Geopolymer Synthesis from Demolished Concrete Wastes (original) (raw)
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Comparative Study of the Geopolymers Synthesized from Various Types of Construction Wastes
Nepal Journal of Science and Technology, 2013
Demolition of old houses and construction of new buildings are in peak in urban sectors which generate a huge amount of construction wastes. These wastes are rich source of alumino-silicate. Geopolymerization can transform a wide range of alumino-silicate materials into building materials with excellent physicochemical properties. Thus, geopolymers have been synthesized from construction wastes such as sand-cement-mixture (SCM), concrete mixture (CM), brick dust (BD), etc using alkali and alkali-silicate as activators. Parameters like alkali concentration (for dissolution of alumino-silicate), ratio of alkali-silicate to construction wastes and curing time were varied to improve the quality of geopolymeric products. The maximum compressive strengths of geopolymeric products obtained from BD, SCM and CM were 60.0, 47.0 and 45.5 MPa respectively. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 81-86 DOI: http://dx.doi.org/10.3126/njst.v14i1.8926
Materials and Contact Characterisation IX, 2019
Geopolymers are inorganic amorphous aluminosilicate materials, which can be produced by the alkali activation of materials with high aluminum and silicon content. In this research, we prepared geopolymer samples obtained from construction and demolition (C&D) waste materials (brick powder and concrete powder), as well as industrial waste material (aluminum dross), and we investigated them using different test methods. Density, particle size distribution and chemical elemental composition were determined on the dried powdered waste materials, and microstructural observations were also made using a scanning electron microscope (SEM) technique. To prepare the geopolymer sample mixtures of sodium-hydroxide and sodium silicate, we used an alkali activator solution at different concentrations (4 M, 8 M and 12 M). We used Fourier Transformation Infrared Spectroscopy (FTIR) to reveal new phases in geopolymer samples. Compression strength was determined after 7 days and after 28 days. In the cases when aluminum dross was used, a gas-forming reaction took place in the geopolymer pastes; therefore, foamed geopolymer was produced. According to these results, the used C&D and industrial wastes may be potential raw materials which could be used to prepare geopolymers.
Construction Wastes as Raw Materials for Geopolymer Binders
International Journal of Civil Engineering, 2009
It has been shown that geopolymerization can transform a wide range of waste aluminosilicate materials into building materials with excellent chemical and physical properties such as fire and acid resistance. In this research work, geopolymerization of construction waste materials with different alkali-activators based on combinations of Na 2 SiO 3 and NaOH has been investigated. A number of systems were designed and prepared with water-to-dry binder ratio, silica modulus, and sodium oxide concentration were adjusted at different levels and setting time and 28-day compressive strength were studied. The results obtained reveal that construction wastes can be activated using a proportioned mixture of Na 2 SiO 3 and NaOH resulting in the formation of a geopolymer cement system exhibiting suitable workability and acceptable setting time and compressive strength. Laboratory techniques of Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were utilized for studying molecular and microstructure of the materials.
Geopolymer concrete: Turn waste into environmentally friendly concrete
International Conference on Recent Trends in Concrete Technology and Structures (INCONTEST), 2003
Efforts are needed to develop environmentally friendly construction materials in order to reduce the greenhouse gas emissions. This paper presents the development of geopolymer concrete. In geopolymer concrete, the inorganic alumino-silicate polymer gel synthesised from source materials rich in silicon and aluminium, such as low calcium (class F) fly ash, binds the loose coarse and fine aggregates, and other unreacted materials in the mix. The test results demonstrate the excellent potential of geopolymer concrete to be a material of choice for the future.
Development of Novel Constructional Material from Industrial Solid Waste as Geopolymer
IOP Conference Series: Materials Science and Engineering, 2018
In present investigations, Geopolymer is made from thermal power plant waste obtained such as Pond Ash. The mechanism involved is that the silicon and aluminium present in the waste reacts with alkali liquid, forming Geopolymer which binds other non-reactive materials in the waste. The highest strength level achieved for as-prepared Geopolymers 19 MPa by curing 1 day. The strength level of Geopolymeric products are 22 MPa (Geopolymeric Motar) and 31 MPa (Geopolymer concrete), respectively. SEM micrographs reveal that there is a gradual transformation from irregular spherical shape to compacted mass which is due to polymeric transformation with increase in curing time which also corroborate with mechanical properties such as compressive strength. DSC isotherms show oozing out of inbuilt water which has accumulated during condensation polymerization reaction. The strength level achieved for optimum combination of variable is found to be comparable to that of standard motar of grade (M15) as is used for constructional purpose.
Properties of Geopolymer Concrete Produced by Silica Fume and Ground-Granulated Blast-Furnace Slag
In the construction industry, the main production of Portland cement causes the emission of air pollutants which results in environmental pollution. Geopolymer Concrete (GPCs) is a one type class of concrete based on an inorganic alumino-silicate binder system compared to the hydrated calcium silicate binder system of concrete. It possesses the advantages of rapid strength gain, elimination of water curing, good mechanical and durability properties and is eco-friendly and sustainable alternative to Ordinary Portland Cement (OPC) based concrete. This paper presents, to investigate the compressive strength of the Geopolymer concrete produced by replacement of Ground-granulated blast-furnace slag (GGBS) with SF (Silica fume) by 0%,20%,40%,60%,80% and 100% , and its studies carried out in varying molarity. The alkaline liquids were used in this study for the geopolymerization are sodium hydroxide (NaOH) and sodium silicate (Soi 2). The geopolymer concrete specimens were tested for their compressive strength at the ages of 7, 14 and 28 days under two types of curing (water curing and room curing). Experimental investigations have been carried out on workability, the various mechanical properties of GPCs.
Development of construction materials from the geopolymerization of red clay and coal fly ash
BIBECHANA
Red clay contains solid aluminosilicate has been shown to be reactive in the presence of an alkaline activator. The addition of coal fly ash and lime has shown improvements in their mechanical and physical properties of the geopolymer products. FTIR analysis and SEM images of the product have shown the formation of aluminosilicate gel in the geopolymeric product. The maximum compressive strength of the geopolymer products GP-RFL was achieved to be 15.92 N/mm2 having water absorption of 10.47 % and bulk density 2.81 g/cm3. These results indicated that geopolymer mortars made from red clay, coal fly ash and lime could be used as an alternative construction material./p> BIBECHANA 19 (2022) 119-126
Geopolymer Concrete - A Brief Review
2014
Large quantities of Portland cement is one of the major generator of carbon dioxide, into the atmosphere causing environmental problems and In addition to that large amount of embodied energy also being consumed for the cement production and also consumes huge amount of the natural resources i.e. limestone and fossils fuel but also produces almost 0.9t of CO2 for 1t cement clinker production. Also world cement production generates 2.8 billion ton manmade greenhouse gas annually on the other side abundant availability of fly ash worldwide creates opportunity to utilize (byproduct of burning coal, regarded as a waste material) as substitute for OPC to manufacture concrete solving the disposal problem and substitute to concrete by an eco friendly and sustainable material similar to conventional concrete. Geopolymer or inorganic alumino-silicates polymer is synthesized from predominantly silicon and aluminum materials of geological origin or by product materials, such as fly ash with alkaline liquids such as a combination of Sodium Silicate and Sodium Hydroxide. The chemical composition of geopolymer is similar to that of zeolite, but amorphous in microstructure. Flyash-based geopolymer binders show excellent short and long-term mechanical characteristics and similar or even better to conventional concrete and geopolymers are much superior to aggressive environment and fire than conventional concrete.
Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications
Review Paper, 2023
The advancement of eco-friendly technology in the construction sector has been improving rapidly in the last few years. As a result, multiple building materials were developed, enhanced, and proposed as replacements for some traditional materials. One notable example presents geopolymer as a substitute for ordinary Portland concrete (OPC). The manufacturing process of (OPC) generates CO2 emissions and a high energy demand, both of which contribute to ozone depletion and global warming. The implementation of geopolymer concrete (GPC) technology in the construction sector provides a path to more sustainable growth and a cleaner environment. This is due to geopolymer concrete's ability to reduce environmental pollutants and reduce the construction industry's carbon footprint. This is achieved through its unique composition, which typically involves industrial byproducts like fly ash or slag. These materials, rich in silicon and aluminum, react with alkaline solutions to form a binding gel, bypassing the need for the high-energy clinker production required in OPC. The use of such byproducts not only reduces CO2 emissions but also contributes to waste minimization. Additionally, geopolymer offers extra advantages compared to OPC, including improved mechanical strength, enhanced durability, and good stability in acidic and alkaline settings. Such properties make GPC particularly suitable for a range of construction environments, from industrial applications to infrastructure projects exposed to harsh conditions. This paper comprehensively reviews the different characteristics of geopolymers, which include their composition, compressive strength, durability, and curing methods. Furthermore, the environmental impacts related to the manufacturing of geopolymer materials were evaluated through the life-cycle assessment method. The result demonstrated that geopolymer concrete maintains positive environmental impacts due to the fact that it produces fewer carbon dioxide CO 2 emissions compared to OPC concrete during its manufacturing; however, geopolymer concrete had some minor negative environmental impacts, including abiotic depletion, human toxicity, freshwater ecotoxicity, terrestrial ecotoxicity, and acidi-fication. These are important considerations for ongoing research aimed at further improving the sustainability of geopolymer concrete. Moreover, it was determined that silicate content, curing temperature, and the proportion of alkaline solution to binder are the major factors significantly influencing the compressive strength of geopolymer concrete. The advancement of geopolymer technology represents not just a stride toward more sustainable construction practices but also paves the way for innovative approaches in the field of building materials.
This work presents the results of a study on reusing red mud (RM), an abundant alumina refinery waste produced by the Bayer process, and rice husk ash (RHA), a major waste from combustion of rice husk, as raw materials for the production of geopolymers that are environmentally friendly and only require low energy to make and have diverse potential applications. A wide range of parameters in the geopolymerization reaction, consisting of RHA to RM weight ratio, different particle size of RHA, and variable concentrations of sodium hydroxide solution, were examined to understand their influence on the compressive strength of the end products -RM&RHA-based geopolymers. The composition of RM, RHA, and RM&RHA-based geopolymers was characterized by X-ray diffraction. Moreover, the results of unconfmed compression testing indicate that the compressive strength of the studied RM&RHA-based geopolymers is in the range of 3.2 to 20.5 MPa, which is comparable with that of almost all Portland cements. In addition, the utilization of RM&RHA-based geopolymers in practice is able to bring both environmental and economic advantages. The findings suggest that these two plentiful wastes, RM and RHA, can be reused to make geopolymers that can find applications in civil infrastructure constructions.