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Article

Environmental Implications of Using Waste Glass as Aggregate in Concrete

by
Robert Lopez
1,* and
Charbel El-Fata
2
1
Construction Management Discipline, School of Design and the Built Environment (DBE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia
2
KBR Incorporated, GPO Box 1618, Sydney, NSW 2001, Australia
*
Author to whom correspondence should be addressed.
J. Compos. Sci. 2024, 8(12), 507; https://doi.org/10.3390/jcs8120507
Submission received: 23 September 2024 / Revised: 17 November 2024 / Accepted: 2 December 2024 / Published: 5 December 2024
(This article belongs to the Special Issue Novel Cement and Concrete Materials)
Browse Figures
Figure 1
<p>Survey respondent locations.</p> "> Figure 2
<p>Scree and Cut Off Point plot with factor numbers and eigenvalues.</p> "> Figure 3
<p>Production of fine aggregate and respondent numbers bar chart.</p> "> Figure 4
<p>Aggregate sources and respondent numbers bar chart.</p> "> Figure 5
<p>Production of coarse aggregate and respondent numbers bar chart.</p> "> Figure 6
<p>Loads of haulage (tons) and respondent numbers bar chart.</p> "> Figure 7
<p>Aggregate distribution (%) and respondent numbers bar chart.</p> "> Figure 8
<p>Distances of haulage (km) and respondent numbers bar chart.</p> ">
Versions Notes

Abstract

:
Approximately 10 billion tons of fine and coarse aggregate are manufactured worldwide annually, solely to be used as concrete for constructed structures. With approximately 80% of conventional concrete comprising sand and stone, activities in their extraction and relocation harm the natural environment. Manufacturing concrete causes substantial amounts of ecological damage and energy consumption. The replacement of natural aggregate with waste glass, therefore, theoretically removes this environmental damage and energy consumption. The research presented in this paper tested the theory that waste glass concrete aggregate represents a potential solution to curtail the adverse impact of concrete on the natural environment. Testing this theory entailed the review of the existing literature and analyses of the findings from a survey of 107 organizations situated in five countries within the concrete manufacturing supply chain. The findings of this research demonstrate that environmental implications exist with the use of both natural aggregate and glass waste. Significant CO2 reductions can be achieved by using glass as aggregate in concrete. This is found to be up to 60% and 65% for fine and coarse aggregates, respectively. In addition, using glass in its aggregate can potentially improve the strength of concrete. With a concrete grade of 20, an improved compressive strength test of up to 10 could be possible. Similarly, with concrete grades of 25 and 30, an improved tensile strength test of up to 9 could be possible. This depends on differences in the percentage of natural aggregate that has been substituted with glass.

1. Background and Introduction

Over 10 billion tons of structural concrete is used annually on construction sites around the world, with between 60% and 80% of this essentially made up of aggregate [1,2,3,4,5,6]. Aggregate is traditionally produced by crushing sand and rock, the processes of which have significant impacts on the natural environment. The idea to substitute natural aggregate with glass has been driven by the steady reduction in natural resources, as well as the recent sustainability initiatives of institutions and governments [7,8,9]. The environmental impacts of natural aggregate extraction and the suitability of glass as a replacement have previously been studied [4,10,11,12,13,14]. Around 80% of natural aggregate extracted throughout history has happened in the last century [9]. The continuous extraction of natural resources and waste glass has the following environmental impacts [1]:
  • The substantial energy consumption in extracting the raw material;
  • The high ecological damage to mined and extracted areas;
  • The fact that disposed waste glass retains its shape and does not biodegrade for centuries.
Waste glass is generated in large quantities within many countries. There is, therefore, a need for the circularity of waste glass to be considered. Many options currently exist for waste glass to be used in concrete. These include being in the form of either fine glass powder, as aggregates within structural/non-structural concrete; lightweight aggregate for the same; etc. Each application needs a different treatment of the waste glass. This includes grinding, extra crushing, sorting/sieving, melting, the production of lightweight glass aggregate, etc. In developed countries, over 15 million tons of waste glass is generated per year. Much of this is recyclable, crushable, and reusable as aggregate for concrete [15,16,17,18,19,20]. Sustainable practices in concrete are being embraced [21]. Likewise, the feasibility and suitability of glass concrete aggregate have previously been studied [4,10,11,12,13,14]. Waste glass is practical and feasible for use in concrete when combined with certain additives. Despite widespread interest in ecological protection, the previous research has generally focused on the following [4,10,11,12,13,14,22,23]:
  • The suitability of glass as concrete aggregate;
  • The environmental effects of extracting natural resources and recycling.
Recently, it was found that waste glass can be used as reinforcement in the construction of a fire-resistant concrete infill wall [24]. Additionally, it was found that incorporating waste-toughened glass can even provide concrete with high-performance properties [25]. These findings suggest that waste glass has diverse applications in concrete, not only for environmental sustainability but also for enhancing concrete performance in specialized construction scenarios, which broadens the potential applications of this material [24,25].

2. Research Aim, Objectives, and Purpose

It has been advocated that crushing natural aggregate consumes greater amounts of energy than producing their recycled counterparts [26,27]. It has also been advocated that the energy expended has been similar between producing natural and recycled concrete aggregate in general [3,28]. The benefits of substituting natural concrete aggregate with recycled glass remain unclear. The study presented in this paper aims to identify the environmental implications of producing both aggregates for concrete. Achieving this aim involved addressing the following research objectives:
  • Objective One—Identify the amount of impact in the natural environment the extraction of conventional concrete aggregate produces;
  • Objective Two—Determine the feasibility of substituting natural concrete aggregate with recycled glass;
  • Objective Three—Evaluate the ecological impacts of substituting natural concrete aggregate with crushed glass.
Understanding how the production of both conventional and recycled glass aggregates relates to the natural environment enables companies within the concrete supply chain to be better informed in their decision-making. Furthermore, a better understanding of the ecological impacts of both aggregates can improve the environmental sustainability policies of these companies.

3. Natural Aggregate in Concrete

Concrete is among the world’s greatest-produced building materials [1,2,3,4,5,6]. Of natural resources extracted throughout history, approximately 80% has been within this last century [8]. Approximately 40% is estimated to have happened in Europe [7]. The need to curtail the impacts of concrete on the natural environment and the engineering challenges of providing for ecologically sustainable development (or ESD) had previously been recognized [21]. Aggregates make up between 60% and 80% of the concrete volume in total, with the rest comprising water, cement, and additives [1]. Concrete salvaged from construction and demolition (or C&D), as well as tires, can also be recycled into aggregate [29].

4. Glass Waste Suitability

4.1. State-of-the-Art Overview

Within the last five years, the latest findings from researchers in the field of sustainable concrete practices can be found [24,25,30,31,32,33,34,35,36,37]. The performance of concrete can vary with the use of waste glass either in powder, sand, or cullet form [34]. It is already known that using recycled glass in producing concrete can improve its environmental sustainability performance by approximately 8% [31]. Adding glass powder to concrete can improve its durability performance [32]. Waste glass can partially substitute the cement content in ultra-high-performance concrete [35,37], even if it contains fly ash and silica fume [36]. For example, reinforced concrete beams that incorporate waste glass powder can still have satisfactory flexural performance [30]. Recycled waste glass powder is also a good replacement for sand in concrete [33].

4.2. Municipal Waste Glass

In 2013, the USA generated 251 million tons of municipal waste [18,20,38]. Approximately 5% or 11.5 million tons of this was waste glass [18]. In comparison, Australia’s waste generation has been consistent with its population growth. This, in turn, means that greater amounts of wastage are being generated each year [39]. Table 1 presents the statistics of glass from municipal waste generated and reported in Australia, Canada, New Zealand, the UK, and the USA. It shows that these five countries combined generated over 10 million tons of unrecycled glass from municipal waste [15,16,17,18,19,20,40].

4.3. Waste Glass Suitability as Concrete Aggregate

Some salvaged glass was tested as fine aggregate inside 30 MPa, 45 MPa, and 60 MPa compressive strength concrete. After 90 days of curing time, concrete containing the glass had increased strength in compression and tension than its conventional counterpart which contained natural sand as the fine aggregate [14]. Glass tested as both fine and coarse aggregate in concrete also found similar increases in strength [13].
Contrastingly, it was found that using glass bottles reduced concrete strength in compression by approximately 30% relative to its conventional counterpart which contained natural rocks as the coarse aggregate [4]. A reduced concrete strength in compression was also found, as well as malleability and slump, the more glass aggregate it contains [10]. Collectively, these previous studies determined that the use of glass as aggregate reduces concrete strength in compression and malleability. Despite this, such reductions did not hinder its feasibility for use in various concrete applications [7,10,11,41].
From slump testing, the reduced strength was found to be caused by glass having sharp edges, angled shapes, and smooth surfaces [10,42,43]. Moreover, a study went so far as to use a “scanning electron microscope” to observe that the surface contact between cement and fine glass aggregate particles was indeed sometimes inadequate. An inadequate bonding strength between both particles can increase the risk of cracking [42]. To mitigate the risk of concrete cracking, replacing 25% of cement with fly ash as an additive has been suggested [12,44]. The use of glass as fine aggregate and fly ash together has been examined [45,46]. Consistent with the previous findings [12,44], it was also found that fly ash serves to reduce the alkali–silica reaction (ASR) of the glass aggregate and cement in the concrete mixture [45,46].

4.4. Alkali–Silica Reaction

The feasibility of replacing natural aggregates with waste glass is possible. Yet, there are technical problems to address. These problems include the ASR. Some methods exist to avoid this phenomenon. The ASR happens when hydroxyl ions of cement chemically react to the silica of glass [47]. The CR2O3 chemical in green glass will increase the ASR intensity when combined with cement within a concrete mixture [48]. Contrastingly, concrete was not found to expand when it contained colored glass as its aggregate [49,50]. It is possible to avoid the ASR if the glass aggregate used is finer than 1 mm/300 μm in diameter [4,14,40,51]. The ASR could also be avoided by including other additives in the concrete mix like lithium carbonate or metakaolin [10,44,48,49,52].

4.5. Pozzolanic Activity of Fly Ash

Fly ash is the byproduct of coal-burning facilities that generate power. It primarily contains aluminum, silicon, calcium, and iron oxides. Fly ash also has pozzolanic properties. When 25% of the cement ratio is replaced with fly ash, the concrete will then possess greater bonding properties between its ingredients, as well as strength in indirect tension and compression [44]. It has been established that its use will, in turn, reduce the ASR and is, therefore, beneficial in concrete when using glass as the aggregate [29,43,44,45,46,51,53].

5. Effects on the Natural Environment

5.1. Natural Aggregate Carbon Emissions

The quarrying of sand or rock for use as concrete aggregate consumes substantial amounts of energy and is destructive to the natural environment of the land where they are quarried [54]. Rock requires more energy to process than sand, as crushing is also involved [23]. The carbon dioxide (CO2) emitted from quarrying natural aggregates ranges between 13.9 kg/ton for sand and 45.9 kg/ton for granite coarse aggregate [55]. Despite these emissions, the use of sand has still been deemed environmentally friendly as it tends to be devoid of crushing, which means that their processing only requires approximately [6,22,23,55]:
  • 30% of the energy needed to process granite;
  • 40% of the energy needed to process basalt.
Quarrying and crushing 1 ton of basalt for aggregate emits 1.5 kg of CO2 from approximately 74% of the electricity used. This emission can vary slightly based on the duration differences of batching methods [6,55].

5.2. Glass Aggregate Natural Environmental Impacts

The recycling of waste glass for use as aggregate in concrete contributes toward ESD by serving to reduce quarrying and landfill [42,56]. In recycling, melting glass again leaves less of a carbon footprint than crushing it [26,27]. It has been established that substituting new with recycled glass can reduce the energy otherwise consumed in manufacturing by 27% and the resultant emissions by 37% [57].
The energy expended has been similar between producing natural and recycled concrete aggregate in general [3]. An exception to this is the substitution of natural aggregate with recycled glass, which uses less energy [2,28,58]. In addition, glass recycling is economically viable in locations where the availability of land is scarce [2].

6. Research Methodology

6.1. Research Philosophy

The research presented in this paper encompassed the development of existing knowledge obtained from relevant sources [59]. A set of methods had been selected to research the issue at hand [60]. New knowledge has been acquired with a philosophy based on constructivism and epistemological positivism. The following epistemological knowledge areas are therefore applied in this research [59]:
  • Intuition;
  • Authoritativeness;
  • Logic;
  • Empiricism.
Knowledge is not necessarily obtained scientifically. The philosophy adopted sought to test existing theories based on reliability, validity, observations, and information to draw accurate conclusions [59]. The benefit of using statistical methods to analyze data is the numerical emergence of relationships and patterns [60].

6.2. Research Design and Methods

The quantitative data gathered were used in a number of ways [61,62]. This non-experimental descriptive study is ideal for finding features of an entire industry by surveying a small representative group using a questionnaire [61]. This research is cross-sectional as the field data were gathered during a particular period [62]. Companies in the concrete supply chain for construction had been invited to participate in this questionnaire-based survey, either via phone or email. Administering the questionnaire via email and the Internet enabled the greater amount of randomness, as well as diversity, of respondents to be sampled [63]. The following questions sourced from the questionnaire that was sent to and asked of the companies, the answers to which then underwent data analyses, are specifically as follows, verbatim:
  • “What type of aggregate do you use in your concrete?” (Question 1);
  • “How much fine aggregate is produced on a daily basis (in tons)?” (Question 2);
  • “How much coarse aggregate is produced on a daily basis (in tons)?” (Question 3);
  • “Where does the aggregate source come from?” (Question 4);
  • “Please specify how far the average km of travel distance is between the source and the manufacturing plant” (Question 5);
  • “How many tons of aggregate does each load hold (ship or truck load)?” (Question 6);
  • “What is the typical mix in a % between coarse and fine aggregates usually used for all different strengths of concrete?” (Question 7);
  • “Prior to this survey, did you know that the use of glass in structural concrete is feasible?” (Question 8);
  • “In regard to the use of aggregate, does your company maintain any environmental standards?” (Question 9); as well as
  • “In regard to the use of aggregate, do you believe that there needs to be a higher focus on the environment?” (Question 10).
In addition, quantitative data were also obtained from previous researchers of glass as concrete aggregate. These data underwent further comparative analyses with the minimum requirements [64,65], to determine the suitability of glass aggregate.

6.3. Data Gathering and Analyses

Primary data from the field were specifically gathered from representatives of companies in the concrete supply chain for construction [66]. Secondary data were gathered from libraries and other searches [67,68]. These data were then used to undertake comparative analyses of glass suitability as concrete aggregate. Statistical Package for the Social Sciences (SPSS) Statistics Version 23.0 software was used to analyze and evaluate the quantitative data gathered from the questionnaire-based survey [59]. This analyzed data into graphs and charts that enabled comparisons to be made with the findings of similar previous research [59,69,70].

7. Data Analyses

7.1. Research Participants

Initially, 128 questionnaires were sent to companies in the concrete supply chain for construction; 21 of them failed to reply, and a total of 107 companies situated in Australia, Canada, New Zealand, the UK, and the USA were surveyed (see Figure 1). The participant companies were controlled methodically through randomized sampling. These companies were invited at random from the construction industry of these five countries [60]. The randomized sample in this quantitative study enabled the entire construction industry to be generalized with greater reliability in the findings [60,62,69]. The sampling of participant companies was also staged [69]. Strong interest in this research amongst companies within the concrete supply chain was evident as the survey had a high response rate of 84%.
Before testing for reliability, outliers were found. An interquartile range of beyond 2.2 is recommended [71]. In this study, outliers were identified beyond an interquartile range of 3.

7.2. Survey Questionnaire Reliability

SPSS Statistics Version 23.0 was used to perform factor analysis [72]. This is a technique used for data reduction, specifically, from many variables to those fewer underlying factors. These factors would summarize the key information that those variables contain. In this instance, factor analysis was used as a test to confirm the structure of this survey questionnaire. This was also a means of creating a reliable test, by determining which items were tapping into the same construct [73]. Some criteria had been used to reduce the variables. These were the categories of Amazing, Admirable, Adequate, Average, Low, and Unacceptable. Factor analysis had been undertaken to reduce the number of variables (or VAR#) by summarizing these into set components. This was carried out by locating groups that had strong inter-correlations in the set [74]. Establishing whether the data suited factor analysis involved performing the Kaiser–Meyer–Olkin (or KMO) and Bartlett’s Test of Sphericity. Principal component analysis was then used to extract the factors.
The values from the KMO test are between 0 and 1. Those nearest to 0 tend to provide larger correlations relative to all others in total. The values from this study and their interpretations are presented in Table 2 [75,76]. The Bartlett Test of Sphericity summarizes factors when different variables are redundant [77,78]. The Bartlett Test of Sphericity should achieve a significance of p < 0.05 for factor analysis to be deemed suitable [78,79]. Table 3 presents appropriate scores of 0.703 and p 0.00 for KMO and significance, respectively.
Relationships between variables were noticed for coefficients above 0.3 [80]. The loadings were categorized as follows [79]:
  • Minimal = Approximately 0.3;
  • Important = Approximately 0.4;
  • Significant = Approximately 0.5.
Sufficient values were found above 0.3 for the factor analysis to proceed. The data were extracted using the Kaiser criteria of eigenvalue > 1 as the collective variance percentage (or %) and Scree tests [79]. There is no definitive approach for keeping or extracting factors [74,79]. It is for this reason that selecting multiple approaches has been suggested for extraction [74]. The first four components were found to have eigenvalues > 1, with a cumulative variance of 77%. Scree tests were, therefore, undertaken as recommended [74,79]. Only those components beyond the red dashed line as the break had been retained [74]. We found that 53% of the variance was captured by Components 1 and 2 (see Figure 2).
SPSS Statistics Version 23.0 only extracts data from a maximum of two components and presents R values > 0.3 [72]. An unrotated component matrix of Components 1 and 2 is presented in Table 4. Those variables with R values > 0.4 have strong interrelationships.
Table 4 shows that factor extraction has not been optimized for Components 3 and 4, because they have <4 loaded items per component. The correlation of the component matrix in Table 5 shows a strong relationship with Components 1 and 2. Varimax rotation is suited to this component interrelationship [74,79].
Internal consistency is the number of items measuring similar variables within a survey instrument. Cronbach’s Alpha tested the internal reliability of the survey questionnaire that was used [81]. An alpha range of between 0.5 and 0.9 is deemed reliable [82]. Table 6 shows a 0.642 alpha score for the entire questionnaire itself and 0.693 for Component 1. They are therefore deemed reliable [81,82].

7.3. Descriptive Analysis

SPSS Statistics Version 23.0 was used for breaking down the data in Component 1 [72]. For the descriptive analyses for the first six variables, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8 are bar charts that provide the respondent frequencies to enable comparison.
SPSS Statistics Version 23.0 was used to analyze the means and standard deviations for each variable [72]. Descriptive results for each variable in Component 1 are displayed in Table 7.
Table 8 shows that the Cronbach’s Alpha value for the entire survey may be improved. This is achievable through the removal of variables VAR 2, #5, and #6. Their removal may improve the reliability of the entire survey fractionally, according to their shown Cronbach Coefficient if Item Removed [73]. In Table 8, VAR 1, #3, #4, and #6 display unique results. The range of VAR 2 is relatively small because of the five answer categories in its closed questions. The range of VAR 5 is greater than was expected.
SPSS Statistics Version 23.0 was also used for examining the percentiles, weighted rankings, and means. The data were ranked, and, in tied cases, adopted the mean rank of their values. The mean scores for the variables in Component 1 were then issued. To gain a further understanding of the descriptive data, normality was assessed with variable dispersion in SPSS Statistics by determining their skew and kurtosis [72]. Skew is the measure of a variable’s asymmetrical distribution. Kurtosis is the measure of distribution peak [83].
SPSS Statistics Version 23.0 was also used to perform the Kruskal–Wallis test (KWt) to determine any significant differences amongst the rankings of respondents [72]. KWt suited this study as it enabled more than two groups to be compared. This is because the data obtained have an even distribution and have been ranked. In evaluating them, VAR 2 was independent and contained five groups. VAR 3 and #4 showed statistical differences, each of them with p-values of <0.05 [84]. Conversely, VAR 1, #5, and #6 did not significantly differ as they had p values of >0.05. Yet, some statistical differences have still been shown as their Chi-Square values were relatively high [78,84].

7.4. Carbon Dioxide Emissions in Extraction

To address Objective Three of this study, Component 1 variables have been used in calculating the mean impact of the suited amounts of glass aggregate on the natural environment. This was undertaken based on the emissions data for extracting aggregates in the System Boundary Model [85]. Calculating for extraction involved using the emissions data [85], multiplied with the aggregate means. The answer represents an estimate of the quarry amount that recycled glass could replace:
=(50% × VAR 1) + (30% × VAR 3)
=(0.5 × 354) + (0.3 × 795)
=177 (fine aggregate) + 238.5 (coarse aggregate)
Take the sourced amounts for emissions from extracting fine aggregate [85]:
=23 kg (natural)—9 kg (recycled glass)
=14 kg of reduced carbon dioxide per ton of fine aggregate
Take the sourced amounts for emissions from extracting coarse aggregate [85]:
=32 kg (natural)—11 kg (recycled glass)
=21 kg of reduced carbon dioxide per ton of coarse aggregate
Then, in substituting these amounts:
=(14 kg × VAR 1) + (21 kg × VAR 3)
=(14 kg × 177) + (21 kg × 238.5)
=2478 kg (fine aggregate) + 5009 kg (coarse aggregate)
=7487 kg of reduced carbon dioxide emissions per day from an average quarry
In addition, around 33.81 g of carbon dioxide is emitted by a loaded truck per km of a typical journey [86]. From VAR 4, 26.24 tons of aggregate on average is being carried per truckload. In calculating the carbon footprint of glass versus natural aggregate, the following assumptions have been made. Extracting fine and coarse aggregates generates different amounts of carbon dioxide emissions. These estimates of emissions for extracting both aggregates as kg of carbon dioxide per ton and lifecycle assessment (LCA) analysis are provided. The energy expended is assumed to either be from electricity, diesel, or a combination of these both. Fine aggregate is assumed to be natural sand. Coarse aggregate is assumed to be crushed stone [85].
The environmental impact of natural aggregates is already well known. This includes that from LCA. In the LCA analysis of natural sand, the costs of its processing activities entail expending energy to extract this natural resource, and in diesel transportation for on-site handling, storage, vessel loading, hauling to another port, and then onto the use sites. In the LCA analysis of crushed stone, the costs of its processing activities entail expending energy extracting this natural resource, scalping, screening, crushing, and sieving, as well as in diesel transportation for on-site handling, vessel loading, hauling to another port, and then onto the use sites, whereas, in the LCA analysis of waste glass, the costs of its processing activities would generally entail recycling this material, expending energy milling and sieving, as well as in diesel transportation for its collection at a plant, on-site handling, and then onto the use sites [85].

8. Discussion of Glass Suitability

The statistical approach by analyzing the returned survey questionnaires and the information gathering from the existing research are two different research methodologies. Research Objective Three is to study and analyze the questionnaires based on the experience of companies from five countries. This desk-based study and statistical analyses have previously been presented in Section 7. The reason for the forthcoming discussion based on the literature in Section 8 is to achieve Research Objective Two.

8.1. Water-to-Cement Ratio

The water-to-cement ratio is defined as that “of the mass of total free water in a batch to the mass of concrete” [64] (p. 9). Table 9 provides the water-to-cement ratios adopted in the concrete tests of previous studies. The amounts of each can be controlled by determining the slump. National standards provide information on the ideal slump for concrete testing. For example, to comply, the mix must be within 10% of this specified water-to-cement ratio [64].
When concrete is designed, the strength in compression of a water-to-cement ratio is normally treated similarly when glass aggregates are incorporated. If mixes containing glass aggregate have a lower compressive strength, then adjustments are necessary to suit it. The strength in the compression of glass aggregate concrete with a lower water-to-cement ratio could be greater than their natural counterparts [87]. Concrete containing glass aggregate begins to reduce its strength in compression from a water-to-cement ratio of 0.6 [4]. Concrete-containing glass can increase its strength in compression by up to 5 MPa if the water-to-cement ratio is reduced from approximately 0.52 to 0.46 [46].
National standards also provide a reference for the testing of concrete in both compression and tension [64] (p. 35). Table 10 compares the strengths in tension and compression of controlled concrete specimens between the previous research at different grades. The amounts amongst these works of research contain normal aggregates, no glass. It is argued from this study that substituting between 20% and 100% of coarse aggregate with glass can improve these respective strengths of concrete.

8.2. Slump Workability and Density

At least eight previous studies have demonstrated that substituting aggregate with glass tended to reduce the workability of concrete by as much as 42%. National standards also set the parameters with which the concrete slump test must comply [64]. A slump can be maintained despite having a higher water-to-cement ratio [7]. Table 11 shows three previous studies to be inside the slump tolerances at a 30% glass substitution and six at 50%. Table 11 also presents two mechanical properties of concrete. These are specifically for compression and tension. Fresh state concrete is conventionally already understood to be very strong in both properties. These fundamental aspects of concrete are to be maintained when it comes to the applicability of substituting natural aggregate with glass. Intriguingly, the control samples for strength tests vary significantly amongst 16 previous studies, particularly following this substitution. The compression test results ranged between 3 and 10. Similarly, the tension test results ranged between 3 and 9. These variances are attributable to differences in the % of natural aggregate that has been substituted with glass. It is noteworthy that none of the slump values at a 100% substitution of natural aggregate with glass comply with the workability requirements [64].
The slump decreases have been excessive as their glass aggregate is much larger relative to the sand used. This is because a greater ratio of cement would be required for the adherence of glass than it would be for sand [11]. When cured, concrete ideally has a mass of 2100 to 2800 kg/m3 [64]. All seven previous studies that specified concrete densities ranged between 2223 and 2375 kg/m3. Hence, they comply with the concrete density requirements [64].

8.3. Air Content and Alkali–Silica Reaction

The air content of concrete is required to be no greater than 1.5% [64]. The concrete of the previous studies was indeed inside this 1.5% air content limit across all the glass substitution ratios, except for one study [11]. Their concrete surpassed the air content limit [64], which resulted from the following [11]:
  • A relatively high slump decrease;
  • The large glass aggregate relative to sand;
  • Relatively more surface areas that retain greater amounts of air.
The ASR inevitably occurs between the glass and cement, which will cause the concrete to expand in the long-term future. Table 12 and Table 13 show previous studies that researched fly ash in concrete. They collectively found that adding between 25% and 30% fly ash created a pozzolanic counter-reaction to this ASR, causing this to be inside the acceptable limits of the expansion set [65]. In addition, national standards also recommend that fly ash be used as an admixture in concrete [88].

9. Conclusions

In achieving Objective One, there is existing literature on how much carbon dioxide has been emitted in extracting both fine and coarse aggregates. Producing coarse aggregate in particular tends to consume between 30% and 40% greater energy than the extraction of sand [6,22,23,55]. The previous studies determined the amounts of carbon dioxide emitted from extracting aggregates [55,85]. Carbon dioxide emissions per ton tended to vary by up to 30% [55]. Using the System Boundary Model, 32 kg (net) and 11 kg (gross) of carbon dioxide tend to be emitted per ton of gravel produced. Only 23 kg (net) and 9 kg (gross) of carbon dioxide tend to be emitted per ton of sand extracted [85]. These amounts have also been used in addressing Objective Three of this study.
In achieving Objective Two, previous studies that researched glass aggregates in concrete were reviewed. Their water-to-cement ratios, strengths, slump workability, and density, as well as air content and ASR, were compared with their requirements in particular [64,65]. Using the cement additive of fly ash is effective in concrete containing glass aggregates as well. This study determined that it is indeed feasible to use glass in concrete structures that contain an aggregate ratio of no more than 50% fine by 30% coarse and cement with 25% fly ash. Thus, the viability of Objective Two of this study is confirmed.
In achieving Objective Three, widely distributed results from the research participants are displayed from the descriptive analyses. Calculating the effect of using waste glass on the natural environment, in a ratio of 50% fine to 30% coarse, we found that significant reductions in energy would otherwise be consumed from aggregate production. Specifically, this has the potential to result in reduced carbon dioxide emissions by as much as 7487 kg per day from an average quarry. Previous studies have indicated the energy consumption as being similar between natural aggregates and recycled glass [3,28]. Contrastingly, potential has been found for the recycling of glass to consume less energy. Hence, using glass in place of natural aggregates could save a substantial amount of energy, thus, addressing the aim of the study presented in this paper.

Author Contributions

Conceptualization, C.E.-F.; Methodology, C.E.-F. and R.L.; Software, C.E.-F. and R.L.; Validation, C.E.-F. and R.L.; Formal analysis, C.E.-F.; Investigation, C.E.-F.; Resources, C.E.-F. and R.L.; Data curation, C.E.-F. and R.L.; Writing—original draft, R.L.; Writing—review & editing, R.L.; Visualization, C.E.-F. and R.L.; Supervision, R.L.; Project Administration, C.E.-F. and R.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was approved by the Human Research Ethics Committee (HREC) of Curtin University (HRE2017-0510 on 8 August 2017).

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest. Author Charbel El-Fata was employed by the company KBR Incorporated. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Wilkowsky, D.I. Waste Glass as an Aggregate in Concrete. Master’s Thesis, School of Engineering, University of Southern California, Los Angeles, CA, USA, 1973. [Google Scholar]
  2. Mehta, K.P. Reducing the environmental impact of concrete. In Concrete Can Be Durable and Environmentally Friendly; Semioli, B., Hills, F., Eds.; Concrete International: Farmington Hills, MI, USA, 2001; Volume 23, pp. 61–66. [Google Scholar]
  3. Marinkovic, S.; Radonjanin, V.; Malešev, M.; Ignjatović, I. Comparative environmental assessment of natural and recycled aggregate concrete. Waste Manag. 2010, 30, 2255–2264. [Google Scholar] [CrossRef]
  4. Koh, J.; Sarsby, R.W.; BenSaid, A.A.M. Use of waste glass as fine aggregate in structural concrete. In Construction for a Sustainable Environment, 1st ed.; Meggyes, R., Koh, J., Sarsby, R.W., Eds.; Taylor and Francis: London, UK, 2010; pp. 366–371. [Google Scholar]
  5. Romero, D.F. Concrete Durability and Environmental Performance of Mixtures Containing Recycled Hazardous Waste Aggregates. Ph.D. Thesis, University of Miami, Coral Gables, FL, USA, 2013. [Google Scholar]
  6. Rossi, E.; Sales, A. Carbon footprint of coarse aggregate in Brazilian construction. Constr. Build. Mater. 2014, 72, 333–339. [Google Scholar] [CrossRef]
  7. DeCastro, S.; DeBrito, J. Evaluation of the durability of concrete made with crushed glass aggregates. J. Clean. Prod. 2012, 47, 7–14. [Google Scholar] [CrossRef]
  8. Danielsen, S.W.; Kuznetsova, E. Environmental Impact and Sustainability in Aggregate Production and Use. In Engineering Geology for Society and Territory; Lollino, G., Manconi, A., Guzzetti, F., Culshaw, M., Bobrowsky, P., Luino, F., Eds.; Springer International Publishing: Geneva, Switzerland, 2015; Volume 5, pp. 41–44. [Google Scholar] [CrossRef]
  9. Lollino, G.; Manconi, A.; Guzzetti, F.; Culshaw, M.; Bobrowsky, P.; Luino, F. Engineering Geology for Society and Territory—Urban Geology, Sustainable Planning and Landscape Exploitation; Springer: New York, NY, USA, 2015; Volume 5, 1400p. [Google Scholar] [CrossRef]
  10. Topcu, I.B.; Canbaz, M. Properties of concrete containing waste glass. Cem. Concr. Res. 2002, 34, 267–274. [Google Scholar] [CrossRef]
  11. Park, S.B.; Lee, B.C.; Kim, J.H. Studies on mechanical properties of concrete containing waste glass aggregate. Cem. Concr. Res. 2004, 34, 2181–2189. [Google Scholar] [CrossRef]
  12. Kou, S. Reusing Recycled Aggregates in Structural Concrete. Ph.D. Thesis, Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, 2006. [Google Scholar]
  13. Berry, M.; Stephens, J.; Cross, D. Performance of 100% fly ash concrete with recycled glass aggregate. ACI Mater. J. 2011, 108, 378–384. [Google Scholar] [CrossRef]
  14. Du, H.; Tan, K.H. Concrete with recycled glass as fine aggregates. ACI Mater. J. 2014, 111, 47–58. [Google Scholar]
  15. Statistics Canada. Annual Statistics; Statistics Canada—Environment Accounts and Statistics Division: Ottawa, ON, Canada, 2005. [Google Scholar]
  16. Australian Greenhouse Office. Energy Efficiency in Government Operations (EEGO) Policy, 2nd ed.; Commonwealth of Australia—Department of the Environment and Water Resources: Canberra, ACT, Australia, 2007; pp. 1–29. [Google Scholar]
  17. Ministry for the Environment. Environmental Report Card—July; New Zealand Government: Wellington, New Zealand, 2009. [Google Scholar]
  18. EPA. Solid Waste and Emergency Response; Environmental Protection Agency: Washington, DC, USA, 2015. [Google Scholar]
  19. Department for Environment, Food and Rural Affairs—UK Statistics on Waste. Available online: https://www.gov.uk/government/statistics/uk-waste-data/uk-statistics-on-waste (accessed on 22 November 2024).
  20. Municipal Waste—OECD (Organisation for Economic Cooperation and Development). Available online: https://www.oecd.org/en/data/indicators/municipal-waste.html (accessed on 22 November 2024).
  21. American Concrete Institute. Vision 2030—A Vision for the US Concrete Industry; Strategic Development Council: Washington DC, USA, 2001; p. i–A-4. [Google Scholar]
  22. Flower, D.J.M.; Sanjayan, J.G. Greenhouse gas emissions due to concrete manufacture. Int. J. Life Cycle Assess. 2007, 12, 282–288. [Google Scholar] [CrossRef]
  23. VanDenHeede, P.; DeBelie, N. Environmental impact and life cycle assessment (LCA) of traditional and ‘green’ concretes—Literature review and theoretical calculations. Cem. Concr. Compos. 2012, 34, 431–442. [Google Scholar] [CrossRef]
  24. Ghamari, A.; Powezka, A.; Kytinou, V.K.; Amini, A. An innovative fire-resistant lightweight concrete infill wall reinforced with waste glass. Buildings 2024, 14, 626. [Google Scholar] [CrossRef]
  25. Surendran, H.; Akhas, P.K. Unraveling the strength and enhanced durability of concrete using toughened waste glass aggregate. ASCE J. Mater. Civ. Eng. 2024, 36, 04023634. [Google Scholar] [CrossRef]
  26. Dacombe, P.J.; Krivstov, V.; Banks, C.J.; Heaven, S. Use of energy footprint analysis to determine the best options for management of glass from household waste. In Sustainable Waste Management and Recycling—Glass Waste; Limbachiya, M.C., Roberts, J.J., Eds.; Thomas Telford Publishing: London, UK, 2004; pp. 265–272. [Google Scholar]
  27. James, K. Methodology for Assessing the Climate Change Impacts of Packaging Optimisation Under the Courtauld Commitment Phase 2; Waste and Resources Action Programme (WRAP)—Material Change for a Better Environment: Banbury, UK, 2010; pp. 1–39. [Google Scholar]
  28. Blengini, G.A.; Busto, M.; Fantoni, M.; Fino, D. Eco-efficient waste glass recycling—Integrated waste management and green product development through LCA. Waste Manag. 2012, 32, 1000–1008. [Google Scholar] [CrossRef]
  29. CCAA. Use of Recycled Aggregates in Construction—Report; Cement Concrete and Aggregates (CCA): West Perth, WA, Australia, 2008; pp. 1–25. [Google Scholar]
  30. Hama, S.M.; Mahmoud, A.S.; Yassen, M.M. Flexural behavior of reinforced concrete beam incorporating waste glass powder. Structures 2019, 20, 510–518. [Google Scholar] [CrossRef]
  31. Bostanci, S.C. Use of waste marble dust and recycled glass for sustainable concrete production. J. Clean. Prod. 2020, 251, 119785. [Google Scholar] [CrossRef]
  32. Jain, K.L.; Sancheti, G.; Gupta, L.K. Durability performance of waste granite and glass powder added concrete. Constr. Build. Mater. 2020, 252, 119075. [Google Scholar] [CrossRef]
  33. Tamanna, N.; Tuladhar, R.; Sivakugan, N. Performance of recycled waste glass sand as partial replacement of sand in concrete. Constr. Build. Mater. 2020, 239, 117804. [Google Scholar] [CrossRef]
  34. Dong, W.; Li, W.; Tao, Z. A comprehensive review on performance of cementitious and geopolymeric concretes with recycled waste glass as powder, sand or cullet. Resour. Conserv. Recycl. 2021, 172, 105664. [Google Scholar] [CrossRef]
  35. Esmaeili, J.; AL-Mwanes, A.O. A review—Properties of eco-friendly ultra-high-performance concrete incorporated with waste glass as a partial replacement for cement. Mater. TodayProc. 2021, 42, 1958–1965. [Google Scholar] [CrossRef]
  36. Ibrahim, K.I.M. Case study—Recycled waste glass powder as a partial replacement of cement in concrete containing silica fume and fly ash. Case Stud. Constr. Mater. 2021, 15, e00630. [Google Scholar] [CrossRef]
  37. Yoo, D.Y.; You, I.; Zi, G. Effects of waste liquid—Crystal display glass powder and fiber geometry on the mechanical properties of ultra-high-performance concrete. Constr. Build. Mater. 2021, 266, 120938. [Google Scholar] [CrossRef]
  38. Andic-Caki, O.; Uzum, O.; Yuksel, C.; Sarikanat, M. Waste glass aggregate for cementitious and polymer concrete. Constr. Mater. 2016, 169, 106–116. [Google Scholar] [CrossRef]
  39. Randell, P.; Pickin, J.; Grant, B. Waste Generation and Resource Recovery in Australia; Australian Government—Department of Sustainability, Environment, Water, Population, Communities and Blue Environment Pty Ltd.: Melbourne, VIC, Australia, 2014. [Google Scholar]
  40. WRAP. Recycled Glass Market Study and Standards Review—Update; The Waste and Resources Action Programme (WRAP): Oxford, UK, 2004. [Google Scholar]
  41. Gautam, S.P.; Srivastava, V.; Agarwal, V.C. Use of glass wastes as fine aggregate in concrete. J. Acad. Ind. Res. 2012, 1, 320–322. [Google Scholar]
  42. Ali, E.E.; AlTersawi, S.H. Recycled glass as a partial replacement for fine aggregate in self-compacting concrete. Constr. Build. Mater. 2012, 35, 785–791. [Google Scholar] [CrossRef]
  43. Sidharthan, O.; Vijayaraghavan, C.; Siveraman, S. A study on compressive strength of concrete using crushed glass as fine aggregate. Int. J. Res. Eng. Sci. Technol. 2016, 2, 73–77. [Google Scholar]
  44. Tuncan, M.; Karasu, B.; Yalcin, M. The Suitability of Using Glass and Fly Ash in Portland Cement Concrete. In Proceedings of the 11th International Offshore and Polar Engineering (ISOPE) Conference, Stavanger, Norway, 17–22 June 2001; Volume 4, p. ISOPE-I-01-361. [Google Scholar]
  45. Zammit, L.; Montesin, F.E.; Torpiano, A. The Use of Crushed Glass Waste as Fines in Concrete Construction. In Sustainable Waste Management and Recycling: Glass Waste: Proceedings of the International Conference Organised by the Concrete and Masonry Research Group and Held at Kingston University-London on 14–15 September 2004; Thomas Telford: London, UK, 2004. [Google Scholar]
  46. Shayan, A.; Xu, A. Value-added utilisation of waste glass in concrete. Cem. Concr. Res. 2004, 34, 81–89. [Google Scholar] [CrossRef]
  47. Sagoe-Crentsil, K.; Brown, T.; Taylor, A.H. Performance of Recycled Aggregate Concrete—Aggregate Quality and Durability Requirements. In Biennial Conferences; Concrete Institute of Australia: Sydney, NSW, Australia, 2011. [Google Scholar]
  48. Shi, C.; Zheng, K. A review on the use of waste glasses in the production of cement and concrete. Resour. Conserv. Recycl. 2007, 52, 234–247. [Google Scholar] [CrossRef]
  49. Liang, H.; Zhu, H.; Byars, E.A. Use of Waste Glass as Aggregate in Concrete. In Proceedings of the 7th UK Chinese Association of Resources and Environment—Annual General Meeting (CARE–AGM); The University of Greenwich: Greenwich, UK, 2007; Volume 15. [Google Scholar]
  50. Afshinnia, K.; Rabgaraju, P.R. Impact of combined use of ground glass powder and crushed glass aggregate on selected properties of Portland cement concrete. Constr. Build. Mater. 2016, 117, 263–272. [Google Scholar] [CrossRef]
  51. Shao, Y.; Lefort, T.; Moras, S.; Rodriguez, D. Studies on concrete containing ground waste glass. Cem. Concr. Res. 1998, 30, 91–100. [Google Scholar] [CrossRef]
  52. Almesfer, N.; Ingham, J. Effect of waste glass on the properties of concrete. J. Mater. Civ. Eng. 2014, 26, 06014022. [Google Scholar] [CrossRef]
  53. Ling, T.C.; Poon, C.S. Feasible use of recycled CRT funnel glass as heavyweight fine aggregate in barite concrete. J. Clean. Prod. 2012, 32, 42–49. [Google Scholar] [CrossRef]
  54. Budney, H.D. Refining the Process—Evaluating the Environmental Assessment of Mineral Aggregate Resources (Sand, Gravel and Crushed Stone). Master’s Thesis, School of Resource and Environmental Management, University of Alberta, Edmonton, AB, Canada, 2007. [Google Scholar]
  55. Flower, D.J.M.; Sanjayan, J.G.; Baweja, D. Environmental Impacts of Concrete Production and Construction. In Proceedings of the 22nd Biennial Conference of the Concrete Institute of Australia, Melbourne, VIC, Australia, 17–19 October 2005; pp. 1–10. [Google Scholar]
  56. Friedrich, E.; Trois, C. GHG emission factors developed for the collection, transport and landfilling of municipal waste in South Africa. Waste Manag. 2013, 33, 1013–1026. [Google Scholar] [CrossRef] [PubMed]
  57. University of Cape Town. Ecology, Environment and Conservation; Conservation Research: Atlanta, GA, USA, 2014. [Google Scholar]
  58. Krivstov, V.; Wager, P.A.; Dacombe, P.; Gilgen, P.W.; Heaven, S.; Hilty, L.M.; Banks, C.J. Analysis of energy footprints associated with recycling of glass and plastic—Case studies for industrial ecology. Ecol. Model. 2004, 174, 175–189. [Google Scholar] [CrossRef]
  59. Dudovskiy, J. The Ultimate Guide to Writing a Dissertation in Business Studies—A Step-by-Step Assistance, 7th ed.; Business Research Methodology (BRM): Pittsburgh, PN, USA, 2024; Available online: https://research-methodology.net/about-us/ebook/ (accessed on 11 November 2024).
  60. Rudestam, K.E.; Newton, R.R. Surviving Your Dissertation—A Comprehensive Guide to Content and Process, Methods of Inquiry; SAGE Publications Incorporated: Thousand Oaks, CA, USA, 2014. [Google Scholar]
  61. Babbie, E.R. Survey Research Methods, 2nd ed.; Wadsworth Cengage Learning: Belmont, CA, USA, 1999. [Google Scholar]
  62. Creswell, J.W.; Creswell, J.D. Research Design—Qualitative, Quantitative and Mixed Methods Approaches; SAGE Publications Incorporated: London, UK, 2017. [Google Scholar]
  63. Nesbary, D.K. Survey Research and the World Wide Web; Pearson Education—Allyn and Bacon Incorporated: Boston, MA, USA, 2000. [Google Scholar]
  64. AS 1379; Specification and Supply of Concrete. Part 1—Concrete Aggregates. Council of Standards Australia: Sydney, NSW, Australia, 2007.
  65. ASTM C1260; Standard Test Method for Potential Alkali Reactivity of Aggregates—Mortar Bar Method. ASTM International: West Conshohocken, PA, USA, 2007.
  66. Survey Monkey. Available online: https://www.surveymonkey.com/ (accessed on 11 November 2024).
  67. Google Scholar. Available online: https://scholar.google.com/ (accessed on 22 November 2024).
  68. Cement Concrete and Aggregates Australia (CCAA). Available online: http://www.ccaa.com.au/ (accessed on 23 January 2017).
  69. Creswell, J.W. Educational Research—Planning, Conducting and Evaluating Quantitative and Qualitative Research, 6th ed.; Pearson: New York, NY, USA, 2019. [Google Scholar]
  70. Avgousti, K. Research philosophy, methodology, quantitative and qualitative methods. Cyprus J. Sci. 2013, 11, 33–43. [Google Scholar]
  71. Hoaglin, D.C.; Iglewicz, B. Fine tuning some resistant rules for outlier labeling. J. Am. Stat. Assoc. 1987, 82, 1147–1149. [Google Scholar] [CrossRef]
  72. IBM SPSS Statistics. Available online: https://www.ibm.com/au-en/products/spss-statistics (accessed on 11 November 2024).
  73. Coakes, S.J.; Steed, L.; Ong, C. SPSS Version 17.0 for Windows—Analysis Without Anguish; John Wiley and Sons: Milton, NSW, Australia, 2010; 289p. [Google Scholar]
  74. Yong, A.G.; Pearce, S. A beginner’s guide to factor analysis—Focusing on exploratory factor analysis. Tutor. Quant. Methods Psychol. 2013, 9, 79–94. [Google Scholar] [CrossRef]
  75. Kaiser, H.F. An index of factor simplicity. Phychometrika 1974, 39, 31–36. [Google Scholar] [CrossRef]
  76. Cerny, C.A.; Kaiser, H.F. A study of a measure of sampling adequacy for factor-analytic correlation matrices. Multivar. Behav. Res. 1977, 12, 43–47. [Google Scholar] [CrossRef]
  77. Snedecor, G.W.; Cochran, W.G. Statistical Methods, 8th ed.; Wiley—Blackwell: Iowa, IA, USA, 1991. [Google Scholar]
  78. Sigmund, T.; Carlson, J.E. Brief report—Bartlett’s test of sphericity and chance findings in factor analysis. Multivar. Behav. Res. 2010, 4, 375–377. [Google Scholar] [CrossRef]
  79. Williams, B.; Onsman, A.; Brown, T. Exploratory factor analysis—A five-step guide for novices. J. Emerg. Prim. Health Care 2010, 9, 1–13. [Google Scholar] [CrossRef]
  80. Awang, Z. A Handbook on Structural Equation Modeling (SEM); Universiti Sultan Zainal Abidin—MPWS Rich Resources: Kuala Lumpur, Malaysia, 2014. [Google Scholar]
  81. Tavakol, M.; Dennick, R. Making sense of Cronbach’s alpha. Int. J. Med. Educ. 2011, 2, 53–55. [Google Scholar] [CrossRef]
  82. Gliem, J.A.; Gliem, R.R. Calculating, Interpreting and Reporting Cronbach’s Alpha Reliability Coefficient for Likert-Type Scales. In Proceedings of the Midwest Research-to-Practice Conference in Adult, Continuing and Community Education, Columbus, OH, USA, 8–10 October 2003; Volume 1, pp. 82–87. [Google Scholar]
  83. Kim, H.Y. Statistical notes for clinical researchers—Assessing normal distribution (2) using skewness and kurtosis. Restor. Dent. Endod. 2013, 38, 52–54. [Google Scholar] [CrossRef]
  84. Vargha, A.; Delaney, H.D. The Kruskal Wallis test and stochastic homogeneity. J. Educ. Behav. Stat. 1998, 23, 170–192. [Google Scholar] [CrossRef]
  85. Hossain, U.; Poon, C.S.; Lo, I.M.C.; Cheng, J.C.P. Comparative environmental evaluation of aggregate production from recycled waste materials and virgin sources by LCA. Resour. Conserv. Recycl. 2016, 109, 66–77. [Google Scholar] [CrossRef]
  86. Thomas, A.; Lombardi, D.R.; Hunt, D.; Gaterell, M. Estimating carbon dioxide emissions for aggregate use. Eng. Sustain. 2009, 162, 135–144. [Google Scholar] [CrossRef]
  87. Zou, P.X.W.; Zhang, G.; Wang, J.Y. Identifying Key Risks in Construction Projects—Life Cycle and Stakeholder Perspectives. In Proceedings of the Pacific Rim Real Estate Society Conference, Auckland, New Zealand, 22–25 January 2006. [Google Scholar]
  88. AS 2578.1; Aggregates and Rock for Engineering Purposes. Part 1—Concrete Aggregates. Council of Standards Australia: Sydney, NSW, Australia, 2014.
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Figure 1. Survey respondent locations.
Figure 1. Survey respondent locations.
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Figure 2. Scree and Cut Off Point plot with factor numbers and eigenvalues.
Figure 2. Scree and Cut Off Point plot with factor numbers and eigenvalues.
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Figure 3. Production of fine aggregate and respondent numbers bar chart.
Figure 3. Production of fine aggregate and respondent numbers bar chart.
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Figure 4. Aggregate sources and respondent numbers bar chart.
Figure 4. Aggregate sources and respondent numbers bar chart.
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Figure 5. Production of coarse aggregate and respondent numbers bar chart.
Figure 5. Production of coarse aggregate and respondent numbers bar chart.
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Figure 6. Loads of haulage (tons) and respondent numbers bar chart.
Figure 6. Loads of haulage (tons) and respondent numbers bar chart.
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Figure 7. Aggregate distribution (%) and respondent numbers bar chart.
Figure 7. Aggregate distribution (%) and respondent numbers bar chart.
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Figure 8. Distances of haulage (km) and respondent numbers bar chart.
Figure 8. Distances of haulage (km) and respondent numbers bar chart.
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Table 1. Waste glass generated in millions of tons [15,17,18,19,20].
Table 1. Waste glass generated in millions of tons [15,17,18,19,20].
CountryTotal Generated Glass WasteRecycled AmountWastePercent (%) Recycled
Australia (2002)1.040.510.5349%
Canada (2005)0.360.080.2822%
NZ (2005)0.130.070.0643%
UK (2015)2.401.610.7967%
USA (2014)11.543.158.3934%
Table 2. Kaiser–Meyer–Olkin values and interpretations.
Table 2. Kaiser–Meyer–Olkin values and interpretations.
InterpretationFromTo
Amazing0.901.00
Admirable0.800.89
Adequate0.700.79
Average0.600.69
Low0.500.59
Unacceptable0.000.49
Table 3. Results of Kaiser–Meyer–Olkin and Bartlett tests.
Table 3. Results of Kaiser–Meyer–Olkin and Bartlett tests.
KMO Measure of Sample Adequacy0.703
Bartlett Test of SphericityApproximate Chi-Square342.474
df45.000
Significance0.000
Table 4. Factor matrix for Components 1 and 2.
Table 4. Factor matrix for Components 1 and 2.
CodeVariablesComponent
12
VAR 1Production of Fine Aggregate0.921
VAR 2Aggregate Source0.898
VAR 3Production of Coarse Aggregate0.877
VAR 4Load of Haulage (T)0.776
VAR 5Aggregate Distribution (%)−0.614
VAR 6Distance of Haulage (km)0.4450.303
VAR 7Glass Knowledge −0.841
VAR 8Aggregate Type 0.648
VAR 9Environmental Focus 0.566
VAR 10Environmental Policy
Extraction method—Principal component analysis. Two components extracted.
Table 5. Component factor matrix and varimax rotation.
Table 5. Component factor matrix and varimax rotation.
CodeVariablesComponent
1234
VAR 1Production of Fine Aggregate0.933
VAR 2Aggregate Source0.917
VAR 3Production of Coarse Aggregate0.879
VAR 4Load of Haulage (T)0.768
VAR 5Aggregate Distribution (%)−0.573−0.355 0.505
VAR 6Distance of Haulage (km)0.3770.368
VAR 9Environmental Focus 0.895
VAR 10Environmental Policy 0.905
VAR 7Knowledge of Glass −0.544−0.575−0.413
VAR 8Aggregate Type 0.899
Extraction method—Principal component analysis. Rotation method—Varimax with Kaiser normalization. Rotation converged in six iterations.
Table 6. Component correlation factor matrix.
Table 6. Component correlation factor matrix.
Component12
10.9750.222
2−0.2220.975
Extraction method—Principal component analysis. Rotation method—Varimax with Kaiser normalization.
Table 7. Survey questionnaire reliability scores.
Table 7. Survey questionnaire reliability scores.
Cronbach’s AlphaNumber of Items
Entire Survey0.64210
Component 10.6936
Component 20.0034
Table 8. Descriptive results and reliability of Component 1.
Table 8. Descriptive results and reliability of Component 1.
CodeVariablesMeanStandard Error of the MeanStandard DeviationCronbach Coefficient if Item Removed
VAR 1Production of Fine Aggregate353.760100.4251024.1380.379
VAR 2Aggregate Source1.2200.0650.6770.649
VAR 3Production of Coarse Aggregate795.610134.1401367.9660.405
VAR 4Load of Haulage (T)26.2401.17211.5400.542
VAR 5Aggregate Distribution (%)57.7900.7156.2340.651
VAR 6Distance of Haulage (km)39.0705.34853.7500.644
Table 9. Minimums, maximums, and ranges of Component 1.
Table 9. Minimums, maximums, and ranges of Component 1.
CodeVariablesMinimumMaximumRange
VAR 1Production of Fine Aggregate010,00010,000
VAR 2Aggregate Source154
VAR 3Production of Coarse Aggregate710,0009993
VAR 4Load of Haulage (T)1080,00079,990
VAR 5Aggregate Distribution (%)307040
VAR 6Distance of Haulage (km)030003000
Table 10. Water-to-cement ratios and aggregate sizes.
Table 10. Water-to-cement ratios and aggregate sizes.
StudyWater/Cement RatioAggregate Size
[45]Not ProvidedFine
[51]0.75Fine
[44]Not ProvidedFine
[10]0.54Coarse
[11]0.50Fine
[46]0.456 to 0.52Fine and Coarse
[12]0.55Fine and Coarse
[49]Not ProvidedFine
[48]Not ProvidedFine and Coarse
[4]0.50 to 0.60Fine
[13]0.20Fine and Coarse
[7]0.55 to 0.58Fine and Coarse
[41]0.50Fine and Coarse
[52]0.60Fine and Coarse
[14]0.38Fine and Coarse
[50]0.45Coarse
[38]0.50Fine
[43]0.45Fine
Table 11. Control samples for strength tests and concrete grades.
Table 11. Control samples for strength tests and concrete grades.
StudyControl SamplesConcrete Grade
CompressionTension
[45]6 25
[51]6 20
[44]6660
[10]3320
[11] 420
[46]3 40
[12]6640
[49]4440
[4]3 30
[13] 3
[7]10 20
[41]6 30
[52]9925
[14]9930
[50]6640
[43]5 30
Table 12. Slump testing values from previous studies.
Table 12. Slump testing values from previous studies.
StudySlump ValueTolerance AllowedPercent (%) Glass Aggregate
20%30%50%70%100%
[45]55±10 60654540
[10]95±20 8090
[11]130±30 958571
[12]150±30160 170 190
[4]95±2085 78 60
[14]120±3095 90 100
[50]40±1035 20
Table 13. Fly ash used in previous studies.
Table 13. Fly ash used in previous studies.
StudyPercent (%) Fly Ash
[51]0% to 30%
[10]30%
[46]25%
[12]0% to 25%
[49]20%
[13]25%
[50]30%
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Lopez, R.; El-Fata, C. Environmental Implications of Using Waste Glass as Aggregate in Concrete. J. Compos. Sci. 2024, 8, 507. https://doi.org/10.3390/jcs8120507

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Lopez R, El-Fata C. Environmental Implications of Using Waste Glass as Aggregate in Concrete. Journal of Composites Science. 2024; 8(12):507. https://doi.org/10.3390/jcs8120507

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Lopez, Robert, and Charbel El-Fata. 2024. "Environmental Implications of Using Waste Glass as Aggregate in Concrete" Journal of Composites Science 8, no. 12: 507. https://doi.org/10.3390/jcs8120507

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Lopez, R., & El-Fata, C. (2024). Environmental Implications of Using Waste Glass as Aggregate in Concrete. Journal of Composites Science, 8(12), 507. https://doi.org/10.3390/jcs8120507

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