Resistance to acid attack, abrasion and leaching behavior of alkali-activated mine waste binders

This paper report results of a research project on the development of alkali-activated binders using mine wastes. Abrasion and acid resistance of two ordinary Portland cement (OPC) strength class concrete mixtures (C20/25 and C30/37) and several mine waste (MW) mixtures were compared. This study indicates that MW binders possess higher acid and abrasion resistance than OPC based concrete mixtures.The leaching assessment of the MW binders shows it can be considered an inert material which indicates that it could be used as a building material

Plant Community Diversity Influences Allocation to Direct Chemical Defence in Plantago lanceolata

Background: Forecasting the consequences of accelerating rates of changes in biodiversity for ecosystem functioning requires a mechanistic understanding of the relationships between the structure of biological communities and variation in plant functional characteristics. So far, experimental data of how plant species diversity influences the investment of individual plants in direct chemical defences against herbivores and pathogens is lacking. Methodology/Principal Findings: We used Plantago lanceolata as a model species in experimental grasslands differing in species richness and composition (Jena Experiment) to investigate foliar concentrations of the iridoid glycosides (IG), catalpol and its biosynthetic precursor aucubin. Total IG and aucubin concentrations decreased, while catalpol concentrations increased with increasing plant diversity in terms of species or functional group richness. Negative plant diversity effects on total IG and aucubin concentrations correlated with increasing specific leaf area of P. lanceolata, suggesting that greater allocation to light acquisition reduced the investment into these carbon-based defence components. In contrast, increasing leaf nitrogen concentrations best explained increasing concentrations of the biosynthetically more advanced IG, catalpol. Observed levels of leaf damage explained a significant proportion of variation in total IG and aucubin concentrations, but did not account for variance in catalpol concentrations. Conclusions/Significance: Our results clearly show that plants growing in communities of varying species richness an

Application of wood waste ash in concrete making: revisited

Portland cement production is a carbon dioxide trigger responsible for almost 5% of the worlds CO2 emissions. Pozzolanic inclusions could contribute to sustainability particularly if they are derived from waste. Managing solid waste is increasingly becoming a global challenge as a result of increasing volume of accumulated waste from industrial and agricultural by-products. Environmental concerns as well as economic implications related with disposal of these wastes have prompted many researches in order to provide viable solutions. Recycling of these waste materials into the construction industry seems to be a more promising and viable alternative most especially in the manufacturing of greener and sustainable concrete material. Wood ash (WA) is a by-product derived from incineration of wood as well as its products such as sawdust, wood bark and chips. This paper presents an overview on investigations performed on the applicability of this material in mortar and concrete making. Specifics on physical, chemical, mineralogical and elemental characteristics of the waste material are discussed. It highpoints the impact of wood ash on workability, compressive and flexure strengths, water absorption, drying shrinkage, carbonation, alkali–silica reaction (ASR) and chloride permeability of concrete