Options to Improve the Mechanical Properties of Protein-Based Materials

While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.

Effect of Flyash- Rice Husk Ash Blend in the Energy Efficient Geopolymer Tiles Using Industrial Wastes

Infrastructural developments are inevitable for the developing countries and hence the production of sustainable building materials is promoted worldwide. Sustainable development in the vicinity of tiles is bewildered for more than a decade. Production of conventional tiles such as cement concrete tiles, clay tiles and ceramic tiles is energy intensive approach and levies lot of strain over the adjunct ecosystem. On the other hand there are serious problems related to the disposal of flyash, Rice Husk Ash throughout the world. An approach has been taken to synthesis tiles based on these industrial byproducts as the base materials through Geopolymer technology. In this work, Geopolymer mortar after heat curing is applied as tiles. In this work, Flyash is replaced by Rice Husk Ash in various proportions such as 20, 40, 60, 80 and 100 percent. Tests such as workability, flatness, straightness, perpendicularity, water absorption, modulus of rupture and abrasion are conducted and fair results are obtained. This research also portrays the effect of Rise Husk Ash addition over the flyash based Geopolymer binder in the utility as tiles. The findings of this research work encourages the development of energy efficient tiles using industrial wastes. Keywords: Geopolymer, Rice Husk Ash, Tiles

Flexural behavior of flat and folded geopolymer ferrocement panels

This paper presents the impact of fiber and wire mesh layers on the strength behavior of flat as well as folded fly ash-based geopolymer ferrocement panels. The behavior, including flexural strength, ductility, stiffness, and cracking patterns are observed. With an objective of decreasing CO2 emissions, the concrete utilizes wastes such as fly ash disposed by industrial sectors. Six panels (three flat and three folded) were cast utilizing fly ash dependent geopolymer mortar of size 1000mm x 400mm x 30mm. Heat curing in a temperature-controlled chamber maintaining 75○C to 80○C for 24 hours was done after 24 hours of resting period. The experimental results indicated that the flexural strength got enhanced by 33 percent by increasing the quantity of wire mesh layers, but the ductility got decreased by 30 percent for the flat panels; however, there was no noticeable impact in case of folded panels. The flexural strength of folded panels was found to be three times greater than that of flat panels. In addition, it is noticed that the behavior of fiber reinforced flat as well as folded panels of single layer mesh is stronger than double layer wire mesh panels with regard to cracking and ultimate load. The energy absorbed at failure was directly proportional to the volume of the reinforcement provided in the panels.

Strength Behavior of Flat and Folded Fly Ash-Based Geopolymer Ferrocement Panels under Flexure and Impact

This paper presents the impact of fiber and wire mesh layers on the strength behavior of flat as well as folded fly ash-based geopolymer ferrocement panels. The behaviors, namely, flexural strength, impact strength, ductility, stiffness, and cracking patterns, are observed. With the objective of decreasing CO2 emissions, concrete utilizes wastes such as fly ash disposed by industrial sectors. Six panels (three flat and three folded) were cast utilizing a fly ash-dependent geopolymer mortar of size 1000 mm × 400 mm × 30 mm in addition to two panels of each type for the impact study. Heat curing in a temperature-controlled chamber maintaining 75°C to 80°C for 24 hours was done after 24 hours of the resting period. The experimental results indicated that the flexural strength got enhanced by 33 percent by increasing the quantity of wire mesh layers, but the ductility got decreased by 30 percent for the flat panels; however, there was no noticeable impact in the case of folded panels. The flexural strength of the folded panel was found to be three times greater than that of the flat panels. In addition, it is noticed that the behavior of the fiber-reinforced flat as well as folded panels of single layer mesh is stronger than the double layer wire mesh panels regarding cracking and ultimate load. Furthermore, the impact strength of the folded panels was found to be 90% greater than that of flat panels, and the energy absorbed at failure was directly proportional to the volume of reinforcement provided in the panels. Moreover, the failure pattern of the impact tested specimens showed punching shear as the predominant factor.

Influence of Using Various Percentages of Slag on Mechanical Properties of Fly Ash-based Geopolymer Concrete

In order to implement the concept of sustainability in the field of construction, it is necessary to find an alternative to the materials that cause pollution by manufacturing, the most important of which is cement. Because factory wastes provide siliceous and aluminous materials and contain calcium such as fly ash and slag that are used in the production of high-strength geopolymer concrete with specifications similar to ordinary concrete, it was necessary for developing this type of concrete that is helping to reduce CO2 (dioxide carbon) in the atmosphere. Therefore, the aim of this study was to study the influence of incorporating various percentages of slag as a replacement for fly ash and the effect of slag on mechanical properties. This paper showed the details of the experimental work that has been undertaken to search and make tests the strength of geopolymer mixtures made of fly ash and then replaced fly ash with slag in different percentages. The geopolymer mixes were prepared using a ground granulated blast-furnace slag (GGBFS) blend and low calcium fly ash class F activated by an alkaline solution. The mixture compositions of fly ash to slag were (0.75:0.25, 0.65:0.35, 0.55:0.45) by weight of cementitious materials respectively and compared with reference mix of conventional concrete with mix proportion 1:1.5:3 (cement: sand: coarse agg.), respectively. The copper fiber was used as recycled material from electricity devices wastes such as (machines, motors, wires, and electronic devices) to enhance the mechanical properties of geopolymer concrete. The heat curing system at 40 oC temperature was used. The results revealed that the mix proportion of 0.45 blast furnace slag and 0.55 fly ash produced the best strength results. It also showed that this mix ratio could provide a solution for the need for heat curing for fly ash-based geopolymer.

Correlation Analysis of Heat Curing and Compressive Strength of Carbon Nanotube–Cement Mortar Composites at Sub-Zero Temperatures

Concrete curing under sub-zero temperatures causes various problems, such as initial cracking and a decrease in mechanical strength. This study investigated the effect of sub-zero ambient temperature and multi-walled carbon nanotube (MWCNT) content on the heat and strength characteristics of heat-cured MWCNT cementitious composites. The experimental parameters were the application of heat curing, MWCNT content, use of an insulation box to achieve a closed system, and ambient temperature. The results showed that the internal temperature change of the MWCNT cementitious composite increased with the ambient temperature and MWCNT content. When an insulation box was installed, the maximum temperature change of the MWCNT cementitious composite during curing increased. Furthermore, heat curing increased the compressive strength of the cementitious composite. Moreover, a microstructure analysis using field-emission scanning electron microscopy verified the formation of a MWCNT network among the cement hydrates.