Utilization of waste for building materials – a review

In coastal landfill facilities that are constructed to contain municipal and industrial wastes in Japan, natural marine clay layers serve as bottom liners to prevent pollutant migration. Leachates from landfills are rich in dissolved organic carbon (DOC) that can be used by micro-organisms. Biological processes could lead to redox reactions that change the pH and Eh. These biochemical factors may strongly influence the behavior of pollutants leached from landfills, particularly heavy metals. In this paper, modified batch tests were conducted to investigate the effects of pH and Eh and to simulate both chemical and biochemical reactions on zinc mobility in a marine clay layer. To examine the effects of pH and Eh, the pH and Eh were controlled by adding acid or base, respectively, and a reducing agent. To study the zinc mobility, biochemical reactions were enhanced by cultivating native micro-organisms, which gradually changed the pH and Eh conditions. Batch tests with different DOC concentrations were also conducted to evaluate the effect of DOC on zinc mobility. In addition, biochemical processes in the bottom clay liners at coastal landfill sites that receive municipal solid waste (MSW) incinerator ash were simulated by batch tests using a solution of MSW incinerator ash mixed with seawater along with cultivating native micro-organisms found in marine clay. The experimental results indicated that microbial activities in closed soil-water systems result in strongly reduced conditions compared to that controlled by a strong reducing agent, and that the zinc mobility is lowered through the formation of sulfides. Although microbial activity was initially limited under highly alkaline conditions due to MSW incinerator ash, the pH gradually decreased mainly due to the formation of organic acids from microbial activity. Under the oxidized conditions, the solubility of zinc was controlled by pH and the Eh had a negligible effect on the zinc concentration. DOC in the leachate served as a bioavailable carbon source for microbial activities, which promoted anaerobic conditions in the soil-water system and the immobilization of zinc. However, DOC also formed soluble complexes with heavy metals, which increased the zinc concentration. These observations confirmed that heavy metals in the leachates became immobilized under the conditions found at landfill bottom liners when estimated in terms of pH, Eh, and DOC.

The objectives of this research is to investigate the influence of Municipal Solid Waste Incinerated Bottom Ashes (MSWI-BA) on engineering properties of specimens when part of fine aggregate is replaced with it. Disposal of municipal wastes is a major key issue which causes a problematic challenge in Lebanon as landfill space for the disposal of ash from Municipal Solid Waste Incineration (MSWI) becomes rare. It becomes smarter to reduce the volume of materials being disposed. Recycling is one approach, waste minimization is the second, and combustion for energy production is the third. Therefore, one of the possibilities that have a beneficial impact on the environment and consequently on the society is to use Municipal Solid Waste Incineration (MSWI) ashes in concrete production, as it is done with coal combustion products. The bottom ash features the most convenient composition for this purpose as it is available in highest amounts among the MSWI ashes. Bottom ash can be used as partial replacement of sand in concrete. This has the additional advantage of replacing sand and gravel, which must be mined sometimes from environmentally sensitive areas. The properties of concrete with partial substitution of sand by bottom ash up to 50% was investigated in terms of compressive strength, pulse velocity, capillary and total absorption. The bottom ash incorporated in the concrete behaves almost like ordinary sand. These results indicates that the use of waste in concrete constitutes a potential means of adding value and at the same time reduce greenhouse gases.

The replacement of natural resources in the manufacture of cement and sand is the present issue in the present construction scenario. Copper slag and Ground Granulated Blast furnace Slag (GGBS) are industrial by-product materials produced from the process of manufacturing copper and iron. Use of Copper slag and GGBS does not only reduce the cost of construction but also helps to reduce the impact on environment by consuming the material generally considered as waste product. Hence in the current study an attempt has been made to minimize the cost of cement and sand with concrete mix grade M25 by studying the mechanical behavior of this concrete mix by partial replacing with advanced mineral admixtures such as Copper slag and GGBS in concrete mix. In this study, partial replacement of Cement with GGBS and Sand with Copper Slag considered. Experimental study is conducted to evaluate the workability and strength characteristics of hardened concrete, properties of concrete have been assessed by partially replacing cement with GGBS, and sand with Copper Slag. The cement has been replaced by GGBS accordingly in the range of 0% (without GGBS), 5%, 10%, 15%, and 20% by weight of cement for M25 mix. The sand has been replaced by Copper slag accordingly in the range of 0% (without Copper slag), 10%, 20%, 30%, and 40% by weight of cement for M25 mix. Concrete mixtures were produced, tested and compared in terms of compressive, flexural and split tensile strength with the conventional concrete. Keywords - Copper slag, GGBS, Workability, Compressive strength, Split tensile strength, Flexural strength.

Properties of dredged sludge solidified with alkali-activated slag-based materials and blended with copper slag as fine aggregates of mortars

Nowadays very vast quantity of concrete is being used all over the world. Concrete is a mixture of cement, fine aggregate, coarse aggregate, and water. Fly ash, Copper slag, and GGBS are mechanical waste products in Coal, copper and iron industry respectively. Using this product, results in cost reduction of concrete and disposal solution of large waste products. In this review two combinations were taken and attempt was made to reduce usage of cement and sand content by saving cost of concrete and studied experimental behavior for strengths of M40 grade of concrete for combination of ground granulated blast furnace slag (GGBS) and Copper Slag (CS) and another combination of GGBS and Fly ash (FA). Experimental studies were performed on plain cement concrete and combination of GGBS and Copper Slag. Total 108 specimens were casted. In the first combination, four trial mixes were taken as maintaining GGBS 30% and varying Copper Slag by 10%, 20%, 30%, and 40% respectively. In second combination 4 trials were taken as maintaining fly ash 25% and varying GGBS by 40%, 50%, 60%, and 70%. A comparative analysis has been carried out for concrete in relation to Workability, Compression strength, Split Tensile strength and Flexural strength at 7,14,28 days with conventional concrete and two combinations. It was observed that replacement of cement by 30% GGBS and sand by 30% CS in combination 1 got maximum strength in all aspect than Conventional Concrete and combination 2.

The rapidly increasing generation of municipal solid waste (MSW) threatens the environmental integrity and well-being of humans at a global level. Incineration is regarded as a technically sound technology for the management of MSW. However, the effective management of the municipal solid waste incineration (MSWI) ashes remains a challenge. This article presents the global dynamics of MSWI ashes research from 1994 to 2018 based on a bibliometric analysis of 1810 publications (research articles and conference proceedings) extracted from the Web of Science database, followed by a comprehensive summary on the research developments in the field. The results indicate the rapid growth of annual publications on MSWI ashes research, with China observed as the most productive country within the study period. Waste Management, Journal of Hazardous Materials, Chemosphere and Waste Management & Research, which accounted for 35.42% of documents on MSWI research, are the most prominent journals in the field. The most critical thematic areas on this topic are MSWI ashes characterisation, dioxin emissions from fly ash, valorisation of bottom ash and heavy metal removal. The evolution of MSWI ashes treatment technologies is also discussed, together with the challenges and future research directions. This is the first bibliometric analysis on global MSWI ashes research based on a sufficiently large dataset, which could provide new insights for researchers to initiate further research with leading institutions/authors and ultimately advance this research field.

Municipal solid waste incineration (MSWI) ash co-disposal: Influence on per- and polyfluoroalkyl substances (PFAS) concentration in landfill leachate

Utilization of industrial and agricultural waste materials for the development of geopolymer concrete- A review

In recent years, scientists have extensively investigated the use of internal curing methods in concrete to improve its ability to retain water. It has been observed that proper curing forms an important step in enhancing the strength and durability of concrete, which has been found to exert a significant influence on its overall development. A study on the structural properties of self-curing concrete is discussed in the following research article. SCBA and CS are used as supplementary materials along with the concrete mix. PEG-400 is used as the self-curing agent in the concrete mix. This research is based on the discussion of the properties of the new concrete mixture. The study looks into how the components will influence the mechanical behavior of the concrete. For testing purposes, two mixtures of the concrete were prepared. The first lot involved five mix ratios of the concrete, with the control mixture containing 0.5% to 2% PEG-400 relative to cement weight. For the second mix, copper slag (CS) replaced part of the fine aggregate and was at the age of 40%, while the cement was partially substituted with an amount of 5-20% sugarcane bagasse ash (SCBA) in self-curing concrete, which contains 1% PEG-400. Investigations were conducted to prove the possibility of self-curing concrete admixed with CS and SCBA. Slump cone, compressive, split tensile and flexural strengths are explored during these tests.

This paper reports the results of an experimental program performed to study the effect of incorporation of sugarcane bagasse ash (SCBA) in Ground granulated blast furnace slag (GGBS) based geopolymer composites by performing various destructive and non-destructive tests. GGBS was replaced by SCBA in dosages of 5%, 10%, 15% and 20% by weight and activated by a solution of sodium hydroxide and sodium silicate. Some of the test performed during the experimental investigation were compressive strength, water absorption, bulk density, rebound hammer test, ultrasonic pulse velocity etc. It is observed that compressive strength and bulk density decreases with increase in the dosage of SCBA. The results of the present study indicates suitability of replacing SCBA in the GGBS based geopolymer composites.

The number of waste-producing industries has been increasing consistently and, at the same time, natural resources are depleting simultaneously. Reusing the wastes produced in the industry is definitely more beneficial than their disposal. At present, the construction sector is using a lot of natural resources, which could be reduced by proper utilization of industrial wastes. The waste products generated in the industry has been widely accepted in concrete manufacturing. As the demand for cement, which is a major component of concrete, will continue to increase daily, it is essential to use alternative cementations materials in order to reduce carbon emission. Other materials which come as the industrial waste like fly ash, construction and demolition waste, red mud, silica fume, ground granulated blast furnace slag, ferrochrome ash, ferrochrome slag, brick aggregate, marble waste, etc. are to be utilized in the cement concrete industry. All these are industrial waste products and are harmful to the environment. The objective of this study is to utilize and optimize the benefits of using various types of waste for replacement of cement along with identification of substitute materials for use as aggregates in concrete.

Over the years, supplementary cementitious materials (SCM) have been successfully utilized in concrete buildings, but they have been rarely exploited in concrete pavements. In recent years, due to the growing importance of concrete pavements, researchers have begun studying the performance of various types of SCMs from pavement perspective. The overview herein assesses the existing research associated with utilizing different kinds of silica-rich waste as SCM. For this purpose, five agricultural waste (AW) comprising rice husk ash (RHA), rice straw ash (RSA), corn cob ash (CCA), palm oil fuel ash (POFA), sugarcane bagasse ash (SBA) and three industrial by-products (IB), i.e., fly ash (FA), ground granulated blast furnace slag (GGBFS) and microsilica (MS), were selected. Their effects on various properties of concrete were exhaustively reviewed. This study also furnishes reasons for limited literature on SCMs utilization in concrete pavements. Moreover, this review accentuates the previous studies' gaps, which require further research, such as the need for dedicated standard codes for AW utilization in concrete pavements. The guidance for future research to further enhance the properties of pavement quality concrete is also given.

Geotechnical characterization of a Municipal Solid Waste Incineration Ash from a Michigan monofill

Africa is a continent with abundant, diverse and un-exploited renewable energy resources that are yet to be used for improving the livelihood of the vast majority of the population. The production of biogas via anaerobic digestion of large quantities of agricultural residues, municipal wastes and industrial waste(water) would benefit African society by providing a clean fuel in the form of biogas from renewable feedstocks and help end energy poverty. Biogas technology can serve as a means to overcome energy poverty, which poses a constant barrier to economic development in Africa. Anaerobic digestion of the large quantities of municipal, industrial and agricultural solid waste in developing countries present environmental conditions that make use of anaerobic biotechnology extremely favourable under perspective of sustainable development. However, the use of biogas is not widespread in Africa. There are many reasons of economic, technical and non-technical nature for the marginal use of biogas in Africa. The key issue for biogas technology in Africa is to understand why large scale-up has not occurred despite demonstration by several programmes of the viability and effectiveness of biogas plants. This article provides knowledge-based review of biogas technology status, constraints and prospects in Africa. In addition, recommendations to overcome the technological and non-technological challenges to commercialise biogas are discussed. Recommendations for large scale adoption for biogas technology include establishing national institutional framework, increasing research and development, education and training and providing loans and subsidies and major policy shift in the energy sector. The conclusion is that biogas technology must be encouraged, promoted, invested, researched, demonstrated and implemented in Africa.

Mechanical, microstructural and energetic evaluation of conventional and one-part alkali-activated mixtures with raw sugarcane bagasse ash