4.1 Introduction

This chapter represents the result of the samples being tested with various tests. The tests used in this research project were carried out according to the methodology described in Chapter 3, flexural and compression tests. The tests are conducted to fulfill the project’s requirement, which is to see the ability of perforated polymer concrete as a wave breaker. The results are analyzed and tabulated in the table, graph, and figure forms.

4.2 Materials

In this section, the properties of granite quarry dust aggregate and jute fabric will be discussed. The gradation and specific gravity of aggregate also tensile strength of jute fabric will be analyzed.

4.2.1 Granite Quarry Dust Aggregate

Pawar, et al., (2016) stated that in practical words, aggregate is the essential constituent. The aggregate gives shape to the concrete, limit shrinkage, and influence the economy. The determination of aggregate gradation can determine the void content in concrete. Optimizing aggregate gradation often increase concrete’s rheological, thermal, and resilience properties. Proper aggregate gradation provides a workable concrete mix that can be quickly compacted, but it also eliminates concerns linked to plastic concrete, such as the propensity for sorting, bleeding, and lack of qualified air and plastic cracking. The particle size distribution of aggregate, as calculated by sieve analysis, is called aggregate grading. Aggregate grading consisted of various sizes of aggregate that would have lower voids because the small particle aggregates would fill gaps between the void formed from big aggregates.

The result from lab works then will be compared to the requirement of ASTM C33 or AASHTO M6/M43. ASTM C33 or AASHTO M6/M43 specifications provide for a reasonably wide variety in the gradation of fine aggregates. ASTM C33 enables the usage of aggregates that fall beyond the limits because it can be shown that high-quality concrete can be made from such aggregates. With specific concretes, fine-aggregate scoring within the boundaries of ASTM C33 (AASHTO M6) is usually adequate (Kosmatka & Wilson, 2011). The aggregate grading from ASTM C 33 and result from lab works are plotted in Figure 4.1. Figure 4.1 shows that the quarry dust passing by 0.6mm sieve is above the maximum aggregate grading from ASTM C 33.

For the specific gravity of granite quarry dust aggregate, the result is 2.5. The aggregate size used is in the range of 1.18mm to the pan of the sieve. The standard specification test is following BS 1377-2 clause 8.3.

Figure 4.1: Gradation of granite quarry dust aggregate

4.2.2 Jute Fabric

Jute fabric is the highlighted material in this project where it gives better results in improving the flexural strength of polymer concrete. The previous study did show the jute fabric has a good potential in reinforcement. The tensile strength for the jute fabric can be seen in Table 4.1 (Arju, et al., 2015).

Table 4.1 Tensile strength if jute fabric

4.3 Mechanical Properties of Polymer Concrete (PC)

In this section, PC cubes and beams were prepared. The beams divided into two types, which are beam with jute reinforcement and without reinforcement. The prepared cubes and beams were tested for compressive and flexural strengths.

4.3.1 Compression Strength of Polymer Concrete (PC) Cube

One of the most essential and valuable properties is the compressive strength of concrete. Concrete is used as a construction material to withstand compressive stresses (Metwally, 2013). Something very critical to evaluating polymer concrete is this compressive test of analysis. It is because compressive strength is one of the tests performed needed to assess material’s ability to resist compression breakage. The findings would be essential to the study of polymer concrete porosity and durability. The PC cubes used the same proportion of mixes as indicated in Chapter 3, which is 1 ratio of resin, 1 ratio of fly ash, and 2 ratios of granite quarry dust aggregate. The cubes with the dimension of 50mm undergo a compression test with a standard specification of BS EN 12390-3:2002. In this project, PC cubes were tested on 14 days after cured in room temperature.

Based on the result in Table 4.2, the 50mm PC cube’s compression strength was 104.19 MPa. Hamid & Hamza (2019) stated that the compressive strength of PC cube 50 mm using 25% unsaturated polyester resin results in about 78 MPa with the testing age of 24 hours. By looking at the result, it is compatible with past research. As in the 1950s, high strength concrete with a compressive resistance of 34 MPa (5000 psi) was considered. High-strength concrete is currently defined as concrete with a specified compressive resistance of 55MPa (8000 psi) or higher (Torres & Burkhart, 2016). Comparing the result with the criteria, the result of this project meets the requirement. Therefore, the PC’s compressive strength proved that this PC with mix proportion of 1 part resin: 1 part fly ash: 2 part granite quarry dust aggregate can be considered as high strength concrete. Furthermore, polymer concrete has greater compressive strength compared to Portland cement concrete (Kumar, 2016).

Table 4.2 Result of compression test of PC cubes with duration 14 days

4.3.2 Flexural Strength of PC Beam and Jute Reinforced PC Beam

Flexural examination partially assesses the tensile strength of the concrete. This checks a concrete beam or slab strength to survive the bending loss. Throughout this analysis, the PC’s strength production was carried out to test the flexural behavior over time. The PC used the same proportion of mixes as indicated in Chapter 3, which is 1 ratio of resin, 1 ratio of fly ash, and 2 ratios of granite quarry dust aggregate. Beam with dimension 40 x 40 x 160 mm was tested for flexural strength with 3 points methods, as in Figure 4.2. For this flexural test, the samples are classified into two different samples, which are reinforced with a double layer of jute fabric and without reinforcement. This test is essential to assess the impact of using jute fabric as additional PC reinforcement. The standard specification for the conducted test is ASTM C 293-2002. Knowledge of the correlation between strength and time is vital when a system is exposed to other loading forms in age later (Radhi, et al., 2015).  Thus, in this project, the samples were tested on 2, 4, 6, 24 hours, 3, and 7 days after curing at room temperature. One of the most extraordinary characteristics of PC is rapid hardening with high strength. Therefore, protecting the quality of polymer concrete by predicting concrete strength is essential (Jin, et al., 2017). In Figure 4.3, the raw data of the flexural strength of reinforced and non-reinforced samples is shown.

Based on Figure 4.3, PC reinforced with jute fabric shows a higher flexural strength than non-reinforced samples. According to the test for 7 days, the PC’s flexural strength increases by 5.33% when reinforced with jute fabric. The maximum flexural strength of samples reinforced with jute fabric is 21.37 MPa, while 20.23 MPa for specimens without jute fabric. This reveals that the jute fabric’s tension strength that is placed at the bottom of the PC samples can help increase the tension of the specimens. Thus, it increases the flexural strength of the samples in polymer concrete.

According to the result for the 3 days duration, the flexural strength is lower than the 24 hours result. This is because the weather is playing a vital role where it affects the curing temperature. Heat can accelerate the hardening process. But when raining, the hardening process is slowed due to cold weather. Reducing the temperature of the curing process reduces the mechanical properties of Unsaturated Polyester Concrete. The compressive strength is decreased as the curing temperature is lowered, the splitting strength and the flexural strength are decreased (Gao, et al., 2019).

Figure 4.2: Flexural test using 40 x 40 x 160mm using a beam with 3 points method

Figure 4.3: Flexural strength of PC beams reinforced with and without jute fabric

4.4 Mechanical Properties of Jute Reinforced Polymer Concrete (JRPC) Plate

In this section, JRPC plates were cast with a dimension of 150 x 300mm (B x H) and divided into two parts. Firstly, the thickness of JRPC plates will be determined by casting it into the various size of thickness and being tested on the flexural test if the result is higher than the total pressure calculated means that is the optimum thickness for the plate. Secondly, once the JRPC plate’s dimension was completed, the plate was cast into the various percentage of holes to see the effect of the flexural strength of the JRPC plate. Thirdly, the JRPC plate with various holes will undergo wetting and drying conditions, which is 12 hours immersed in 3.5% of sodium chloride solution and 12 hours in room temperature to see the effect of chloride ion on the JRPC plate. 3.5% of sodium chloride solution indicates seawater while wetting and drying are to consider the low and high tidal of seawater.

4.4.1 Optimum Thickness of JRPC Plate

As indicated in section 3.4.4 Part A, the optimum thickness of the JRPC plate must be determined in other to complete the dimension of the plate that needs to be cast and tested. The breadth and height of the JRPC plate are 150 x 300mm. This is the following ratio of 1:2 as for the proposed wave breaker plate dimension for site condition is 3000 x 6000mm. The proposed dimension for site condition is considering the maximum high tide recorded at Sarawak River.

Fullerton, et al., (2010) stated that field data obtained by Bullock and Obhrai (2001) indicates pressure on a breakwater of more than 383 kilopascals for an incident wave height of about 3.1 m (10 feet). In order to test the suitable thickness for the plate, the calculation of average pressure was calculated. The average pressure calculated is by using the dimension of the site condition plate. This is because when the flexural strength of the wave breaker plate in this project with the dimension of 150 x 300 mm (B x H) can sustain the total pressure means the site condition wave breaker plate also can resist the pressure exerted towards it. Summation of pressure value from field data and the average pressure calculated will be the total pressure exerted on the plate. The JRPC plate with fixed dimension for breadth and height cast with different size of thickness and tested. The thickness approved when the value of flexural strength higher than the total pressure, which is 0.3845 MPa.

The flexural strength for the 15mm thickness of the JRPC plate gives the result of 16.49 MPa, which is totally can resist the total pressure exerted on the JRPC plate. Therefore, 15mm is the optimum thickness for the JRPC plate. Figure 4.4 represents the illustration of the JRPC full plate.

Figure 4.4 JRPC full plate with dimension of 150 x 300 x 15mm (B x H x T)

4.4.2 Flexural Strength of JRPC Plate with Various Percentage of Holes

As the optimum thickness for the JRPC plate was determined, means the dimension of the JRPC plate was completed. The finalized dimension of the JRPC plate is 150 x 300 x 15mm (B X H X T). Using the same dimension as the JRPC full plate, plates with a different percent of holes were cast. The diameter size of the hole is 18mm. The holes percentage are 5%, 10%, 15% and 5% with different orientation and can be seen in Figures 4.5, 4.6, 4.7, 4.8. This is to analyze the performance of the JRPC plate with a different percent of holes.

According to the result in Table 4.3, the percentage of strength reduction of the JRPC plates was compared with the flexural strength of the full plate as the control parameter. All the samples give the result on strength reduction by more than 5%. Hence, the holes affect the strength of the JRPC plate as compared to the control sample. The flexural strength result still gives high results where it can still sustain the total pressure as calculated before. 5% hole with different orientation has the lowest in the strength reduction, where it gives the highest flexural strength amongst all the percentage of holes. By looking at this, the flexural of the JRPC plate also affected by the orientation of holes on the plate. This can be an objective for further finding.

Figure 4.5: JRPC plate with 5% holes

Figure 4.6: JRPC plate with 10% holes

Figure 4.7: JRPC plate with 15% holes

Figure 4.8: JRPC plate with 5% holes different orientation

Table 4.3 Result of flexural strength of JRPC plate with holes

4.5 Chloride Resistance of Jute Reinforced Polymer Concrete

In this section, the jute fabric reinforced polymer concrete beams, and plates were cast. These samples then being tested in flexural test after undergoing 28 cycles of wetting and drying condition, which are 12 hours immersed in 3.5% concentration of sodium chloride solution which represent the seawater and 12 hours in room temperature. The purpose of wetting and drying conditions is to consider the low and high tidal of seawater. The chloride resistance test is compulsory for seeing the durability of the JRPC plate in chemical resistance as a wave breaker plate was placed in the coastal area where there is a high possibility of being attacked by chloride ion. This part will be divided into two parts, which are chloride resistance of JRPC beam and chloride resistance of JRPC wave breaker plate.

4.5.1 Chloride Resistance of Jute Reinforced Polymer Concrete (JRPC) Beam

Beams with a dimension of 40 x 40 x 160mm were cast with jute reinforcement and undergo 28 cycles of wetting and drying conditions, which is 12 hours immersed in 3.5% concentration of sodium chloride solution represent the seawater and 12 hours in room temperature. By looking at Figure 4.9, the JRPC beam that undergoes the wetting and drying process in 28 days duration gives flexural strength 25.74 MPa, which is considered a higher result. Beam cure with room temperature gives the result of 21.37 MPa at a duration of 14 days. The result of the beam undergoes 28 cycles of wetting and drying is 16.98% higher than the beam cure with room temperature condition. This is because of the difference in the testing age. Even after 14 days, the hardening process of PC is still ongoing, which is not fully reached 100% of its strength. The PC is slightly affected by chloride attack, but the effect cannot be seen because the PC is not fully cured.

Ribeiro, et al., (2002) reported that PC samples immersed in sodium chloride solution showed the slightest decrease in flexural strength. Additionally, the flexural strength in the initial examination periods of 1,7 and 21 days was clearly increased and started to decrease at 56 and 84 days.

Figure 4.9: Result of the JRPC beam with different curing condition

4.5.2 Chloride Resistance of Jute Reinforced Polymer Concrete (JRPC) Plate

In this section, the JRPC plate was cast with different percentages of holes, the orientation of the holes, and the full plate. The holes percentage is 5%, 15%, and 5% with a different orientation. These plates were tested after undergoing 28 cycles of wetting drying condition, which is 12 hours immersed in a 3.5% concentration of sodium chloride solution represent the seawater. Chemical resistance test is compulsory as the JRPC wave breaker plate is placed at the coastal area where it exposed to chloride ion.

According to Figure 4.9, plates that undergo 28 cycles of wetting and drying immersed in 3.5% sodium chloride solution give higher results than plates cured at room temperature. This is because the plates were cast in different days and weather conditions. A polymer as a binder and critical component of PC is highly sensitive to the changes in temperature (Rarani, et al., 2014). The plates need to cure for more than 7 days in ambient temperature before the immersion process started. The same goes for plates that cure with room temperature also need to cure until it reached full strength and sufficient time to harden before being tested. The PC should be affected by the chloride attack, but because the plate is not fully cured, then the effect of ion chloride towards the PC cannot be seen. For 5% of plates with a different orientation, the result is way higher than the other plates with holes. As discussed before, the orientation of holes did affect the flexural strength of the plate. Our primary focusing here is the chloride attack on the JRPC plate. Thus, overall the result gives a positive response where the flexural strength of the JRPC plate is still higher even immersed in 3.5% of sodium chloride solution.

Figure 4.9: Result of the JRPC plate with different curing condition

4.6 Summary

After all the samples undergo compression and flexural tests, the results than being analyzed to study the mechanical and durability properties of PC. After 14 days duration of compression test completed, the PC gives a higher result, which is categorized as high strength concrete. PC reinforced with jute fabric increased the flexural strength of PC compared to non-reinforced PC, and this is proved that jute fabric is good at being reinforcement to the concrete as it is more economical than others. The PC plate with holes affected the PC’s flexural strength, but the value still gives a great result and is considered high. As the PC plate placed in the coastal area, immersion with sodium chloride is compulsory to test the ability of PC to resist the chemical. When the PC plate tested with the flexural test, the result is slightly higher as the PC plate had not reached its full strength before immersion started. However, others finding reported that PC has high resistance towards the chemical. For sodium chloride solution, the PC only affected a little. Thus, from the results above, PC has proved that it has the potential to be used as a wave breaker plate in the coastal area.