Alkali-Silica. Reaction Of Foamed. Concrete Containing. Waste Glass as Aggregate

This research focused on examining Alkali-Silica. Reaction (ASR) of foamed concrete mixes containing1different1types of1crushed waste glass (CWG) with different chemical compositions. The reactivity was determined in sodium hydroxide solution by adopting mortar bar test. Four types of waste glass with different particle sizes and different percentages content were used. From the test results of recorded expansion of these mixes, it was noticed that the coarse glass resulted in more expansion than that of fine glass. Lead-silicate1glass (CR) exhibits the maximum expansion followed by1soda-lime1glass (SL) and boro-silicate glass (BS), while less expansion was recorded in mixes with green glass (GG). As compared to reference mix (FC), it was noted that the mixes with crushed waste glass (SL), (BS), and (CR) undergo notable expansion, while the expansion of the mixes with (GG) slightly increased compared to the reference mix (FC).

Effect of Fine Glass and Quartzite Powder on Microstructure and Strength Properties of Concrete

Concrete is a vital construction material. It consumes a high number of natural resources like water, sand, and stones. Due to the increase in human population, the demand for new construction is at its peak and increasing day by day. Due to this, we utilize many natural resources. Researchers and scientists are searching for different ways in which they can reduce the amount or find alternates for use of other materials in the manufacture industry. The use of waste materials is one of them. In this, research has been done by using Waste glass powder and Quartzite powder in concrete to find alternates or partial replacements for natural resources in concrete. It was found that the joined effective use of glass powder and quartzite powder in concrete permitted the substitution of up to 15% glass powder and 30% quartzite powder. Various effects of these materials on concrete are discussed like effects on strength Characteristics, and microstructure studies like X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). This study includes research and literature study from various journals paper and then the conclusion was made up.

An Experimental Study for Optimal Usage of Powdered Glass in Concrete as a Cement Replacement Material

The adverse effect of greenhouse emissions like CO2 leads to global warming. As per statistics, the global contribution of the cement manufacturing industry to greenhouse gas emissions is nearly 7%. To address these effects on the nature of the environment associated with cement manufacturing, it is necessary to explore sustainable binders for manufacturing concrete. Hence, extensive research is being conducted in the recent past to replace cement with various materials including waste generated from various sectors. Further, the replacement of fine aggregates and cement in concrete with various proportions of powdered glass is an engrossing topic among researchers for over a decade. The present study aims to the optimal use of glass powder in concrete as a replacement for cement and to enhance the characteristics compressive strength when compared to conventional concrete. Cement was replaced by various percentages of fine glass powder ranging from 10-50 % at an increment of 10%. The concrete cube specimens for 7 and 28 days were evaluated for their compressive strength after curing period, with that of conventional concrete. From the acquired results, it is perceptible that glass powder can be a suitable replacement for cement.

Effects of Recycled Fine Glass Aggregates on Alkali Silica Reaction and Thermo-Mechanical Behavior of Modified Concrete

The objective of this work is to develop a new composite material by substituting sand with recycled waste glass (RWG). Different volume percentages of RWG varying from 0 to 50% were incorporated into concrete, with maximum size that did not exceed 1.25 mm. The microscopic characterization by scanning electron microscopy SEM-EDS and optical microscopic test, as well as the durability against alkali silica reaction (ASR) test, were performed respectively to visualize the morphology and assess the damage caused by ASR. Furthermore, the mechanical and thermophysical properties measurements were carried out. The results of microscopic characterization showed the presence of cracks inside a minority of glass particles due to ASR, and ASR test indicated that expansion activity remained well below the limit expansion value of 0.15%. The obtained results also showed that, at 28 and 90 days of curing, compressive strength increased respectively by up to 1.63% and 29% for 20% of the incorporated RWG volume rate in concrete; however, beyond this rate it diminished receptively by 30% and 3.2%. This improvement with curing age was attributed to pozzolanic reaction. Regarding density, it reduced by around 5%. Furthermore, thermal conductivity and thermal effusivity decreased respectively by 36% and 8.06% at dry state and they dropped respectively by 44% and 21.28% at saturated state, related to reference concrete RC. It is therefore feasible to substitute high amount of natural sand with RWG to obtain new composite that may be successfully used as structural material in construction building.

Fabrication of Ultranarrow Nanochannels with Ultrasmall Nanocomponents in Glass Substrates

Nanofluidics is supposed to take advantage of a variety of new physical phenomena and unusual effects at nanoscales typically below 100 nm. However, the current chip-based nanofluidic applications are mostly based on the use of nanochannels with linewidths above 100 nm, due to the restricted ability of the efficient fabrication of nanochannels with narrow linewidths in glass substrates. In this study, we established the fabrication of nanofluidic structures in glass substrates with narrow linewidths of several tens of nanometers by optimizing a nanofabrication process composed of electron-beam lithography and plasma dry etching. Using the optimized process, we achieved the efficient fabrication of fine glass nanochannels with sub-40 nm linewidths, uniform lateral features, and smooth morphologies, in an accurate and precise way. Furthermore, the use of the process allowed the integration of similar or dissimilar material-based ultrasmall nanocomponents in the ultranarrow nanochannels, including arrays of pockets with volumes as less as 42 zeptoliters (zL, 10−21 L) and well-defined gold nanogaps as narrow as 19 nm. We believe that the established nanofabrication process will be very useful for expanding fundamental research and in further improving the applications of nanofluidic devices.

Developing a Sustainable Concrete using Waste Glass and Rubber for Application in Precast Pedestrian Slabs

In this piece of research, n attempt was made to produce a sustainable concrete with the partial replacement of both fine and coarse natural aggregates with two different non-biodegradable wastes. The selected wastes were fine glass and shredded rubber tires. Fine glass passing through 4.75 mm BS sieve was utilised for the partial replacement of fine natural aggregates. Coarse natural aggregates were partially replaced with shredded rubber passing through 20 mm sieve and retained on 6.30 mm sieve. Several mixes with varying % of fine glass but with a fixed 10 % of shredded rubber were tested. Optimum fine glass content was determined to be in the order of 20 %. The resulting concrete exhibited lower plastic and hardened densities (2040 and 2117 kg/m3 respectively) in comparison to normal plain concrete. The static modulus of elasticity was found to be 18.3 GPa (mean value), while the splitting tensile strength was 2.37 MPa. The flexural strength showed a significant increase of 20.3% compared to the control mix. The results concluded that the concrete thus produced is a viable means of disposing of such non-biodegradable wastes (rubber and glass), thus reducing the loads at landfills. This new genre of concrete was produced at a lower cost than normal concrete because of the very low pre-treatment costs of the recycled wastes used. Furthermore, the properties tend to indicate that the concrete could be applied where lower strength and high durability properties are warranted. Hence precast slabs were made from the new design concrete and were tested along a stretch of a highly trafficable pedestrian walkway on the University campus. The slabs were continuously monitored for defects such as cracks, broken corners and slabs for a period of 24 consecutive weeks. After the test period it was observed that only 4 out of the 80 precast slabs had hairline cracks. Hence concluding the enhanced durability properties of the new design concrete. Doi: 10.28991/cej-2021-03091690 Full Text: PDF

Biosilicate® Glass-Ceramic Foams From Refined Alkali Activation and Gel Casting

Biosilicate® glass-ceramics are among the most valid alternatives to 45S5 Bioglass. They combine a similar bioactivity and bioresorbability as the 45S5 with superior mechanical strength, owing to the crystallization of a Na–Ca silicate phase. This crystallization may be experienced upon viscous flow sintering of fine glass powders, thus configuring a sinter-crystallization process. As crystallization is seldom complete, sintering can also be applied to semicrystalline powders. The sintering/crystallization combination may be exploited for shaping highly porous bodies, to be used as scaffolds for bone tissue engineering, in the form of foams. The present study aims at exploring a gel-casting process, based on the room temperature foaming of powders suspended in a “weakly alkaline” (1 M NaOH) aqueous solution, followed by sintering at 1,000°C. The gelation of suspensions is attributed to the formation of hydrated compounds, later decomposed upon firing. Amorphous powders provided more intense gelation than semicrystalline ones, promoted a more homogeneous foaming, and stimulated a substantial crystallization upon firing. The homogeneity of foamed samples was assessed using micro-tomography and was further improved by casting foamed suspensions (“foam casting”) before setting.