central Asia. Simultaneously, soil CO₂ efflux was measured by chamber system to assess the deducing result by Fick’s first law. In our experiment, soil CO₂ effluxes were determined by two related intimately methods. Soil CO₂ releasing at 0–20 cm depth was calculated by gas transport equation and was found to be closely related to soil CO₂ efflux. However, mean values of soil CO₂ production at 0–20 cm depth were less than those of soil CO₂ efflux during the whole cotton growing season. Moreover, there were some negative values of CO₂ production at 0–20 cm depth found during the experimental period.     

Seawalls as a response to coastal erosion and flooding: a case study from Grande Comore,Comoros (West Indian Ocean)

Regional Environmental Change - Many coasts are eroding. In the Comoros, as in many other small island developing states (SIDS), communities frequently respond to coastal erosion by building...     

Does agriculture-induced environmental Kuznets curve exist in developing countries?

Even though the economic growth and the increased agricultural production bring welfare increment, they could also load significant environmental costs to society. This study aims to investigate the existence of agriculture-induced EKC hypothesis in 47 developing countries during 1976–2017 by using dynamic panel data estimators. According to the long-run findings of the DOLS and the FMOLS estimators, there is an inverted U-shaped relationship that exists between income and the CO₂ emissions, while agricultural production has a negative impact on environmental quality. In addition, the PMG estimator is also employed for robustness check. Likewise the DOLS and the FMOLS findings, the long-run results of the PMG estimator also support the existence of agriculture-induced EKC for developing countries. The empirical findings of this study provide stimulus results of policy makers to re-consider their current production infrastructure of agricultural sector to achieve sustainable development.

     

The diagnostic accuracy of intraoperative frozen section biopsy for diagnosis of sentinel lymph node metastasis in breast cancer patients: a meta-analysis

Environmental Science and Pollution Research - Sentinel lymph node (SLN) sampling is important for evaluating the nodal stage of breast cancer when the axillary nodes are clinically free of...     

UVA-irradiated dual photoanodes and dual cathodes photocatalytic fuel cell: mechanisms and Reactive Red 120 degradation pathways

Environmental Science and Pollution Research - To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and...     

Protective effects of thymoquinone and diallyl sulphide against malathion-induced toxicity in rats

Environmental Science and Pollution Research - Malathion is a potent organophosphate insecticide that inhibits acetylcholinesterase (AChE) enzyme. Our experimental objective was to investigate the...     

Cost analysis of alternative methods for wastewater handling in small communities

Wastewater collection and treatment is quite important for sustainable management. It would be uneconomical and impractical to provide sewer systems and separate wastewater treatment plants (WWTP) for small communities. The decision process in wastewater planning is rather important in terms of comparing the alternatives considered. The two important points in the management of wastewater at rural areas not connected to a sewer system are to develop an optimized operation strategy and to make sure that the complete system is environmentally and economically sustainable. In some regions, package treatment could be an alternative solution. However, in cases where there is an existing large WWTP, a cluster system, where sewage generated by small communities could be transported via conveyors to a centralized WWTP, could be employed. In this study, the wastewater treatment and disposal problems in small communities were addressed and an alternative wastewater handling scenario was proposed. Additionally, three wastewater handling scenarios were compared. As a case study, Gebze villages were selected.     

Genotype × environment interactions: survival performance of six internationally sourced provenances of <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss in a degraded land in Kano,Nigeria

In order to prevent ‘an impending neem failure’, from the incidence of the twin problems of the neem scale insect infestations and neem dieback, six authenticated provenances (Allahabad, Karnataka, Jodphur, Madinipur, Mukkambu and Annur), from the natural range of the species in India, were collected and appraised for survival in a degraded land in Kano, Nigeria. Established in a completely randomised block design with four replications, the trial was conducted with a view to restrengthening and/or replacing the already weakened Local Land Race of the species in the study area. There was a statistically significant difference in the survival of the seven provenances. The established differences are between Allahabad 83% (6.40 SEM), Mukkambu 83% (6.40 SEM), Annur 76% (4.90 SEM), Jodphur 63% (15.09 SEM) and Madinipur 56% (6.73 SEM), on the one hand, and Karnataka 17% (1.91SEM) and the Local Land Race, with 13% (0.13 SEM), on the other hand. The research recommends Allahabad and Mukkambu 83% (6.40 SEM) based on this outstanding performance.