Impact of Glass Waste on the Flexural, Compressive, and Direct Tension Bonding Strengths of Masonry Bricks

T he waste material problem in today's world has become a major topic affecting all sectors of human life. Researchers are interested in providing solutions for each kind of waste material. Waste glass is one of the waste materials whose amounts increase daily. This article deals with two types of modified cement mortar with glass granular in the masonry wall to find their effect on the wall's property (direct tensile, flexural, and compressive bond strength). Seven different mixes were prepared according to the used glass granular ratio (three mixes contained white glass with 15, 20, and 25% while three of them contained green glass granular 5, 10, and 15%, and the last mix was a controlled mix which contains no glass granular).Based on the obtained result, the used white glass granular provides optimum compression and direct tensile bond strength when 20% of sand is replaced with white glass granular; optimum direct tensile bond value was obtained, which increased by 1.4% and increased compressive strength by 13.08% compared to control mortar. Green glass granular provides optimum compression and direct tensile bond strength when 10% of sand is replaced, direct tensile strength by 1.02%, and increased compressive strength by 3.7% compared to control mortar. The increase of the used waste glass granular in the mortar decreases flexural bond strength, and the amount of decrease depends on the chemical glass compositions.


Introduction:
Since the waste materials increased with the population and the requirement of life, continuously adding these materials to the landfill led to the impurity of the water sources and the landfill [Ogundairo et al., 2019, Altufaily et al., 2019. For these reasons, waste materials must be collected, reused, or recycled [Zeng et al., 2020]. Waste materials include different types and can be reused for different functions, such as eggshells as cement replacement [Abdulhameed et al., 2021], plastic waste as fibre in concrete [Abdulhameed et al., 2022], scraped tire as recycled rubber aggregate [Abdulhameed et al., 2021], waste crashed clay brick [Abaas et al., 2022]. One of these materials is waste glass; its waste increase day after day is glass since it has so many functions in human life [Papadogeorgos and Schure, 2019]. Based on the provided data in Figure1 [EPA, 2018] represent, the number of glasses produced by tones in the US between 1960 to 2018 as landfills. These subjects take interest many researchers to find a way to reuse this amount of waste glass instead of putting it on the land, including using the waste glass as partial replacement of sand in the mortar [Zeng et al., 2020] or using with other waste material inside mortar or concrete [Al shemaree et al., 2022]. Mortar can be used in plastering or as bonding between masonry units since masonry has the oldest history today and is used in wall construction [Kamal et al., 2014, Lourenço., 1998]. Walls are subjected to different loadings, such as bending, gravity, or seismic loads. Real structure size cannot be tested to find the effect of these different loads; for this reason, a small-scaled size will be used [Sathiparan et al., 2008]. These loadings supported by bonding include the shear bond strength [Sathiparan et  , using modified mortar must satisfy the required amount of the bond to be stable during subjected to these loads. This article deals with applying the mortar modified with waste glass granular as a partial replacement of sand in the masonry walls and finding the effect of the used glass granular in the mortar on the flexural, compression, and direct tension bonds between masonry units and obtained mortar.

Methodology:
Seven different mixes of mortar have been prepared, the first one without any addition of waste glass, while three of these mixes have been modified with white waste glass using 15, 20, and 25 % as a partial replacement of fine aggregate in mortar, another three mixes have modified with green waste glass using 5, 10 and 15% as a partial replacement of fine aggregate in a mortar [Ahmad, 2022]. These seven mixes have been used to prepare samples for compression, direct tension, and flexural bond strength to find the effect of  Figure 3; an SEM test has been done to show the microstructure of waste glass as in Figure 4 and Figure 5, while their physical properties and chemical composition have been described in Figure 6 and Table 1. The used cement was obtained from the Taslwja Cement Factory (35.6224746, 45.2115668) in Sulaimani City; the cement's chemical composition and physical properties are shown in Table 2 and Table 3, respectively. These properties are observed to conform to [ASTM, C150., 2005]. The SEM image of the used cement particle size and its texture are shown in Figure 7.

Mix proportions:
Based on the provided condition in [ASTM C1329., 2016], a mix composition of 1:2.5 has been chosen as cement to the sand ratio for the required mortar type (M). Used mortar must pass flow condition 110±5 as in [ASTM C109., 2021] and obtain by using a w/c ratio of 0.67. Used replacement ratios of glass were as follows for each type of glass (white and green bottle glass). Mortar compositions have mixed as described in the [ASTM C305., 2020].  Based on the obtained Result, Direct tensile bond strength increases when the mortar contains 10% of green glass granular as a sand replacement and provides tensile bond strength higher than the control mortar by 1%, while this percent becomes 1.84% when the mortar modified with 20% of white glass.

Compression bond strength:
This test was used to find the bond strength between mortar and masonry brick when November 2022 Volume 28 98 three samples have been prepared, a total of twenty-one samples prepared as in Figure 12, and subjected to the load rate as in Figure 13, causing the failure of the sample between 1 to 2 minutes, and the maximum applied load has been recorded. A compression bond has been found by dividing the failure load into the bond area. Obtained results are summarized in Table 8 and Figure 14 below:  Based on the obtained result, compressive strength bond strength increase when the mortar contains 10% of green glass granular as a sand replacement and provides compressive bond strength higher than the control mortar by 3%, while this percent becomes 13.8% when the mortar is modified with 20% of white glass, and in the most cases the failure mode faced shell separations as in Figure 15 below:

Flexural bond strength:
This test was used to find flexural bond strength in masonry, using [ASTM, E518., 2015]. Five samples have been prepared for each type of mortar, a total of thirty-five samples as in Figure 16. The weight of all samples, has been taken and recorded after the prepared samples have loaded at a rate that provides the failure of the sample in the time between (one to three) minutes, as shown in Figure 17. After loading, the maximum load, which provides the failure of the sample, has recorded as the maximum applied load, and the flexural strength founded using the equation below:   Based on the obtained results as in figure 18 and Table 9, the increase of the waste glass percent in mortar as replacement of sand decreases the flexural strength, and the amount of the decrease depends on the chemical composition of the glass granular.

Conclusions:
Based on the reviewed work and the obtained experimental data, the following points are obtained: 1-The effect of Waste glass granular in the mortar depends on its chemical compositions 2-When 20% of the sand was replaced with white glass granular, the optimum direct tensile bond value was obtained by 1.4% compared to the control mortar.
3-When 10% of the sand was replaced with green glass granular, the optimum direct tensile bond value was obtained, which increased by 1.02% compared to the control mortar.
4-When 20% of the sand was replaced with white glass granular, the optimum compressive strength value was obtained, which increased by 13.08% compared to the control mortar.
5-When 10% of the sand was replaced with green glass granular, the optimum compressive strength value was obtained, which increased by 3.7% compared to the control mortar.
6-Different percentages of waste glass (green and white colour) negatively affect flexural strength in a mortar, and the decrease depends on the chemical glass compositions.