The Effect of Rice Husk Ash and Pineapple Leaf Fiber on Physical and Mechanical Properties of Concrete

ABSTRACT


Introduction
Today's technological development has given significant advancements in concrete types.Most buildings use concrete as their primary structure materials, especially buildings and long-span structures that require concrete with high compressive strength.Innovation should be continuously made to ensure the produced concrete is suitable for today's conditions [1].
Concrete is a composite of coarse and fine aggregates.Its shape is easily modifiable, depending on the materials.Concrete is fireproof, relatively cost-effective, easy-to-maintain, and easy to obtain.It can also hold a heavy load [2]- [5].Concrete is needed in all construction sites, such as foundations, bridges, roads, columns, floor plates, story buildings, and dams.
Various innovations have been made to improve concrete quality, including eggshell, clamshell, palm bunch ash, durian skin, lemon grass ash leaf, volcanic ash, pineapple leaf fiber, water hyacinth, fly ash, etc. [6] Pineapple leaf fiber (PALF) is underutilized despite its high fiber content.Rice husk ash (RHA) is a biomass waste with a specific property containing a pozzolanic compound that is rich in silicic acid (SiO2).It is used as the primary material of cement as an additional construction material in order to add the concrete production value [7]

Treatments for Rice Husk Ash and Pineapple Leaf Fiber
The tools and materials were prepared before conducting the study.Rice husk ash and PALF were put into a dish.The former was sieved using a 200 (0.0075 mm) sieve to prevent contamination.The specific gravity of RHA and PALF was tested after the sieving process.

Concrete Making Process
Cement, sand, 3/4 rock, RHA, and PALF were mixed following certain variations (Table 1).The cement, RHA, and PALF were mixed in a pan according to the predetermined composition to make them homogeneous.After that, the homogeneous RHA, PALF, and cement were then put into a mixer with crushed stone, sand, and water.The mixing was conducted for approximately 2-5 minutes to ensure the concrete paste was stirred evenly and inter-binding.Then, the concrete paste was poured into a cart.Onethird of the concrete paste was poured into a 10 x 20cm cylinder cast and a 50 x 50 x 15 block cast.The concrete was then mashed using an iron nail rod to ensure density.A vibrator was used to homogenize the mixture.It was reconfigured until the mold was complete.The sample was soaked in a tub after the mold surface was smoothened using a scrape.After being placed for 24 hours in a mold, the sample was soaked in a tub for 28 days.The casted concrete was then taken from the mold and coded accordingly.The concrete was left to dry for 24 hours and tested for its mechanical and physical properties.Figure 1 and Table 1 display the density values of concrete with various rice husk ash-pineapple leaf fiber compositions with the cast-in-situ method.The density value decreased as the composition of rice husk ash and pineapple leaf fiber increased, where sample A1 (composition = 0%) showed a density value of 2.510 x 10 3 kg/m 3 , sample A2 (composition = 2.5 %) showed a density value of 2.461 x 10 3 kg/m 3 , sample A3 (composition = 5 %) showed a value of (2.456 x 103 kg/m3), and sample A4 (composition 7.5 %) showed a value of 2.451 x 10 3 kg/m 3 .As RHA and PALF have a lower density than typical concretes, adding these two materials may increase the pores in concrete, leading to a lower density.In this regard, [8] show that more pineapple leaf fiber addition results in a lower density, whereas fewer PALF addition results in a higher density value.

Porosity Test
Figure 2. Porosity under variation of rice husk ash and pineapple leaf fiber composition Figure 2 displays the porosity of concretes made with additional RHA-PALF compositions.Porosity of samples A1 (composition = 0%), A2 (Composition= 2.5%), A3 (composition = 5%), and A4 (composition =7.5%) was 7.64%, 8.91%, 10.19%, and 12.02 %, respectively.Adding RHA and PALF was found to increase The concrete porosity.Therefore, the concretes tended o increase as a higher RHA-PALF ratio was added [9].This stated that the compressive strength tends to decrease as the porosity increases.As shown in Figure 3, every RHA-PALF concrete variation with the cast-in-situ method exhibited a high water absorption.Samples A1 (composition =0 %), A2 (composition = 2.5 %), A3 (composition = 5 %), and A4 (composition=7.5%),show the water absorption value of 0.323%, 2.5%, 0.361%, and 4.14%, respectively.Adding RHA and PALF was found to result in more porosity.A previous study found that higher RHA-PALF composition will likely result in larger pores, affecting the compressive strength test [10].4 show that adding more RHA and PALF to the concrete results in lower compressive strength.Higher RHA-PALF composition causes more pores and lower compressive strength than typical concrete.Samples A1, A2, A3, and A4 exhibited a compressive strength of 23.66 Mpa, 19.96 Mpa, 17.48 Mpa, and 16.45 MPa.This result is consistent with the previous research finding, showing that adding PALF decreases compressive strength.Figure 6 displays the morphology of Sample A2 using SEM-EDX from 500x, 1000x, 2500x, and 5000x magnifications with a ten μm diameter.In general, the samples in this study contained a homogeneous RHA silica lump, allowing sample A2 to have excellent mechanical properties.As displayed, the SEM-EDX test results contain elements like Al, Ca, O, C, and K from the Portland cement.SEM-EDX result showed that the sample contains 0.23± 0.03 % of silica, in addition to other Figure 7, which shows that the concrete was synthesized.The SEM-EDX analysis result shows a pitch-black color and pores formed on the surface, while the grayish white represents the distribution of RHA.This condition indicates that the samples can absorb the excess water.

Figure 7. SEM-EDX results
Figure 7 shows that the concrete was synthesized.The SEM-EDX analysis result shows a pitch-black color and pores formed on the surface, while the grayish white represents the distribution of RHA.This condition indicates that the samples can absorb the excess water

Conclusion
This study used the cast-in-situ method to make concrete based on rice husk ash and pineapple leaf fiber.Rice husk ash and pineapple leaf fiber were used as the cement substitutes with a different variation: Parameters examined in this study included density, porosity, water absorption, flexural strength, and compressive strength using a universal testing machine and material testing equipment, which were then analyzed morphologically using SEM-EDX.The result showed a density of 2.510 × 10 3 − 2.451 × 10 3 kg/m 3 , porosity of 7.64 -5.73 %, water absorption of 0.296 % -0.243 %, compressive Strength of 23,66 -16,45 MPa, flexural Strength of 33.3 -25.3 MPa.The morphological analysis showed that rice husk ash and pineapple leaf fiber mixed with concrete in this study has a porous structure.The EDX analysis result exhibited a high carbon percentage.

Figure 1 .
Figure 1.Density under variation of rice husk ash and pineapple leaf fiber.

Figure 3 .
Figure 3. Water absorption under variation of rice husk ash and pineapple leaf fiber

Figure 4 .
Figure 4. Compressive strength under variations of RHA and PALF Figure 4 and Table4show that adding more RHA and PALF to the concrete results in lower compressive strength.Higher RHA-PALF composition causes more pores and lower compressive strength than typical concrete.Samples A1, A2, A3, and A4 exhibited a compressive strength of 23.66 Mpa, 19.96 Mpa, 17.48 Mpa, and 16.45 MPa.This result is consistent with the previous research finding, showing that adding PALF decreases compressive strength.

Figure 5 .Figure 6 .
Figure 5. Flexural strength under variation of rice husk ash and pineapple leaf fiberAs shown in Figure5and Table5, the flexural strength decreased as the RHA-PALF percentage increased, with samples A1, A2, A3, and A4 showing a value of 33.3 MPa, 30.6 MPa, 28.6 MPa, and 25.3 MPa, respectively.The pineapple leaf fiber's poor mechanical properties and increased porosity due to RHA and PALF are responsible for the concrete's decreased flexural strength.3.6.Element and Microstructure Analyses of Sample A2

Table 1 .
The stress condition and parameters of samples

Table 3 .
Water absorption test result

Table 4 .
Compressive strength test result

Table 5 .
Flexural Strength Test result