Extensive reuse of soda-lime waste glass in fly ash-based geopolymers

The possibility of extensive incorporation of soda-lime waste glass in the synthesis of fly ash-based geopolymers was investigated. Using waste glass as silica supplier avoids the use of water glass solution as chemical activator. The influence of the addition of waste glass on the microstructure and strength of fly ash-based geopolymers was studied through microstructural and mechanical characterization. Leaching analyses were also carried out. The samples were developed changing the SiO2/Al2O3 molar ratio and the molarity of the sodium hydroxide solution used as alkaline activator. The results suggest that increasing the amount of waste glass as well as increasing the molarity of the solution lead to the formation of zeolite crystalline phases and an improvement of the mechanical strength. Leaching results confirmed that the new geopolymers have the capability to immobilize heavy metal ions

Mullite Ceramics: Its Properties Structure and Synthesis

Besides its importance for conventional ceramics, mullite has become a choice of material for advanced structural and functional ceramics due to its favourable properties. Some outstanding properties of mullite are low thermal expansion, low thermal conductivity, excellent creep resistance, high-temperature strength, and good chemical stability. The mechanism of mullite formation depends upon the method of combining the alumina- and silica-containing reactants. It is also related to the temperature at which the reaction leads to the formation of mullite (mullitisation temperature). Mullitisation temperatures have been reported to differ by up to several hundred degrees Celsius depending on the synthesis method used. The three synthesis methods used to prepare mullite are discussed in this paper together with an overview of mullite, its properties and the current application of mullite

Synthesis and Characterization of Novel Epoxy Geopolymer Hybrid Composites

The preparation and the characterization of novel geopolymer-based hybrid composites are reported. These materials have been prepared through an innovative synthetic approach, based on a co-reticulation in mild conditions of commercial epoxy based organic resins and a metakaolin-based geopolymer inorganic matrix. This synthetic strategy allows the obtainment of a homogeneous dispersion of the organic particles in the inorganic matrix, up to 25% in weight of the resin. The materials obtained present significantly enhanced compressive strengths and toughness with respect to the neat geopolymer, suggesting their wide utilization for structural applications. A preliminary characterization of the porous materials obtained by removing the organic phase from the hybrid composites by means of heat treatments is also reported. Possible applications of these materials in the field of water purification, filtration, or as lightweight insulating materials are envisage

Guide to the nature and methods of analysis of the clay fraction of tephras from the South Auckland region, New Zealand.

The manual outlines some of the more common laboratory procedures available for qualitatively and quantitatively analysing the composition of the tephric clays, many of which are difficult to determine because of their short range order or 'amorphous' nature. Techniques described and assessed in terms of their rapidity and quantitativeness include XRD, IR, DTA, TEM and SEM, sodium fluoride reactivity, chemical dissolution analyses, and surface area measurements. No one technique alone produces a definitive clay fraction analysis of tephric deposits. -from Author

Development of Maize Stalk Cellulose Fiber Reinforced Calcined Kaolinite Clay Geopolymer Composite

In recent years the popularity of ecological and renewable materials has grown. Aware of the availability of local resources and economic grounds, the attention is paid to the development geopolymer composite. Geopolymers are inorganic polymers that are formed by the polymerization reaction of silico-aluminate and silico-oxide. The aim of the research was to develop single maize stalk cellulose fiber reinforced calcined kaolinte caly based geopolymer composite. Kaolinite clay was characterized for its chemical composition from two different sites located in Ethiopia to use as precursor material. In addition to that, single maize stalk fiber was extracted from the maize stalk local variety by using a retting process, sodium hydroxide purity 98 % used for chemical treatment of the fiber for 30 minutes and its tensile strength 1184 Mpa and young modulus 16 Gpa were determined based on AST M D3822 to use as reinforcement. Sodium hydroxide and sodium silicate in appropriate ratio were used as an alkaline activator. Therefore,  the geopolymer composite developed from chemical treated short single maize stalk cellulose fiber and calcined kaolinite clay based geopolymer matrix activated by sodium water glass.  Geopolymer composites reinforced with 0 weight%, 0.1 weight%, 0.2 weight%, 0.6 weight%, and 1 weight% maize stalk single cellulose were prepared and tested for compression strength according to AST M C 1424. Measured compression strength ranged from 16 Mpa up to 27 Mpa. The result shows that the appropriate addition of single maize stalk cellulose  fibers can improve the Compression strength of a calcined kaolinite based geopolyme

Environmentally Friendly Pervious Concrete for Treating Deicer-Laden Stormwater: Phase II

In Phase I of this project, graphene oxide (GO)-modified pervious concrete was developed using coal fly ash as the sole binder. The primary objectives of Phase II of this project were (1) to evaluate the stormwater infiltration capacity of GO-modified fly ash pervious concrete; (2) to evaluate the durability performance of GO-modified fly ash pervious concrete using freeze/thaw and salt resistance testing methods; and (3) to use advanced analytical tools to fully characterize the GO-modified fly ash binder. Test results indicate different degrees of reduction in concentrations of possible pollutants in stormwater—copper, zinc, sulphate, chloride, ammonia, nitrate, and total phosphate. The incorporation of GO significantly improved the resistance of pervious concrete to freeze/thaw cycles and ambient-temperature salt attack. The specimens were examined using X-ray diffraction, which revealed that the mineralogy and the chemical composition of fly ash pastes differ considerably from those of cement pastes. Nuclear magnetic resonance was used to study the chemical structure and ordering of different hydrates, and provided enhanced understanding of the freeze/thaw and salt scaling resistance of fly ash pervious concrete and the role of GO

Sintering characteristics of red mud compact

Scientific inventions & technological developments has raised the human life to a great height. In last few decades worldwide scientific & technical innovations for processing/development/utilization of new materials (as per the need of the society), is tremendously increasing. But, looking at the other side of the coin also implies the generation of a huge amount of industrial byproducts/wastes which is becoming a client for increasing environmental pollution & generation of a huge amount of unutilized resources. With a view to the above, this research is aimed at finding out utilization of such things/materials/industrial byproducts for value added applications & also helps to solve the environmental problems. The present piece of my research work aims at, to provide a valued input/utilization to industrial byproduct/waste (viz..red mud), being produced in huge quantity from Alumina plants, not bearing any commercial values. From the available research literatures/resources, it’s clearly understood that very little attempts have been made for finding high valued utilization of this material. Considering all these above our investigation are to process red mud for high valued applications. By now search/studies are going on for finding new ways & means available in literature regarding utilization of this material

New low cost and green composite binder for construction

One of the most promising ways to make cement and concrete more sustainable is to blend them with the proper supplementary cementitious materials (SCM). This study evaluates several schist type materials as partial replacement for ordinary Portland cement (OPC). Materials received from several mines in ground powder form were studied by X-ray diffraction, thermogravimetry (TGA), and scanning electron microscopy (SEM). According to the TGA results, the activation procedures for the candidate SCMs were determined. This dissertation includes two main phases. For the first step that is named as calcined clay cement (C3), the virgin powders were heat treated in three different decomposition regimes (30%,50% and 80% of the total weight losses during thermal decomposition). These regimes correspond to the activation level of the potential SCMs due to the de-hydroxylation of the clayey minerals within them. Pozzolanic reactivity (pozzolanicity) of untreated as well as treated powders were estimated via electrical conductivity measurements in calcium hydroxide solution. Blended cement pastes with 30 wt% of OPC substitution with calcined overburden clayey materials have developed mechanical properties equal to pure cement (100wt% OPC) paste after 28 days of setting time. Two blended cement pastes prepared with candidate SCMs were compared to 100% OPC (C) and OPC composite paste with Meta-Kaolinite (MK) which is regarded as literature standard. For the second phase of project is named as limestone calcined clay and carbonate cement (LC4), the same scenario by considering the best activation temperature is carried out. The results represent the possibility of reactivation of any kind of clay class for the ordinary Portland cement partial substitution and obtaining the compressive strength as well as OP

Management and valorisation of wastes through use in producing alkali-activated cement materials

There is a growing global interest in maximising the re-use and recycling of waste, to minimise the environmental impacts associated with waste treatment and disposal. Use of high-volume wastes in the production of blended or novel cements (including alkali-activated cements) is well known as a key pathway by which these wastes can be re-used. This paper presents a critical overview of the urban, agricultural, mining and industrial wastes that have been identified as potential precursors for the production of alkali-activated cement materials, or that can be effectively stabilised/solidified via alkali activation, to assure their safe disposal. The central aim of this review is to elucidate the potential advantages and pitfalls associated with the application of alkali-activation technology to a wide variety of wastes that have been claimed to be suitable for the production of construction materials. A brief overview of the generation and characteristics of each waste is reported, accompanied by identification of opportunities for the use of alkali-activation technology for their valorisation and/or management