1 Introduction
2 Experimental Procedures
2.1 Materials
Composition (%) | SiO2 | Al2O3 | Fe2O3 | MgO | CaO | CaCO3 | K2O | Na2O |
---|---|---|---|---|---|---|---|---|
Cement | 21.16 | 3.96 | 5.69 | 2.13 | 63.34 | – | 0.49 | 0.16 |
NA | 97.05 | 0.24 | 0.64 | 0.15 | 0.56 | 0.46 | 0.49 | 0.41 |
GA | 78.33 | 1.85 | 0.25 | 0.06 | 9.65 | 0.93 | 0.53 | 8.4 |
2.2 Mix Design and Preparation of Mortar Specimens
Mix ID | Portland cement (g) | Glass powder (g) | Natural sand (g) | Glass sand (g) | Water (g) | Super-plasticizer (%) |
---|---|---|---|---|---|---|
GA0 | 500 | – | 1375 | – | 242.5 | – |
GA25 | 500 | – | 1031 | 344 | 242.5 | 0.25 |
GA50 | 500 | – | 687.5 | 687.5 | 242.5 | 0.3 |
GA75 | 500 | – | 344 | 1031 | 242.5 | 0.5 |
GA100 | 500 | – | – | 1375 | 242.5 | 0.7 |
GA75–GP5 | 475 | 25 | 344 | 1031 | 242.5 | 0.5 |
GA75–GP10 | 450 | 50 | 344 | 1031 | 242.5 | 0.5 |
GA75–GP15 | 425 | 75 | 344 | 1031 | 242.5 | 0.5 |
GA75–GP20 | 400 | 100 | 344 | 1031 | 242.5 | 0.5 |
GA75–GP25 | 375 | 125 | 344 | 1031 | 242.5 | 0.5 |
GA75–GP30 | 350 | 150 | 344 | 1031 | 242.5 | 0.5 |
Cement | GP | NA | Water | GA | SP | |
---|---|---|---|---|---|---|
GHGs (kg CO2/kg) | 0.82 | 0.338 | 0.024 | 0.0013 | 0.008 | 0.6 |
2.2.1 The Optimal GA Mortar
2.3 Testing Methods
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Mechanical strengths: flexural, compressive strengths and ultrasonic pulse velocity (UPV) were measured according to (ASTMC-348 standard, 2002; (ASTM C349-08, 2014) and (ASTM C 597-02, 2016), using specimen’s dimensions of (4 × 4 × 16) cm3 and (4 × 4 × 4) cm3, respectively. Both mechanical strengths were measured at different curing ages of 7, 28 and 90 days. Three specimens were tested for flexural strengths and UPV, whereas the average value of 6 cubs was considered for compressive strengths.
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The properties of the interfacial transition zone (ITZ) of NA/binder and GA/binder were observed after 28 days using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS).
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Alkali-silica reaction: The influence of GP on the alkali-silica reaction (ASR) of mortars prepared with optimum GA content was investigated at various GP dosages from 5 to 30%. For this reason, mortar bars of 2.5 × 2.5 × 28.5 cm3 were prepared, cured and tested according to (ASTM C1260 standard, 2007). After demoulding, the mortar bars were placed in hot water at a temperature of 80 ± 2 °C for 24 h. The reference length measurements were then taken before immersing the mortar bars in a 1N NaOH solution at a temperature of 80 ± 2 °C. Subsequent changes in length were measured after 3, 6, 9, 12 and 14 days of ASR test using a digital comparator with a precision of 0.001 mm. Each displayed result of length change was the average value of three tested specimens.
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The water permeability of mortars was estimated by their ability to be penetrated by water under a pressure gradient. Using a 3-cell device, measurements were made on cylindrical specimens of 100 mm diameter and 50 mm height, at the age of 90 days. The mortar specimens were covered laterally with a double layer of resin 24 h before the start of the test in order to avoid lateral leaks. Using a three-cell permeameter, the mortar discs were placed on a device under permanent water flow at a pressure of 0.3 MPa for 6 h (Kameche et al., 2014), the cumulative amount of water flowing through the mortar specimens as a function of time was measured every hour by decreasing the level in the manometer tube of the device. The coefficient of permeability was calculated by applying Darcy's law:$${K}_{{\text{l}}}=\frac{{Q}_{l}}{A.i},$$(1)where Q: volume of water per unit time (flow velocity). A: section crossed by water. KL: permeability coefficient. i: hydraulic gradient across the specimen (m/m).
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Rapid chloride permeability test (RCPT): the test of resistance to chloride ions was done according to (ASTM C, 1202, 2012). Cylindrical specimens of 100 mm in diameter and 50 mm in height prepared for each mixture are shown in Table 3. The outer perimeter of the specimen was covered with epoxy resin to ensure a good seal. After curing, the specimens were placed in a desiccator to evacuate the air existing in the mortar using a vacuum pump for 3 h. Then the specimens were stored in water for 18 ± 2 h. One side of the specimens was exposed to a 3% NaCl solution, and the second side was exposed to 0.3N NaOH solution. The current between the electrodes was measured every 30 min for 6 h. The total charge passed through the specimens was calculated using the following equation:
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The thermal conductivity (W/m.K) of mortars was measured using the thermal needle probe method according to (ASTM D5334, 2017), on 90-day-old cylindrical specimens of 100 mm diameter and 5 mm height. Thermal conductivity was determined by the KD2-PRO analyser using SH-1. The SH-1 contains two needles (1.27 mm diameter and 30 length) capable of measuring the thermal conductivity in the range of 0.2 W/m.K to 2 W/m.K. The measurements were repeated five times for each side of the specimen (Bostanci et al., 2020), the arithmetic averages of these measurements were reported as K-values.
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Resistance to sulphate attack: Penetration of MgSO4 through the pores leads to the formation of magnesium silicate hydrate (M–S–H), and displaced calcium precipitates, mainly in the form of gypsum and causing ettringite. Three (4 × 4 × 16) cm3 specimens of each mixture were placed in a 5% MgSO4 solution tray following (ASTM C1012-04, 2004). The mass change for each sample was measured weekly after 12 weeks. The mass loss in % was calculated relative to the initial mass.
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Resistance to sulphuric acid: External chemical attacks are mainly due to acids, bases and saline solutions which dissolve the lime in cement and form new compounds, leading to the swelling and bursting of concrete structures, which can jeopardize their stability. According to Zivica and Bajza (2001), special precautions must be taken when working in submerged areas. To test the behaviour of new mortars in the face of this type of attack. Three 4 × 4 × 16 cm3 specimens from each mixture were placed in a 5% H2SO4 solution in accordance with (ASTM C267, 2012). The average weight value of each sample was measured after 12 weeks while refreshing the solution after every measurement. The initial mass before immersion was utilized as a reference for different mass losses.
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To determine the environmental impact of GA and GP modified mortar samples, cradle-to-gate greenhouse gas (GHGs) emissions were measured for each material included in the mortar using the following equation (Ho and Huynh, 2022; Ameri et al., 2020):where \({h}_{i}\) represents the CO2 emission for each 1 kg for each material. \({m}_{i}\) represents the mass of material in each 1 m3 of mortar.$$\sum\nolimits_{{i = 1}}^{n} {h_{i} \, \times m_{i} ,}$$(3)In this study, HF acid are considered as a residual waste (Kusumawardaniet al., 2023; Toublanc, 2010), Consequently, the influence of HF acid and material transport on greenhouse gas emissions is neglected. GA and GP are produced from waste glass, which requires additional grinding to obtain smaller, finer aggregates.Grinding GA requires electricity energy estimated at 0.0309 kW h in order to obtain recycled aggregate used as a building material (Crawford et al., 2019), while obtaining GP smaller than 100 µm has been estimated at 0.25 kW h (Pan et al., 2017). Greenhouse gas emissions per unit mass (1 kg) used in the calculations related to mortars were taken from the greenhouse gas emissions database of each material included: cement–GP (Pan et al., 2017), GA–NA–water (Crawford et al., 2019) and SP (Yu et al., 2017), as shown in Table 3.