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Article

Engineering Properties of Television Plastic Shell Waste (TPSW) to Replace Part of Sand–Cement Mortar

by
Chang-Chi Hung
1,
Chung-Hao Wu
2,
Her-Yung Wang
2,*,
Chun-Fu Lo
2,
Chien-Chih Wang
3 and
Shen-Lun Tsai
2
1
Department of Construction Site, Hoei Construction Co., Ltd., Yilan 269023, Taiwan
2
Department of Civil Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 807618, Taiwan
3
Department of Civil Engineering and Geomatics, Cheng Shiu University, Kaohsiung 833301, Taiwan
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(3), 1559; https://doi.org/10.3390/app15031559
Submission received: 14 December 2024 / Revised: 28 January 2025 / Accepted: 30 January 2025 / Published: 4 February 2025
(This article belongs to the Special Issue Advances in Cement-Based Materials)
Browse Figures
Versions Notes

Abstract

:
Adding domestic waste into cement mortar or replacing fine aggregate can effectively reduce the use of natural sand and gravel and reduce carbon emissions, thereby preventing waste from polluting the Earth’s environment. This study explored a sustainable method for recycling television plastic shell waste (TPSW) by using it as a partial replacement for sand in cement mortar production. By evaluating water–cement ratios (0.4, 0.5, 0.6), ages (3, 7, 28, 56, 91 days), and TPSW levels (0%, 5%, 10%, 15%), this research assessed key properties, such as the slump, compressive strength, and durability. The results show that the TPSW absorbed less water than natural sand, increased the number of pores and slightly reduced the strength. However, a 5% substitution led to a minimal performance loss after 91 days, while it improved the sulfate resistance and resistivity. Overall, incorporating 5% TPSW reduces the environmental impact and carbon emissions, offering a sustainable solution for cement production.

1. Introduction

Faced with depleting global resources, Taiwan, which is surrounded by seas, needs to efficiently utilize resources. In particular, water resources, ecosystems, and air pollution are significant issues [1,2]. Modern society has become a plastic-focused culture, with the use of plastics far surpassing that of other materials, such as ceramics, metals, and glass [3]. Commonly employed plastics in daily life include polyethylene terephthalate (PET), polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polystyrene (PS), polyvinyl chloride (PVC), and bioplastic polylactic acid (PLA) [4,5,6,7,8,9]. If household waste plastics could be used as fine aggregate replacements in cement products [10,11,12,13] or incorporated as fiber materials [14,15,16], this would significantly reduce the dependence on natural resources and thereby decrease their consumption. However, current research on incorporating household waste plastics into cement products primarily focuses on the inclusion of expanded polystyrene (EPS) [17,18,19,20,21].
In recent years, technological products have continued to advance, and TVs, as part of daily life, are being updated continuously with technology. Many outdated TVs are being eliminated and becoming domestic waste. How to dispose of domestic waste has become challenging for various countries. There are many TVs that can be broken down at environmental protection stations. During the process of dismantling television waste, particularly the back covers of cathode ray tube (CRT) televisions, large quantities of high-bromine polystyrene (PS) plastic are produced. As the number of CRT televisions being dismantled increases annually, the amount of recovered brominated PS plastic also increases. However, the brominated flame retardants (BFRs) in these plastics degrade slowly in the environment and possess bioaccumulative properties, posing potential environmental hazards [22].
In addition, the external parts of the TV are made of HDPS plastic products, which can be utilized after melt spinning but increase carbon emissions. These materials can be reused before melting to reduce carbon emissions [23,24,25]. The continuous development of TV technology has led to the disposal of outdated TVs in many countries. Civil engineering materials have been oriented toward green renewable resources and sustainable development [26,27,28]. If domestic plastic waste can be added to cement mortar or replace fine aggregates, the use of natural sand can be reduced effectively, and thus, the consumption of natural resources can be reduced. In recent years, the number of discarded TV sets has increased significantly. According to Table 1, due to the rapid changes in science and technology over the past ten years, discarded electronic equipment has become one of the fastest-growing special wastes worldwide [29]. Larger and thinner TV sets have become the main products, and old sets are replaced with new sets, resulting in a large amount of recyclable waste (mainly from factories and residences) [30]. The demand for TVs has increased significantly in recent years, from 1181 tons in 2013 to 30,560 tons in 2022. TVs are divided into internal electronic parts and external TV shells [31]. The TV shells can be processed into recycled plastic pellets by granulation plants and used as recycled plastic materials to implement resource recycling. Previous studies indicated that adding materials with different physical properties to traditional blends has advantages [32,33].
However, these materials must be economically feasible and align with comfort and sustainability criteria [34,35,36]. Some researchers attempted to incorporate such TPSW materials into concrete specimens to replace coarse aggregates [37,38] or partially replace fine aggregates to produce cement mortar, and then analyzed its compressive properties and establishing stress–strain models [39].
Wang, Ru, and Christian Meyer [37] investigated the use of recycled high-impact polystyrene (HIPS) as a sand replacement in cement mortar. Their findings revealed that substituting sand with HIPS led to reductions in both the compressive strength and splitting tensile strength of the mortar, with a notably smaller reduction observed in the splitting tensile strength. The incorporation of HIPS enhanced the ductility of the mortar and increased its energy dissipation capacity. Additionally, the HIPS reduced the dry density, dynamic elastic modulus, thermal conductivity, and water vapor permeability of the mortar, while having no adverse effect on its freeze–thaw resistance. Senthil Kumar, K., and K. Baskar [38] demonstrated that replacing 50% of the coarse aggregate with HIPS aggregate retained 50% of the concrete’s strength under all tested conditions. Their findings also indicated a linear relationship between the strength loss and the increase in the HIPS content. This type of concrete significantly reduces the unit weight of the material, making it suitable for use in earthquake-prone regions and for non-structural components, such as partition walls and lightweight roofing.
Research showed that not all of them are suitable for use as aggregates in concrete. Resin-based types of waste plastic and PET have been reported to have the highest rate of use for concrete production [40,41,42].
Current experimental results show that the mechanical and durability properties of concrete are altered due to the inclusion of plastic. However, such concrete still fulfils the requirements of many engineering applications [43]. In addition, the research results of Alkhrissat, T., indicate that plastic aggregates may be substituted for natural fine aggregates to create an environmentally friendly mortar with similar strength characteristics. [44]. This study used TPSW as a fine aggregate to investigate the fresh properties, engineering properties, and durability of cement mortar made from TPSW with different variables. Their relationships were further established to discuss the influence of different factors (W/C, substitution amount, and age) on the engineering properties of cement mortar.

2. Experimental Design

2.1. Experimental Materials

  • Cement: Portland type I cement produced by the Taiwan Cement Corporation was utilized. The image is shown in Figure 1a. Its properties complied with those of ASTM C150 [45], the specific gravity was 3.15, and the fineness was 3450 cm2/g; its physical properties are shown in Table 2.
  • Fine aggregate: River sand from the Laolong River. The saturated surface dry specific gravity was tested according to the CNS 487 specifications [46]. The saturated surface dry specific gravity was 2.65, and the water absorption was 1.9%. Its appearance is shown in Figure 1b, and its physical properties are shown in Table 2.
  • TPSW: The TV shell was made of HIPS and was provided by the manufacturer. The TPSW originally appeared in the form of black flakes. After being crushed by a crusher, the TPSW appeared in the form of a black powder. Its appearance is shown in Figure 1c, and its physical properties are shown in Table 2.

2.2. Test Methods and Items

This study tested cement mortars with different proportions of TPSW, using different substitution amounts (RMs) of 0%, 5%, 10%, and 15% and W/C ratios of 0.4, 0.5, and 0.6 to test its fresh properties (slump and slump flow), and it was transformed into a 50 mm × 50 mm × 50 mm cubic specimen and cured in saturated lime water. Its engineering properties (compressive strength, flexural strength, ultrasonic pulse velocity, and water absorption) and durability (resistivity) were tested at the ages of 3, 7, 28, 56, and 91 days. The proportioning unit weight is shown in Table 3.
The test items and specifications of this study are shown in Table 4.
(1)
Slump: according to the ASTM C109 specification, a mini-slump cone was used to conduct a test, and the slump method was used to measure the consistency of the fresh cement mortar to determine the workability of the mortar.
(2)
Slump flow: according to the ASTM C230 specification, which mainly measures the standard flow value of the cement mortar.
(3)
Setting time: according to the ASTM C403 specification to measure the standard water consumption of cement, the initial setting time and final setting time of the cement were used as a reference for understanding the properties of the cement and concrete construction.
(4)
Compressive strength: According to the ASTM C109 specifications, compressive tests were conducted at each age set by the institute to test the pressure-resistant properties of the various cement mortars. The schematic diagram of the testing process is shown in Figure 2.
(5)
Flexural strength: the flexural strength of the standard cement mortar was measured according to the ASTM C348 specifications.
(6)
Ultrasonic pulse velocity: The ultrasonic detector used complied with the ASTM C597 specifications and was used to measure the velocity of the ultrasonic waves that passed through the interior of the test object. This process measured the time it took for the ultrasound to travel through the specimen. By analyzing the transmission speed of the ultrasound in the different materials, insights into the internal conditions of the specimens could be obtained. Specifically, this test determined the transmission speed of a vibration energy pulse within the concrete component.
The process began with the pulser, which generated a short-cycle high-voltage signal. This signal caused the transmitter to vibrate at its natural resonant frequency. The transmitter’s vibration pulse was transmitted to the concrete via a coupling fluid and was then received at the other end through the concrete. When the receiver detected the pulse wave, the timing was stopped, and the elapsed time was displayed.
The pulse wave transmission speed in the concrete was calculated by dividing the straight-line path from the transmitter to the receiver by the elapsed time. This speed provided valuable information for estimating the strength and density of the concrete. The schematic diagram of the ultrasonic pulse velocity testing process is shown in Figure 3.
(1)
Water absorption: according to the ASTM C1585 specification, the specimen was put through the immersion test, and the water absorption was calculated after measuring the dry and saturated mass.
(2)
Resistance to sulfate corrosion: referring to the ASTM C1012 specification, the specimen was soaked in sodium sulfate solution, 5 cycles were performed, the weight loss was observed, and the weight loss rate was calculated.
(3)
Resistance: According to the ASTM C876 specification, by measuring the resistance value, when the resistance value was larger, the current flowing through the test object was smaller. The schematic diagram of the resistance testing process is shown in Figure 4.

3. Results and Analysis

3.1. Slump

Figure 5 shows the slump of the cement mortar made by replacing sand with TPSW and that the slump of the control group (0%) was 81.3% lower than that of the 15% TPSW group when the W/C was 0.4. When the W/C increased from 0.4 to 0.5, the slump of the control group was 55% lower than that of the 15% experimental group. When the W/C increased from 0.5 to 0.6, the slump of the control group was 31% lower than that of the 15% experimental group. When the W/C increased, the slump tended to increase because the increase in the water content reduced the cohesion of the paste and increased the slump, and the overall workability and fluidity of the cement mortar increased. Overall, the slump decreased as the amount of TPSW added increased. When the W/C increased, the overall slump increased as the water content increased, so the W/C had a greater impact on the slump than the substitution amount did.
As shown in Figure 5, the slump decreased significantly as the proportion of the TPSW materials replacing sand increased. When the water–cement ratio was 0.4, the slumps decreased by 25%, 68.8%, and 81.3% for the substitution amounts of 5%, 10%, and 15%, respectively. For a water–cement ratio of 0.5, the slumps decreased by 13.9%, 36.1%, and 55.6%, respectively. At a water–cement ratio of 0.6, the slumps decreased by 4.4%, 13.3%, and 31.1% for the same substitution levels. These findings are consistent with other studies [38], and the reduction in slump could be attributed to the flaky shape of the TPSW material, which did not perform as well as the coarse aggregate. While increasing the substitution amount reduced the slump, the research results indicate that the water–cement ratio had a greater impact on the slump than the substitution amount.

3.2. Slump Flow

Figure 6 shows a comparison of the slump flow of three W/C cement mortars with partial sand replaced by the TPSW. When the replacement of the TPSW for partial sand was fixed at 5% and the W/C was 0.4, the slump flow was 10.4 cm, and when the W/C increased from 0.4 to 0.5, the slump flow was 19.1 cm. When the W/C increased from 0.5 to 0.6, the slump flow was 23 cm. This research showed that the slump flow decreased as the waste PS substitution amount increased and the overall workability decreased. When the W/C increased, the slump flow of the paste increased with increasing water content. The W/C had a greater impact on the slump flow than the substitution amount did.
As shown in Figure 6, the slump flow decreased as the proportion of waste PS materials that replaced the sand increased. When the water–cement ratio was 0.4, the slump flow decreased from 13 cm to 9.5 cm; at a water–cement ratio of 0.5, it decreased from 20.5 cm to 17.4 cm; and at a water–cement ratio of 0.6, it dropped from 24 cm to 19 cm. The rough texture of the waste PS materials reduced the slump flow, which led to decreased workability. However, as the water–cement ratio increased, the slump flow improved due to the higher water content. Overall, the water–cement ratio had a greater effect on the slump flow than the substitution amount.

3.3. Setting Time

Figure 7 shows the cement mortar with different TPSW substitution amounts (0%, 5%, 10%, and 15%) and W/C ratios (0.4, 0.5 and 0.6). In the 0% control group, the W/C ratios were 0.4, 0.5, and 0.6, and the initial setting times were 251 min, 341 min, and 448 min, respectively; the final setting times were 598 min, 685 min, and 926 min, respectively. In the 5% TPSW substitution group, the W/C ratios were 0.4, 0.5, and 0.6, and the initial setting times were 238 min, 316 min, and 419 min, respectively; the final setting times were 556 min, 644 min, and 901 min, respectively. In the 10% TPSW substitution group, the W/C ratios were 0.4, 0.5, and 0.6, and the initial setting times were 231 min, 301 min, and 406 min, respectively; the final setting times were 542 min, 626 min, and 885 min, respectively. In the 15% waste PS substitution group, the W/C ratios were 0.4, 0.5, and 0.6, and the initial setting times were 226 min, 292 min, and 397 min, respectively; the final setting times were 509 min, 575 min, and 842 min, respectively. An increase in the overall water content led to partial secretion of the cement paste, while the hydration heat reaction slowed, which prolonged the setting time.
The research results also indicate that as the water–cement ratio increased, the setting time increased correspondingly. This occurred because the higher water–cement ratio led to an increased overall water content, which caused the cement slurry to bleed. As a result, the rate of the hydration reaction slowed down, which prolonged the setting time.

3.4. Compressive Strength

Figure 8 shows that when the W/C was fixed at 0.5 and at the age of 91 days, the compressive strength of the control group was 53.2 MPa, the compressive strength of the 5% TPSW substitution group was 48.8 MPa (−8.3%), the compressive strength of the 10% TPSW substitution group was 45.3 MPa (−14.8%), and the compressive strength of the 15% waste PS substitution group was 40.1 MPa (−24.6%). The findings show that as the waste PS had a lower water absorption than the natural sand, there were more water molecules in the specimen, which formed many pores and reduced the compressive strength; when the W/C was 0.5 and at the age of 91 days, the strength decreased by 8.3% when the substitution amount was 5%. When the substitution amount exceeded 10%, the strength decreased by more than 10%. It could be inferred that a W/C of 0.5 and a TPSW substitution amount of 5% were the most effective at removing waste to attain the goal of waste recycling.
Since the water absorption rate of the TPSW material was lower than that of natural sand and gravel, there were more water molecules in the mix, which led to the formation of additional pores, which, in turn, reduced the compressive strength. As shown in Figure 9, under different water–cement ratios (W/Cs), the compressive strength decreased linearly as the proportion of TPSW increased. The slopes of these three curves were nearly identical, indicating that the reduction in the compressive strength was independent of the W/C ratio, which is consistent with previous research findings [38].

3.5. Flexural Strength

Figure 10 illustrates the flexural strength development of the cement mortar made with varying replacement levels of the TPSW materials as partial sand substitutes under a fixed water-to-cement ratio of 0.5, with the control group serving as the baseline. At 3 days, the flexural strength of the control group was 10.4 MPa. For the 5% replacement, the strength was 9.5 MPa (−8.7%); for 10% replacement, it was 8.9 MPa (−14.4%); and for 15% replacement, it was 7.8 MPa (−25.0%). At 28 days, the flexural strength of the control group increased to 13.3 MPa. The 5% replacement group achieved 12.1 MPa (−9.0%), the 10% replacement group reached 10.8 MPa (−18.8%), and the 15% replacement group achieved 10.1 MPa (−24.1%). At 91 days, the control group achieved a flexural strength of 14.9 MPa, while the 5% replacement group reached 13.5 MPa (−9.4%), the 10% replacement group achieved 12.5 MPa (−16.1%), and the 15% replacement group recorded 11.5 MPa (−22.8%).
When the water-to-cement ratio was fixed at 0.5 and the curing period was extended to 91 days, a 5% replacement level resulted in a flexural strength reduction of only 9.4%. However, when the replacement level exceeded 10%, the strength reduction consistently surpassed 10%. These findings suggest that a 5% replacement level under these conditions was the most effective for utilizing waste materials, thus achieving the goal of recycling and reusing TPSW materials.

3.6. Ultrasonic Pulse Velocity

The effect of adding the TPSW to the concrete was evaluated using the ultrasonic pulse velocity (UPV), as shown in Figure 11. With a fixed water–cement ratio of 0.4, the ultrasonic velocity of the cement mortar ranged from 3788 m/s to 4630 m/s for the substitution amounts between 0% and 15%, measured over 3 to 28 days. At a water–cement ratio of 0.5, the velocity ranged from 3937 m/s to 4505 m/s, and at 0.6, it ranged from 3788 m/s to 4032 m/s. The results show that as the water–cement ratio decreased and the curing age increased, the UPV gradually rose. However, as the substitution amount of the TPSW increased, the UPV decreased, which reflected the impact on the mortar’s density.
Despite the decrease, within the studied substitution range, the UPV at 28 days reached 3650 m/s, indicating that the specimens retained good density and strength. As the TPSW content increased, more internal pores formed, which led to the reduction in UPV. In summary, lower water–cement ratios and longer curing periods resulted in higher UPV values, while an increased TPSW content tended to lower the UPV due to the reduced material density.

3.7. Water Absorption Rate

As shown in Figure 12, the effect of varying the replacement levels on the water absorption of cement mortar was analyzed under a fixed water-to-cement ratio of 0.5: At 3 days, the water absorption of the control group was 8.8%. For a 5% replacement, the absorption increased to 9.0% (+2.3% compared with the control group). At 10% replacement, it rose to 9.7% (+7.8% compared with 5%). At 15% replacement, the absorption reached 10.2% (+5.2% compared with 10%). At 91 days, the water absorption rates for the replacement levels of 0%, 5%, 10%, and 15% were 7.1%, 7.4%, 8.3%, and 8.5%, respectively. Compared with the control group, the increases were +4.2%, +16.9%, and +19.7% for 5%, 10%, and 15%, respectively.
The water absorption showed a decreasing trend with prolonged curing periods due to the completion of hydration reactions. In the early stages, incomplete hydration led to a higher porosity and a less dense structure, which resulted in higher absorption rates. By 28 days, the hydration reactions were more complete, which reduced the porosity and consequently lowered the water absorption. However, as the TPSW replacement level increased from 0% to 15%, the water absorption rose. This increase was attributed to the lower water absorption capacity of the TPSW compared with the natural sand, which caused excess water molecules in the mortar, which created more internal pores and ultimately increased the water absorption.

3.8. Resistance to Sulfate Attack

Figure 13 illustrates the weight loss rates of cement mortar samples with different replacement levels of TPSW material under a fixed water-to-cement ratio of 0.5: At 3 days, the weight loss rates for the replacement levels of 0%, 5%, 10%, and 15% were −8.4%, −7.5%, −6.9%, and −6.4%, respectively, with a 23.8% difference observed between the control group and the 15% replacement level. At 28 days, the weight loss rates decreased to −6.3%, −5.3%, −4.6%, and −4.3% for the same replacement levels, where the difference expanded to 31.7%. At 91 days, the corresponding weight loss rates were −4.9%, −4.7%, −3.9%, and −3.6%, with a 26.5% difference between the control group and the 15% replacement level.
As the replacement level of the TPSW material increased, the weight loss rate of the cement mortar consistently decreased across all the curing periods. This indicates an improvement in the resistance to environmental degradation. The decreased weight loss rate was attributed to the enhanced sulfate resistance of the TPSW material compared with natural sand. The inert nature of the TPSW material reduced the susceptibility of the mortar to sulfate attack, which led to less material degradation over time. The findings suggest that incorporating the TPSW material into the cement mortar can significantly improve its resistance to weight loss due to external chemical attacks. However, this benefit must be balanced against potential impacts on other mechanical properties to ensure optimal performance in practical applications. In conclusion, using the TPSW material as a sand replacement in the cement mortar not only enhanced the durability against sulfate attack but also contributed to sustainable waste management by recycling post-consumer plastics effectively.

3.9. Surface Resistivity

Figure 14 presents the results of a four-electrode resistivity analysis on the cement mortar samples produced with varying levels of the TPSW material as a partial sand replacement. This study was conducted at a fixed water-to-cement ratio of 0.5: At 3 days, the resistivity values for the replacement levels of 0%, 5%, 10%, and 15% were 8.1 kΩ-cm, 8.5 kΩ-cm, 8.9 kΩ-cm, and 9.2 kΩ-cm, respectively, with differences from the control group within 13.5%. At 28 days, the resistivity values increased to 11.2 kΩ-cm, 12.3 kΩ-cm, 13.5 kΩ-cm, and 14.2 kΩ-cm for the same replacement levels, where the differences expanded to within 26.8%. At 91 days, the resistivity values for the respective replacement levels reached 20.2 kΩ-cm, 22.3 kΩ-cm, 24.2 kΩ-cm, and 26.1 kΩ-cm.
The electrical resistivity of cement mortar increased with higher replacement levels of waste PS materials. At 91 days, all the samples exceeded 20 kΩ-cm, which met the durability benchmarks for resistance to ion penetration and environmental degradation. While the increased resistivity was desirable for durability, the trend was inversely correlated with the compressive strength and ultrasonic pulse velocity. This suggests that higher replacement levels, although beneficial for resistivity, could adversely affect the structural performance by increasing the porosity and reducing the material density. The enhanced resistivity indicates improved resistance to ionic migration, which is beneficial for long-term durability. However, the potential trade-offs in mechanical and structural performance must be carefully considered when optimizing the replacement levels for specific applications. Balancing durability with strength and integrity remains critical to achieving a sustainable and functional material design.

3.10. SEM Analysis

We utilized a scanning electron microscope (SEM) to observe the changes in the crystalline structure of the hydration product within the cement mortar, with a focus on the impact of the substitution amount of the TPSW.
For a water–cement ratios of 0.5 and a 5% replacement, the structural crystal image changes and pore distribution of the hydration products in the cement paste were observed using scanning electron microscopy (SEM) at 3 days and 91 days. In Figure 15, the observation results show that with the increase in the content of TPSW, the interfacial gap between the cement matrix and the plastic aggregate became larger, which weakened the adhesion of the matrix. Furthermore, the addition of the discarded TV casings resulted in the enlargement of the bubbles and an increase in the number of pores formed in the internal structure. At the age of 3 days, since the material had not yet completed the hydration reaction, the formation rate of the hydration products was slow, which resulted in more obvious pores and cracks in the matrix, which was particularly significant compared with the control group. However, when the age was extended to 91 days, the hydration products gradually filled the internal pores, which significantly reduced the number of pores, which made the structure denser and improved the overall performance of the matrix.

4. Conclusions

  • The slump and slump flow of the cement mortar made by replacing sand with the TPSW decreased as the amount of TPSW added increased. Since the TPSW was less smooth than natural sand, the slump and slump flow were reduced. When the W/C increased, the slump and slump flow increased due to the increase in the water content. When the setting time was prolonged, the W/C ratio had a greater impact than the substitution amount.
  • The compressive strength decreased as the amount of TPSW substitution increased because the waste PS was less water-absorbent than natural sand during mixing, which resulted in more water molecules. The cementing ability was degraded and pores were formed. A W/C of 0.5 and a TPSW substitution amount of 5% could effectively achieve the economic benefits of waste recycling.
  • As the amount of TPSW added increased, the flexural strength decreased. When the W/C was 0.5 and at the age of 91 days, the strength was reduced by 9.4% when the substitution amount was 5%. When the substitution amount exceeded 10%, the strength was reduced by more than 10%, showing that a W/C of 0.5 and a TPSW substitution amount of 5% were the most effective at removing waste for waste recycling.
  • Since the ultrasonic pulse velocity depends on the internal density of the specimen, when the W/C was 0.4 and the TPSW substitution amount was 5% at the age of 56 days, the ultrasonic pulse velocity was greater than 4500 m/s, indicating that the specimen quality was good. As the substitution amount and W/C increased, pores were formed inside, so the ultrasonic pulse velocity decreased. The velocity increased with age.
  • As the W/C and the waste PS substitution amount increased, the number of pores in the specimen increased, and the number of internal pores increased; at later ages, the water absorption distinctly decreased. The water absorption had a relative relationship with the ultrasound and strength. The higher the ultrasonic pulse velocity was, the denser the specimen, the lower the water absorption, and the greater the strength.
  • The weight loss results for the cement mortar show that the W/C ratio had a greater impact than the substitution amount. The weight loss increased with the W/C. As the substitution amount increased and as the sulfate resistance of the TPSW became greater than that of the natural sand, the weight loss tended to decrease. The weight loss was greater at an early age. The hydration was relatively complete at late ages, so the weight loss of the specimen tended to decrease.
  • The resistivity decreased as the W/C increased. Since the TPSW had a higher resistivity than natural sand, the resistivity increased with the substitution amount and age.

Author Contributions

Conceptualization, H.-Y.W.; Methodology, C.-H.W. and S.-L.T.; Formal analysis, C.-C.H.; Investigation, C.-F.L.; Resources, H.-Y.W.; Data curation, C.-C.W.; Writing–review & editing, C.-C.H. and H.-Y.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data is contained within the article.

Conflicts of Interest

First author Chang-chi Hung was employed by the Hoei Construction Co., Ltd., Taiwan. The research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Figure 1. Experimental materials.
Figure 1. Experimental materials.
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Figure 2. Schematic diagram of the compression test process.
Figure 2. Schematic diagram of the compression test process.
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Figure 3. Schematic diagram of the ultrasonic pulse velocity testing process.
Figure 3. Schematic diagram of the ultrasonic pulse velocity testing process.
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Figure 4. Schematic diagram of the surface resistivity testing process.
Figure 4. Schematic diagram of the surface resistivity testing process.
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Figure 5. Slumps of cement mortars with different W/C ratios and TPSW amounts.
Figure 5. Slumps of cement mortars with different W/C ratios and TPSW amounts.
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Figure 6. Slump flows of cement mortars with different TPSW amounts and W/C ratios.
Figure 6. Slump flows of cement mortars with different TPSW amounts and W/C ratios.
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Figure 7. Setting times of cement mortars with different W/C ratios and TPSW amounts.
Figure 7. Setting times of cement mortars with different W/C ratios and TPSW amounts.
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Figure 8. Compressive strengths of cement mortars with different TPSW amounts at different ages.
Figure 8. Compressive strengths of cement mortars with different TPSW amounts at different ages.
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Figure 9. Compressive strengths of cement mortars at 28 days with different W/C ratios and TPSW amounts.
Figure 9. Compressive strengths of cement mortars at 28 days with different W/C ratios and TPSW amounts.
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Figure 10. Flexural strengths of cement mortars with different W/C ratios and TPSW amounts.
Figure 10. Flexural strengths of cement mortars with different W/C ratios and TPSW amounts.
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Figure 11. Ultrasonic pulse velocities of cement mortars with different TPSW amounts at different ages.
Figure 11. Ultrasonic pulse velocities of cement mortars with different TPSW amounts at different ages.
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Figure 12. Water absorptions of cement mortars with different TPSW amounts at different ages.
Figure 12. Water absorptions of cement mortars with different TPSW amounts at different ages.
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Figure 13. Sulfate resistances of cement mortars with different TPSW amounts and W/C ratios.
Figure 13. Sulfate resistances of cement mortars with different TPSW amounts and W/C ratios.
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Figure 14. Resistivities of the TPSW cement mortars with different W/C ratios at different ages.
Figure 14. Resistivities of the TPSW cement mortars with different W/C ratios at different ages.
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Figure 15. SEM images of 5% TPSW cement mortar at different ages.
Figure 15. SEM images of 5% TPSW cement mortar at different ages.
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Table 1. Net resource recovery, Resource Circulation Administration, Ministry of Environment—Recovery Volume Statistics. (unit: kg).
Table 1. Net resource recovery, Resource Circulation Administration, Ministry of Environment—Recovery Volume Statistics. (unit: kg).
Year20132014201520162017
Waste TV 1,181,0041,118,7011,099,0311,021,74226,219,398
Year20182019202020212022
Waste TV 24,411,87122,601,10328,280,35329,026,48230,560,227
Table 2. Physical properties of natural sand and TPSW.
Table 2. Physical properties of natural sand and TPSW.
Physical PropertiesCementSandTPSW
Specific gravity3.152.651.17
Fineness modulus34503.093.04
Water absorption rate (%)-1.90.1
Table 3. Cement mortar proportions with different W/C ratios and TPSW amounts (unit: g/cm3).
Table 3. Cement mortar proportions with different W/C ratios and TPSW amounts (unit: g/cm3).
W/CRM (%)TPSWSandCementWater
0.4001567570228
5781488
101571410
152351332
0.5001482539270
5741408
101481334
152221260
0.6001407511307
5701336
101411266
152111196
Table 4. Test items and specifications.
Table 4. Test items and specifications.
No.ItemSpecificationPurpose
1SlumpASTM C109 [47]Determine the consistency of the freshly mixed cement mortar and determine the workability
2Slump flowASTM C230 [48]Determine the standard fluidity value in the cement mortar
3Setting timeASTM C403 [49]Understand the properties of the cement and reference for concrete construction
4Compressive strengthASTM C109 [47]As a reference for the mechanical strength of the specimen
5Flexural strengthASTM C348 [50]Determine the bonding strength of the cement mortar
6Ultrasonic pulse velocityASTM C597 [51]Understand the internal conditions of the specimen
7Water absorption rateASTM C1585 [52]Understand the internal porosity of the specimen
8Resistant to sulfate attackASTM C1012 [53]Work out the weight loss of the cement mortar
9ResistivityASTM C876 [54]Evaluating the corrosion activity of steel within the specimen
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MDPI and ACS Style

Hung, C.-C.; Wu, C.-H.; Wang, H.-Y.; Lo, C.-F.; Wang, C.-C.; Tsai, S.-L. Engineering Properties of Television Plastic Shell Waste (TPSW) to Replace Part of Sand–Cement Mortar. Appl. Sci. 2025, 15, 1559. https://doi.org/10.3390/app15031559

AMA Style

Hung C-C, Wu C-H, Wang H-Y, Lo C-F, Wang C-C, Tsai S-L. Engineering Properties of Television Plastic Shell Waste (TPSW) to Replace Part of Sand–Cement Mortar. Applied Sciences. 2025; 15(3):1559. https://doi.org/10.3390/app15031559

Chicago/Turabian Style

Hung, Chang-Chi, Chung-Hao Wu, Her-Yung Wang, Chun-Fu Lo, Chien-Chih Wang, and Shen-Lun Tsai. 2025. "Engineering Properties of Television Plastic Shell Waste (TPSW) to Replace Part of Sand–Cement Mortar" Applied Sciences 15, no. 3: 1559. https://doi.org/10.3390/app15031559

APA Style

Hung, C.-C., Wu, C.-H., Wang, H.-Y., Lo, C.-F., Wang, C.-C., & Tsai, S.-L. (2025). Engineering Properties of Television Plastic Shell Waste (TPSW) to Replace Part of Sand–Cement Mortar. Applied Sciences, 15(3), 1559. https://doi.org/10.3390/app15031559

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