Waste Glass Cullet Research Articles

Evaluation of the ASR of waste glass fine aggregate in alkali activated concrete by concrete prism tests

This paper examined the alkali–silica reaction (ASR) of waste glass cullet in alkali activated concrete (AAC), using the ASTM C1293 concrete prism test (CPT), in comparison to that in ordinary Portland cement (OPC) concrete. Test results showed that the 1-year expansions of OPC concrete and ground granulated blast furnace slag (GGBFS) based AAC were 0.21% and 0.13%, respectively, which exceeded the 0.04% limit of the ASTM standard. However, both fly ash (FA) based AAC and FA-GGBFS blended AAC showed 1-year expansions below the recommended limit. The AAC with 60% GGBFS and 40% FA showed the lowest 1-year expansion of all the concretes studied. The expansions showed consistency with the physical appearance, porosity and hydroxyl ion (OH–) concentration in the solution extracted from the concrete samples. Moreover, a detailed microstructural investigation revealed severe deterioration of glass aggregates when used in both OPC concrete and alkali activated GGBFS concrete due to the formation of calcium (Ca) rich expansive ASR gel. However, the gels formed at the aggregate paste interface of alkali activated FA and FA-GGBFS concrete were not typical ASR gels, since they contained high Al/Si ratios and low Ca/Si ratios.

Reuse of Heat Resistant Glass Cullet in Cement Composites Subjected to Thermal Load.

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article.

Effect of waste glass fine aggregate on the strength, durability and high temperature resistance of alkali-activated fly ash and GGBFS blended mortar

Properties of alkali-activated fly ash and GGBFS blended mortar using waste glass cullet were investigated. Workability of mortar was found to increase by glass aggregate due to its lower absorption than sand. Compressive strength decreased from 77 MPa to 73 MPa at 90 days of age for replacing 100% sand by glass aggregate. Though porosity increased by 1.5% to 13% for using 25% to 100% glass aggregate, reductions were observed in drying shrinkage, sorptivity and chloride permeability. The minor variations in mortar properties are attributed to the lower permeability and irregular shape of glass aggregate. Mortars using glass aggregate showed similar trend of residual strength as compared to that using natural sand after 200°C–800°C temperature exposures. Microstructural studies revealed that mortars using glass aggregate had less microcracks and enhanced bond at the interfacial transition zone (ITZ) after elevated temperature exposures. Moreover, the findings of this study suggests that the replacement of natural sand by using various percentages of waste glass cullet in alkali-activated mortar offers comparable properties to those using natural sand.

The effect of nanomaterials as anti-stripping additives on the moisture sensitivity of glasphalt

Despite the environmental and economic benefits of using glasphalt, it suffers from a number of disadvantages. The most common damage in glasphalt is the effect of water on bitumen-aggregate adhesion and the occurrence of moisture damage. One way to improve the resistance of glasphalt against the moisture damage is to use anti-stripping additives. Accordingly, the effect of two types of nanomaterials including nano hydrated lime (NHL) and nano calcium carbonate (NCC) as bitumen modifiers on the moisture sensitivity of glass asphalt has been investigated in this study. The moisture sensitivity of asphalt mixtures was assessed by the AASHTO T283 test and surface free energy (SFE) method. Indirect tensile strength (ITS) results show that the use of waste glass cullet increases and decreases the resistance of asphalt mixture in dry and wet conditions, respectively. An increase in the number of freeze–thaw cycles causes a decrease in the ITS of the glasphalt. The obtained results showed that using both nanomaterials in glasphalt significantly improved the resistance to moisture sensitivity. Bitumen modification using NHL and NCC, which was added in 2% bitumen, reduced the SFE of cohesion, which resulted in improving the bitumen coating on the aggregate surface and the adhesive between bitumen and aggregate.

Improvement on the properties of waste glass mortar with nanomaterials

Nowadays, nano materials were proved to be able to improve the properties of mortar, especially for recycled mortar with poor properties. In this study, nano-silica (nS) and nano-clay (nC) were used in waste glass mortar, with an additional amount of nS or nC varied from 0% to 6% of binder content by weight. Waste glass cullet was used as fine aggregate to fully replace natural sand in waste glass mortar. The properties of fresh and hardened waste glass mortar with or without nS/nC, including the early stiffening, flowability, density, compressive and flexural strength, shrinkage and alkali-silica reaction, were experimentally examined in this study. In addition, the pore size distribution of waste glass mortar was studied by using the mercury intrusion porosimetry test to build the relationship between microstructure and macro properties. The results show that nC has a greater effect on the early stiffening and flowability of mortar than nS. The defining pore structure and denser microstructure lead to the higher density and mechanical properties of mortar with nS/nC. nC is more beneficial for improving the 28-day compressive strength of glass mortar at a very small amount, whereas, the effect of nS on the strength at early ages of glass mortar is clearer. The incorporating use of 1% nS/nC have similar effect on suppressing the drying shrinkage but quite different influence on the ASR expansion. The additional use of 1% nS can increase the ASR expansion of glass mortar while 1% nC suppressed the expansion by 43.6% at 28-day.

Synthesis of Al-substituted 11Å tobermorite using waste glass cullet: A study on the microstructure

Calcium silicate hydrate (CSH), the key by-product of Portland cement hydration, due to the structural resemblance, is mainly represented as a defect tobermorite analog. To provide an extensive overview on the impact of Al incorporation in CSH, synthesis of Al-substituted 11 Å tobermorite using waste glass cullet (WGC) was investigated and compared with an Al-free reference. The optimal parameters of 180 °C curing temperature, 5h curing time, 0.5 M of activator concentration, and Ca/Si of 0.83 were found via XRD to synthesize pure crystalline tobermorite. SEM micrographs also showed that Al incorporation changed the tobermorite morphology from platy-like shape to acicular crystals. The WGC synthesized tobermorite exhibited similar thermal behavior to reference tobermorite as observed via TGA/DSC such as the free water release at 55 °C, interlayer water release at 131 °C, Si–O–H bond cleavage at 680 °C, and recrystallization to wollastonite at 820 °C. 29Si and 27Al NMR analysis showed that Al substitution preferably occurred at bridging (Q2) and branching (Q3) positions. The results from this study could significantly contribute to the application of Al-based wastes in concrete and mortar construction to improve the microstructure of the hydration by-products.

Optimizing the use of recycled glass materials in alkali activated cement (AAC) based mortars

The management of waste glass generated mainly from waste glass beverage bottles has become a pressuring waste management problem. This study presents a novel way to incorporate recycled glass materials into alkali-activated cement (AAC) based pastes/mortars. Waste glass cullet (GC) was used to replace natural aggregates and waste glass powder (GP) was used to partially replace conventional precursors such as ground blast furnace slag (GGBS). Optimization was conducted innovatively aiming at maximizing the total waste glass content in the AAC materials while maintaining adequate mechanical, durability and functional properties of the final products that contained more than 70% of recycled glass materials by mass. Using the developed technology, recycled glass incorporated alkali activated cement based mortars (AAMs) with a 28-day compressive strength of about 40 MPa can be produced. Furthermore, the excellent high temperature resistance of the optimized AAC mortar mixture allowed the retention of over 50% of the original strength after 2 h of exposure at 800 °C. The experimental results also showed that the detrimental expansion caused by the alkali silica reaction (ASR) between the alkali and the waste GC in the AAC mortars could be controlled successfully by using additional aluminium sources such as calcium aluminate cement (CAC). Further reduction in ASR expansion was possible via adjusting the GC to binder ratio. Also, the drying shrinkage level could be controlled to less than 1000με which is a significant improvement to conventional AAC materials prepared by using GGBS. The findings presented in this paper are pivotal for maximizing the recycling and reusing of waste glass in AAC.

The influence of ground waste glass cullet addition on the compressive strength and microstructure of Portland cement pastes and mortars

The paper presents a study on the infl uence of ground waste glass cullet, introduced as a component of Portland cements in the amounts of 5% and 35% by mass, on the properties of pastes and mortars. The pozzolanic nature of the additive was confirmed – the long-term compressive strength of cement composites has incre-ased, compared to the reference sample. However, a decrease in the early compressive strength was observed. Replacing part of the Portland clinker with ground waste glass cullet resulted in the reduction of the heat of hydration. It was determined that the degree of grinding has a signifi cant impact on the activity of waste glass cullet – in the case of the cullet ground to 5000 cm2/g, the beginning of the pozzolanic reaction was observed after 7 days, whereas for the cullet ground to 3000 cm2/g, the reaction was severely delayed. In the course of one year, no negative impact of the alkali-silica reaction on the strength and microstructure of mortars and pastes was observed, however, a longer study needs to be conducted to verify the results. The research proves that waste glass cullet can be potentially used as a main component of Portland cements, with no adverse effects on the properties of the composites.

METALLURGICAL WASTE VALORIZATION FOR FABRICATING GLASS-CERAMICS MATERIALS

The valorization of a metallurgical waste (i.e., an iron-rich slag) as raw material for the fabrication of high hardness glass-ceramics using differential thermal analysis, X-ray diffraction, X-ray fluorescence and scanning electron microscopy was investigated. The melting of the slag was aided by the addition of waste glass cullet (WGC) and the vitrification field of this system was investigated. The non-isothermal crystallization kinetics of the parent glass with the highest slag content was studied by DTA and crystallization of the parent glasses led to of pyroxenic crystalline phases, suggesting the application of the obtained glass-ceramics as building materials. Environmental benefits such as the reduction in the consumption of virgin raw materials and the elimination or reduction of CO2 and SO2 emissions due to absence of carbonates and sulphates in the batch composition make it an interesting alternative for the application of this technology.

Co-utilization of waste glass cullet and glass powder in precast concrete products

This study aimed at developing an eco-friendly precast concrete product by enhancing the application of waste glass. The waste glass was utilized as both fine aggregates and a partial binder in the form of glass powder (GP) in the paving blocks. The results showed that the strength was constant despite increasing amount of glass cullet (GC) was used in the paving blocks. The combined use of GC and fine GP was beneficial in reducing the water absorption and drying shrinkage of the paving blocks within permissible limits. Moreover, the addition of GP could successfully address the concern of ASR expansion resulting from GC.

Sustainable design of pervious concrete using waste glass and recycled concrete aggregate

This study designed an eco-friendly pervious concrete (PC) product using waste glass cullet (WGC) and recycled concrete aggregate (RCA) by dry-mixed compaction technique. The mechanical properties, water permeability behavior and related pore structure characteristics, thermal conductivity of the PCs were determined. The experimental results showed that the use of silica fume in the cement paste was effective to compensate for the low compressive strength of the PCs due to the use of narrowed graded aggregates without the incorporation of fine particles (less than 2.36 mm). Although the incorporation of recycled aggregates (i.e. WGC and RCA) into the PCs led to reductions in compressive strength, the water permeability of the PCs was improved, especially for the PCs prepared with WGC, as the use of WGC was conducive to improving the water permeability due to the negligible water absorption nature and smooth surface of glass cullet. Another encouraging result indicated that the PCs comprising 50% WGC as the fine aggregate and 50% RCA as the coarse aggregates could achieve satisfactory strength and permeability, which could largely meet the requirement of the standard (JIS A 5371) for permeable pedestrian pavers. The appropriate blending of the selected size of WGC (2.36–5 mm) and RCA (5–10 mm) to produce a desirable pore structure in the PCs were responsible for the good performance. In addition, the low thermal conductivity of the produced PCs provided an opportunity to use the PC as partition block materials for saving energy consumption of buildings.

Post-consumer cullet and potential engineering applications in North America

Waste glass cullet (WGC) recovered from almost all waste streams is contaminated with mixed-color sources of variable compositions. Consequently, over 60% of the cullet is discarded in landfills in North America. The present work provides an overview of the potential end markets for the cullet with a focus on collection systems, marketing strategies, safety and environmental issues as well as the economics of the target applications. Cullet can find major applications in construction industry as a substitute to natural aggregates integrated with different proportions of concrete to build pavements, and roads Cullet could be widely used in different applications due to its desirable physical, mechanical, and chemical properties. This makes cullet an appropriate alternative for natural resources. Although various applications discussed in this paper have well-established markets, low proportion of cullet has been implemented in those applications. This could be attributed to the higher preprocessing cost of cullet compared to the natural aggregates. Different measures are required by the governments to continue to develop the potential post-consumer markets for recycled cullet such as encouraging recycling of WGC and restricting the use of landfilling activities for WGC.

Implications and characterization of waste glass cullet – kaolinite clay ceramics

Cullet(x) reinforced ceramics (100 – x) made from Ukpor kaolinite clay by dry-pressing and fired at temperatures (T 0 C) for 900≥T≤ 1250 0 C with 0≤x ≤40% wt was investigated for its ceramics application. The chemical profile of the samples (cullet and clay) was determined by Atomic Absorption Spectroscopy (A.A.S) technique. Mineral composition was determined by XRD while SEM was employed to view the phase modification. The particle size of the raw materials was maintained at <180μm. The mechanical properties, micro-structure, and phase composition are discussed with respect to cullet content and temperature variation. It was observed that production temperature decreased with increase in cullet. Micro-structural study showed a granulated morphology and the formation of phase-boundary as granules fuse due to clay cullet crystallization with increase in cullet and temperature. Electrical insulation is greatly improved while thermal insulation is reduced due to the closure of pores with increase in cullet and temperature respectively. The mechanical properties of flexural strength, porosity, bulk and apparent density, shrinkage and water absorption were greatly modified for every 10% increase in cullet content. Production temperature greatly reduced with increase in cullet suggesting longer lifespan for the kilns and furnaces used. The study supports the utilization of cullet in the production of ceramics, a good reason to recycle waste to wealth but in excess of 20% cullet, production temperature must not exceed 1100 0 C due to development of cracks. Keywords: Bulk Density, cullet; porcelain; porosity; Ukpor clay (U.C); temperature

Microwave synthesis of zeolites from waste glass cullet using landfill leachate as a novel alternative solvent

Abstract The present work investigated the microwave (MW) zeolitization of waste glass cullet using landfill leachate as a new potential solvent. The leachate-based zeolites were synthesized in two sets, one with metal precipitation and filtration (F-zeolite) and the second one with unfiltered metal precipitates (UF-zeolite). These two cases were compared with reference zeolites produced using deionized water (D-zeolite) in terms of their characteristics. Different characterization techniques were used including XRD, EDX, SEM, FTIR, TGA, and cation exchange capacity (CEC). Presence of cations other than Na+ in leachate elevated the generation of hot spot zones and synthesized highly crystalline zeolites using unfiltered leachate. Substantial reduction in Na+ concentration due to the solid filtration also favored the production of a roughly single-phase hydroxysodalite (HS) and suppressed zeolite NaP1 formation using filtered leachate. Deionized water also produced a small fraction of zeolite NaP1 due to the lower Na+ content compared to unfiltered leachate. Zeolite synthesized using unfiltered leachate was also superior in cation exchange and water holding capacities due to its least Si/Al ratio as confirmed by EDX, TGA, and CEC results. The results from this study contribute to shed light on the efficiency of leachate application for large-scale zeolite synthesis in future prospect.

Production of sodium silicate powder from waste glass cullet for alkali activation of alternative binders

A simple process to produce sodium silicate powder from glass cullet has been developed. A mixture of glass powder, sodium hydroxide powder, and water was heated at temperatures of 150 to 330 °C. The effects of glass to NaOH ratio, temperature and duration, inclusion of water and fineness of NaOH were investigated. Fly ash and fly ash/GGBS blends were the precursors for alkali activated binder (AAB) mortars produced with this sodium silicate. Compressive strengths were similar to or better than those obtained with commercially available sodium silicate and sodium hydroxide solutions. FT-IR tests suggested that the reactivity of the glass derived sodium silicate powder was related to the number of non-bridging oxygen atoms in the silicate structure. Cost comparison between AAB and Portland cement concretes gave similar results for normal strength concretes (35 MPa). AAB concretes with higher strengths (50 and 70 MPa) can be cheaper than equivalent traditional concrete.

Microwave synthesis of zeolites from waste glass cullet using indirect fusion and direct hydrothermal methods: A comparative study

The present work studied the conversion of waste glass (WG) cullet into zeolite using microwave (MW) radiation technique. The temperature and power of radiation were monitored through constant temperature (MWCT) and constant power (MWCP) modes. Indirect fusion synthesis (IFS) and direct hydrothermal synthesis (DHS) conversion methods were studied and the zeolites synthesized by these methods were compared in terms of their characteristics using various techniques including XRD, EDX, SEM, FTIR, TGA, and cation exchange capacity (CEC). IFS was an efficacious synthesis technique and produced zeolites with a much higher crystal growth efficiency compared with those synthesized by DHS method. The IFS method was better than the DHS method as it eliminated the inhibitive effect of soluble aluminates on Si release. The IFS zeolites also provided lower Si/Al ratio and consequently higher cation exchange and water holding capacities compared to DHS zeolites, as validated by EDX, TGA, and CEC results. In addition, high pressure and high-temperature environment deteriorated the zeolite structure and diminished the crystal growth performance. The application of cooling air jet (CAJ) through MWCP mode provided efficient monitoring of temperature overshoot and excessive pressure generation by cooling the excessive generated hot spot zones. Therefore, the CAJ application improved the crystal growth in IFS method as higher radiation powers were applied.

Cost-effective zeolite synthesis from waste glass cullet using energy efficient microwave radiation

Abstract A rapid zeolite synthesis procedure was investigated using pulverized waste glass cullet via microwave radiation and compared with zeolites synthesized using convection heating. It was observed that constant temperature microwave synthesis method made zeolites more efficiently under superheating conditions with a maximum relative crystallinity of 60%. The maximum relative crystallinity of the synthesized zeolites was found to be similar when convection heating and constant temperature controlled microwave synthesis was used; however, the latter technique offerred a factor of 140 reduction in synthesis time. This rapid synthesis process is attractive to the industrial application due to its high-energy efficiency.

Briquetting of waste glass cullet fine particles for energy saving glass manufacture

Fine particles of glass cullet (fines) arising during glass recycling cannot presently be recycled into glass manufacture due to the potential for bubble formation and foaming. Consolidation of glass fines into briquettes could enable their re-introduction into furnaces, reducing waste and glass melting energies. Properties of briquetted cullet fines and briquette melting behaviour in soda-lime-silica glass batches are presented. Morphology and density of glass fines and briquettes; and briquette mass and mechanical properties as functions of time after formation were analyzed. Compressive strength increases linearly with time after briquette formation. With slight batch modifications to maintain the same final glass composition, up to 15 wt % briquettes were successfully added to a representative container glass batch and melted. Results confirm that briquette batch additions can provide equivalent final glass composition, optical absorption characteristics and redox to briquette-free batches, supporting their industrial uptake.

Novel geopolymers incorporating red mud and waste glass cullet

Red mud presents significant environmental problems, so that its incorporation in geopolymers could represent an alternative solution to produce valuable products from this residue. Novel geopolymers using red mud as source of alumina and waste glass as silica supplier were developed, using sodium hydroxide as the only ‘non-waste’ material. The formation of a homogeneous polymeric gel, confirmed by solid-state NMR and EDX analysis, promoted the stabilization of possible pollutants. Moreover, the materials exhibit a remarkable compressive strength (up to 45 MPa, for 60 wt% red mud).

Fired ceramics 100% from lignite fly ash and waste glass cullet mixtures

In the present study, the development of new building ceramics is investigated, using 100% lignite fly ash (FA) and waste glass cullet (WGC) mixtures as secondary industrial raw materials towards circular economy. Thus, compacted and sintered (at 700 and 900°C) ceramic bodies based on binary WGC/FA mixtures, with WGC loadings up to 15%, were fabricated. The utilization of WGC (amorphous) aimed at lowering the sintering temperature of the mixture, for energy reduction purposes, via a better heat flux regulation in the material. The successful consolidation/densification of the ceramic microstructures, mainly composed of different silica phases, was achieved upon synergistic sintering at 900°C for 2h. Moreover, the successful consolidation/densification was confirmed by the SEM micrograph observation and the porosity evaluation from the SEM micrographs. The addition of WGC yielded to a drastic decrease in the porosity values (down to 12%) for the samples sintered at 900°C for 2h. This porosity decrease favored, in turn, the substantial microhardness increase (up to 3833 HV) due to the pore sealing by the glassy phase of WGC. Moreover, an exponential relationship between microhardness and porosity was revealed. Finally, further investigation of the processing conditions is currently underway towards the optimization of the attained ceramic microstructures in order to meet the requirements of specific applications.