Palm Shell Ash Research Articles

Synthesis of Zeolite-A From Oil Palm Shell Ash for Ferrous Metal Adsorption in Borehole Water

Synthesis of Zeolite-A From Oil Palm Shell Ash for Ferrous Metal Adsorption in Borehole Water

Investigation of Strength Concrete Materials Using Pozzolanic Additives

In the study, pozzolanic materials serve as replacements for additives, namely Palm Shell Ash (PSA), Coal Fly Ash (CFA), and Rice Husk Ash (RHA). The purpose of the study is to determine the optimum proportion of additives used in high-performance concrete. The addition of 15% PSA resulted in a strength of 69.227 MPa over a test period of 56 days, while the addition of 15% CFA yielded a strength of 69.369 MPa, and the addition of 5% RHA resulted in a strength of 59.984 MPa. The maximum concrete strength is achieved by adding 15% PSA. Correlation analysis between stress-strain indicates that aggregates exhibit higher strength compared to cement paste, mortar, and concrete, highlighting the relationship between the aggregate, cement paste, mortar components, and concrete as a composite material. Aggregate strength values found to be the highest among concrete, cement paste, and mortar, indicating that cement paste contributes the least to the strength of concrete, followed by mortar as concrete reinforcement. The results suggest that aggregates remain the primary strength component supporting concrete. The finding indicates that the relationship between the basic substances in this study aligns closely with existing theory. Moreover, it suggests that all concrete materials with pozzolan variants can classified as high-quality concrete. The optimum percentage is obtained by adding 15% palm shell ash, resulting in the highest compressive strength compared to counterparts and test objects with other types of pozzolan additions. The relationships between the constituents of concrete demonstrate that aggregates continue to be important contributors to concrete strength, with the cement paste contributing the least. Concrete strength values fall between those of aggregates and those of cement and mortar pastes.

Utilization of Palm Shell Ash as a Filler in Making AC-WC Type Porous Asphalt

The background to the research that will be carried out is that the large amount of standing water on the road pavement in each rainy season results in disturbances to motorists' comfort. This is due to impermeable road pavement and poor drainage along the road. Porous asphalt can increase rainwater absorption, thereby reducing puddles on the road surface. Porous asphalt is a new breakthrough in the world of road pavement to reduce the appearance of puddles of water when it rains. Porous asphalt is also designed to have high porosity so that water can flow through side channels and a waterproof base layer to prevent water from seeping into the subbase layer and road body so as to minimize puddles of water on the road surface which often occur after rain and disrupt the smooth flow of traffic. cross. Advances in road pavement technology have encouraged researchers to conduct research using palm shell ash (fly ash) as a filler in porous asphalt mixtures. The use of palm shell ash is expected to increase the stability value and have large cavities so that water can pass through the road surface, as well as to reduce palm oil waste in Indonesia. The objectives of this research are 1. To find out the optimum asphalt content value in porous asphalt mixtures, 2. To know the results of using palm shell ash at 0%, 1% and 2% as a filler for porous asphalt mixtures in flexible road pavement. The research method is Marshall and Permeability Testing. The tests that will be carried out on a laboratory scale use an AC-WC hot mix asphalt system with guidance, namely the basics of asphalt concrete road construction. The research results showed that by adding palm shell ash as a filler in making AC-WC type porous asphalt, it showed that the stability value was higher, while the permeability value was lower, meaning that the addition of palm shell ash to the porous asphalt mixture did not have a significant effect because it was smaller. air voids in the mixture. The addition of palm shell ash to the porous asphalt mixture increases the stability value which can increase the ability of road construction to accept loads, but the pavement layer is not permeable and water flows over the surface more slowly.

Stabilization of Fibrous Peat Soils with Addition Palm Shell Ash Waste

South Sumatra Province has a peat area of 1.4 million Ha. The distribution of peat soil in Ogan Ilir is 23,687.91 Ha. Peat soil has a low bearing capacity. This research aims to explain the effect of stabilization on peat soil characteristics. Peat soil samples were taken using the Block Sampling method. The research locations are Parit Village and Lorok Village, Ogan Ilir Regency. Peat soil needs better properties and is unsuitable for foundation soil for civil construction. To overcome this, one method of soil improvement is required, namely the chemical stabilization method: changing the chemical properties of the soil by adding a mixture. The mixture used is palm shell ash waste with variations of 0%, 10%, 15%, 20%, 25%. Soil properties (physical and chemical), SEM, EDS, PTS, and CBR tests were carried out to determine the effect of this mixture. Soil properties test results: water content () in Parit Village 226.39%, and Lorok Village 252.39%. The fiber content (FC) test results for Parit Village were 25.18% and for Lorok Village 28.01%. Peat soil is classified as fibrous peat soil. The CBR value for Parit Village was 4.60%, and Lorok Village was 4.16%. The results of the immersion CBR test showed that Parit Village had a curing period of 7 days, a variation of 5%, namely 4.68%. Look Village obtained the most outstanding results: a curing period of 14 days, a variation of 25%, and 4.76%. The CBR value obtained in this study is 3%-5% (average) when used for subgrade strength with compaction conditions depending on the road category.

Performance Characteristics of Nano Palm Shell Ash (NPSA) in Asphalt Mixture

One innovation in creating new materials that have superior properties compared to large-sized materials is to use nanotechnology. The uniqueness of nano materials is that the smaller the size of the material, the greater the surface area and performance characteristics of the material in the asphalt mixture. This research develops nano technology in asphalt pavement construction by making nano material from palm shell ash waste. The aim of this research is to determine the effect of adding palm shell ash nano material as a substitute for asphalt in the AC-WC mixture. The research method was carried out by testing the morphological characterization of the palm shell ash nano material using X-Ray Fluorescence (XRF) testing and Scanning Electron Microscope (SEM) testing, then continuing with testing the characteristics of the mixture using the Marshall testing method. The nano material used is palm shell ash material obtained from palm shell burning waste originating from Riau which is then processed into Nano Palm Shell Ash (NPSA) material using a ball mill. The asphalt used is Pen 60/70 asphalt produced by Pertamina. The use of NPSA material in asphalt modification with NPSA variations of 1%, 2% and 3% can improve the performance of marshal characteristics compared to conventional asphalt mixtures. It can be seen that the stability, flow, VFA and MQ values increase with increasing NPSA percentage in asphalt. Meanwhile, the VIM and VMA values decreased along with the increase in the NPSA percentage in asphalt. In addition, increasing the percentage of NPSA in asphalt can reduce the use of optimum asphalt content compared to conventional asphalt mixtures. Utilizing palm shell ash waste is the best alternative for improving the performance of asphalt in mixtures and is environmentally friendly and economical.

The Role of Superplasticizers on the Workability Consistency of ECC Mortar Fresh Mortar Due to an Increase in the Percentage of Palm Shell Ash

Engineered cementitious composites (ECCs) are composites that have better attraction properties and behavior than concrete. ECCs are usually formed from cement, water, silica sand, cementitious materials, fibers, and other additives with a certain proportion. In this study, there are three types of ECC mortars (types AME, EM, and TEM) where these types are differentiated by the amount of cement used, the quantity of water, and the number of sand used. Each type uses ashes of palm shells with the same proportions of 0%, 5%, 10%, and 15% of the weight of cement. According to trial and error during the workability test, the number of superplasticizers used also increased according to the increase in the percentage of ash in the palm shell, where the variation of superplasticizers achieved was 0.70%, 1.59%, 2.49%, and 3.40% of the weight of cement. Based on the results of the slumpflow test, the average diameter of the ECC freshly mixed mortar was between 88 cm and 106.5 cm, and the T500 slump flow was between 0.28 seconds and 1.39 seconds. The test results show a fairly good workability consistency of all ECC fresh mortars, although there has been an increase in the percentage of palm shell ash used. Superplasticizer turns out to be very important in maintaining consistent workability of fresh ECC mortar mix.

Workability Investigation on the Fresh Mix of ECC Mortar and Crumb Rubber (CR)-ECC based on Variations of Palm Shell Ash, River Sand, and Cement

Engineered cementitious composite (ECC) is a composite that has better tensile properties and behavior than concrete. ECCs are usually made of cement, water, silica sand, cementitious materials, fibers, and other additives. The term ECC mortar is used because the ECC does not use fiber. The cementitious material in this research uses palm shell ash, with a proportion of 5%, 10%, and 15% of the cement weight. As a replacement for the fiber, crumb rubbers are used, with proportions of 2.5%; 5%; 7.5%; 10% and 12.5% of the cement weight. Workability was measured based on slumpflow tests (with measurements T500 and slumpflow diameter). The objective of this study is to establish the workability of fresh mix of the ECC mortar and CR-ECC with variations in the addition of palm shell ash, cement, sand and crumb rubber. Based on the results of slumpflow tests, the average diameter for fresh ECC mortars ranges between 88 cm to 106.5 cm, and the T500 ranges from 0.28 seconds to 1.39 seconds. As for fresh CR-ECC mix, the mean slumpflow diameter is between 71 cm to 93 cm and the T500 ranging between 0.90 seconds and 1.68 seconds. All of these values meet the slumpflow requirements stipulated by EFNARC. Nevertheless, the workability of the fresh mix ECC mortar is more flowable than the fresh mix CR-ECC. This is because crumb rubbers are water-absorbing.

Influence of Steam Curing Temperature on the Characteristic of Self-Compacting Concrete Incorporating Palm Shell Ash

Self-Compacting Concrete (SCC) is proven as durable concrete and applied to constructions. In this paper, a study was conducted to analyze the influence of variations of steam curing temperature (SCT) and water/binder (w/b) ratio on the characteristics of SCC incorporating 10% Palm Shell Ash (PSA) as a partial substitution for cement mass. The SCT was arranged from 25 C to 80 C. The variation of w/b in the compositions of SCC was 0.325, 0.350, and 0.375. The results showed that using PSA, the variation of SCT and the w/b ratio influenced the workability of the fresh concrete. The PSA, SCT, and the w/b ratio affected the concrete compressive strength and mass density. The increased SCT caused a lighter density and greater compressive strength. However, the decreased compressive strength occurred due to an excessive SCT of 70 C and above. The SCT of 60 C, 10% PSA, and w/b ratio of 0.350 in the mixture produced the greatest compressive strength of 36.27 MPa at 28 days of age, while without SCT, the greatest compressive strength of 36.78 MPa was achieved at the age of 28 days containing 10% PSA and w/b ratio of 0.325. It indicated that the w/b ratio was more influential than the SCT on the increase of the SCC compressive strength.

Bearing capacity of Percut Sei Tuan clay stabilized with palm shell ash

Improvements to the bearing capacity of the soil have been carried out and developed at this time, one of which is the stabilization of clay soils. There are several alternatives to solve low soil bearing capacity, one of which is using geo-synthetic materials but has a weakness in terms of high cost. Another alternative is to add palm shell ash as a stabilizing agent. The effect of adding palm shell ash has not been thoroughly studied, so further research is needed. The material added is palm shell ash with a variation of 0%, 4%, 8%, 10%, and 12% in each test. The tests carried out in the laboratory were water content (w), specific gravity test (Gs), Atterberg limit test, sieve analysis (sieve analysis), soil compaction test, and CBR (California Bearing Ratio) test. The CBR test was carried out by curing the soil for 1, 3, 5, and 7 days with a mixture of palm shell ash before compaction. The soil in this study belongs to the A-7-5 group. The CBR (California bearing ratio) value increased with the increase in the palm shell ash percentage in the mixture after curing the soil. The highest CBR value was in the variation of 12% palm shell ash with a 7-day curing period of 6.92% with a soil bearing capacity of 5.06.

Pemanfaatan Limbah Padat Kelapa Sawit untuk Pemurnian Minyak Goreng Bekas

The solid wastes of palm oil are palm shell and boiler ash which can be used as adsorbents. Adsorbent is a solid substance that an adsorption process which is used for the refining process of used cooking oil. Used cooking oil is oil derived from leftover cooking oil which has a higher saturated fatty acid content than new vegetable oil. This study aims to determine the process of making adsorbents, the process of refining used cooking oil, and the effect of adsorbent variations on the purification of used cooking oil. This research was carried out with the adsorption process, adding 15% of the adsorbent variation. The process of making the adsorbent was carried out by dehydration, carbonization at 6000C, and activation with 3% HCl for 24 hours. The results of the optimum adsorbent variation were 100% palm shell adsorbent with the results of analysis on used cooking oil after adsorption, namely: 0.05% water content, 0.58% ALB content, and 1.7 mgO2/100g peroxide number.

Study on Early Compressive Strength of Mortar- and Crumb Rubber-Engineered Cementitious Composites Contain Variation of Cement, Palm Shell Ash and River Sand

Study on Early Compressive Strength of Mortar- and Crumb Rubber-Engineered Cementitious Composites Contain Variation of Cement, Palm Shell Ash and River Sand

Pemanfaatan Limbah Sabut dan Tempurung Kelapa Sawit sebagai Silica Gel

The increase in the area of oil palm in Indonesia also causes an increase in the amount of palm oil waste. Waste in the form of coir and palm shells is thrown away. While the content of silica (SiO2) in both materials is feasible to be utilized. Silica gel is a form of utilization of oil palm coir and shells. The results of X-Ray Fluorescence (XRF) analysis showed that the silica (SiO2) content in palm coir ash was 27.5%, while 36.10% was in palm shell ash. Silica gel is an adsorbent produced by the sol-gel method, namely the formation of a gel derived from precursor compounds. The precursor compound in the formation of silica gel is sodium silicate solution (Na2SiO3) which is produced from the extraction process of coir ash and palm shells using sodium hydroxide (NaOH) solvent. The concentration of NaOH used varied, namely 1, 3, 5, 7, and 9 M. The aging times used for the formation of silica gel also varied, namely 4, 8, 12, 16, and 20 hours. Dry silica gel with the highest quantity of 5.4115 grams was obtained by adding NaOH with a concentration of 9 M and a aging time of 20 hours. While the silica gel which has the most suitable water content and Fourier Transform Infra Red (FTIR) graphic pattern with Kiesel Gel 60 G is silica gel resulting from the addition of 3M NaOH with a aging time of 8 hours. However, the results of the Structural Equation Modeling (SEM) analysis of silica gel showed results that were not in accordance with silica gel in general.

Effects of Physical and Mechanical Properties of Soft Soil on Subgrades Performances in Lubuk Bayas Village, Serdang Bedagai Regency

Generally, the existence of soft soil in Indonesia will be a problem in the construction of highway construction. One factor that influences and needs to be known in road construction is the characteristics of the subgrade where the pavement construction will be placed on it. Poor soil characteristics can cause bumpy road surfaces, cracks, or other road damage. Therefore, before carrying out a soil improvement, it is necessary to know its characteristics through the physical and mechanical properties of the subgrade. This research was conducted in Lubuk Bayas Village, Serdang Bedagai Regency, North Sumatra Province. Tests of physical properties in this study include sieve analysis, water content, specific gravity, plasticity limit test, and liquid limit test. The soil shear strength test and California Bearing Ratio (CBR) test were carried out to test the mechanical properties using a Dynamic Cone Penetrometer (DCP). From the results of testing the physical properties of the soil, it was found that Samples 1, 2, and 3 were fine-grained soils with the percentage of soil passing the No.200 sieve greater than 50%. The USCS classification system shows that samples 1 and 2 of the soil are in the Lean Clay (CL) group, while sample 3 is in the Fat Clay (CH) group. Samples 1, 2, and 3 include soils with high plasticity because the PI value is >17. The results of testing the mechanical properties of the soil Sample 1 obtained the value of c = 0.1299 kg/cm2 and Ø = 13.2°, in Sample 2 obtained the value of c = 0.1075 kg/cm2 and the value of Ø = 11.2° and in Sample 3 obtained the value of c = 0.1275 kg/cm2 and the value of Ø = 11.9°. DCP testing on samples 1, 2 and 3 obtained CBR values of 5.35%, 4.73% and 3.15%. From the CBR results, it can be seen that the soil in this location has a low soil bearing capacity, so if it is to be used as a subgrade layer, it will be necessary to repair the soil first so that structural damage does not occur in the future. Soil improvement can be made by stabilizing the soil using natural materials to maintain environmental sustainability. Natural materials that can be used include sand with certain gradations, stone ash, palm shell ash, and various other natural materials.

Morphology of Oil Palm (Elaeis guineensis Jacq.) Seedlings Under Drought Stress with Oil Palm Shell Ash and Aspergillus niger treatment

Climate change is a limiting factor that contributes to weather anomalies such as varying rainfall intensity. Weather abnormalities impact plantation crops, such as oil palm, which are very sensitive to water deficits, and inhibition of growth in the nursery phase reduces seed quality. In an effort to increase the resistance of oil palm seedlings to drought stress, palm shell ash is given because it contains high silicon (Si) ranging from 43% to 63%. Furthermore, the fungus Aspergillus niger is known to decompose and release insoluble silicon into orthosilicic acid into the soil solution, which can be absorbed by plants, This study used randomized block design with two factors drought stress factor with four level field capacity (FC) of 80%, 60%, 40% dan 20%; factor palm oil shell and Aspergillus niger 0, 10, 20, 30 g + 5 ml/polybag. The results showed that the parameter number of Aspergillus niger colonies before and after the drought stress treatment decreased, drought stress was also a significant difference in the parameters of plant height and number of leaves, while the treatment of oil palm shell ash with the addition of Aspergillus niger had no significant effect on plant height parameters and number of leaves of oil palm seedlings.

Synthesis and Characterization of Silica Gel from Palm Shell and Coir Ash

This study aims to determine the composition of the oxide, the characteristics of palm shell and coir, and silica gel synthesized. The oxide composition, crystallinity, palm shell and coir ash functional groups were analyzed using XRF, XRD, and FTIR. Analysis of the functional groups and crystallinity using FT-IR and XRD. The results showed the composition of SiO2 in palm shell and coir ash was 76%, and SiO2 in the form of quartz and cristobalite was more dominant than amorphous SiO2. The synthesis success was indicated by the appearance of peaks with low intensity, not sharp, and resembling bumps on the synthesized silica gel diffractogram, which is an amorphous SiO2 characteristic. This result is confirmed by FT-IR, where absorption at wave number 455 cm-1 is a Si-O-Si bending vibration, 783 cm-1 is a stretching vibration of Si-O symmetry of Si-O-Si, 3454.51 cm-1, and 3568 cm-1 with fairly high intensity are characteristic of the -OH group from Si-OH. The wide and sharp absorption at 1083.99 cm-1 is a stretching vibration of the Si-O symmetry of Si-O-Si, 1625.99 cm-1 is -OH vibration of water molecule, 798.53 cm-1 is Si-O stretching vibration of Si-O-Si and absorption of 462.92 cm-1 indicates bending vibration of Si-O-Si.

The Effect of Bentonite and Palm Shell Ash on The Mechanical and Physical Properties of Geopolymer Concrete

Geopolymer concrete is an alternative to obtaining environmentally friendly mortar by synthesizing materials that contain a lot of aluminum silicate. This study aims to determine the effect of bentonite and palm shell ash composition on geopolymers' physical and mechanical characteristics. All materials are mashed, mixed, and molded with a 5x5x5 cm3 cube. Ten specimens were prepared with bentonite - palm shell ash compositions are 40/45, 45/40, 50/35, 55/30, and 60/25 wt%. Meanwhile, the composition of NaOH, Na2SiO3, superplasticizer and water remained at 1.3, 7.7, 2, and 5 wt%, respectively. Then the samples were dried at room temperature for 24 hrs and heated at 60 °C or 80 °C for 12 hrs. The geopolymer concrete with the best characteristics was obtained with a composition of 40 wt% bentonites and 45 wt% palm shell ash by heating at 80 °C. This specimen has a compressive strength of 11.94 MPa with a density of 2.42 g/cm3, porosity of 8.43%, and absorption of 3.48%. The results have a chemical composition of 55.59% SiO₂, 9.45% Al2O3, and 8.22 Fe2O3 with a dominant quartz phase. Scanning electron microscope photo shows good bonding between particles, and there are no pores formed.

The effect of filler adding palm kernel shell ash on durability and marshall values properties of asphalt concrete mix

Lampung Province is one of the palm oil producers, especially in Way Kanan Regency. Way Kanan Regency has two palm oil-producing mills, namely PT. Sawit Indo Mas which is located in Kampung Tanjung Raja Sakti Blambangan Umpu and PT PLP which is located in Kampung Bumi Agung, Bahuga District. The two factories duce thousands of tons of Crude Palm Oil (CPO) vegetable oil daily produced from palm fruit plants (Elaeis Guineensis Jacq, Arecaceae). From oil management, it is undeniable that it can create a lot of solid waste from the palm shell. Meanwhile, the government has not made much effort to use the waste from the waste. When managing palm fruit, palm shells cannot be processed into oil because they have a hard texture, so the shells are discarded and become waste. Then we use the shell for research material as a filler. Palm shell ash has a silicon dioxide (SiO2) content which is also contained in Portland cement, so this content can allow the acquisition of a good asphalt mixture on the AC-BC layer. This study aims to see the effect of the effectiveness of adding shell ash fillers from palm shell waste in marshall test tests and value the resulting durability. The addition of fillers with percentages of 20%, 30%, 40%, 50%and 60%. From the results obtained from the test results in the laboratory that the addition of shell ash fillers of 40% gets better performance compared to shell ash with percentages of 20%, 30%, and 60%, with a higher state value of 1225 kg shown. In marshall testing, using palm shell ash fillers can increase the value of KAO. So that from the marshall test, the durability value of the sample immersion at the IRS value of 0% was 98.4% greater than the 40%, which was 91.13%. Overall, using palm shell ash fillers meets the minimum requirements of Bina Marga as an asphalt mixture. The degree of weather change in immersion durability affects the strength level of the marshall test.

INVESTIGATION OF SETTING TIME AND FLOWABILITY OF GEOPOLYMER MORTAR USING LOCAL INDUSTRY AND AGRICULTURE WASTE AS PRECURSOR IN INDONESIA

Geopolymer is a renewable construction material that reduces dependence on ordinary portland cement (OPC), where OPC manufacturing impacts carbon dioxide (CO2) emissions. The main aspect of geopolymers being studied is the precursor of pozzolanic material, used as a cement substitute because it contains aluminosilicate (Si-Al). Polymerization occurs between the precursors, reacted by alkaline activator solution (AAS). Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as AAS. In this study, local precursors from industrial waste and biomass were utilized. Fly ash was employed as a reference in the precursor by 5% - 10% substitution of glass powder, rice husk ash, bagasse ash, and palm shell ash. Moreover, 2% superplasticizer and 5% extra water were used to increase the flowability of fresh geopolymer. Tests were carried out on the setting time of paste, flow table, and compressive strength of geopolymer mortar. The tests were on the initial setting time of 25-75 minutes and the final setting time of 40-115 minutes. The setting time results revealed that the time of each substitution accelerated geopolymerization due to the substitution of precursors containing higher CaO and SiO2. Setting time and flowability/workability had a linear regression correlation (R2) of 0.95, with the flow table ranging from 180-250 mm. The compressive strength ranged from 25.88 – 36.36 MPa through a curing temperature of 70oC for 24 hours, followed by curing at ambient temperature for up to 28 days.

ANALISIS PENGARUH ASPAL MODIFIKASI DENGAN PENAMBAHAN ABU CANGKANG SAWIT TERHADAP KINERJA PERKERASAN ASPAL

This research uses oil palm shell ash as a filler of 1%, 2% and 3% of the weight and uses asphalt with 60/70 penetration, the method used is AASHTO and the specifications of Bina Marga 2018. This research was conducted to determine the characteristics and the optimum strength of the asphalt mixture using oil palm shell ash as a filler. From the resultsvof the tests that have been carried out, the averange value of the marshall test on the test object with 1% filler content is 290 kn/mm, the marshall value on the test object with a filler content 2% is 293 kn/mm, then the marshall value on the test object with a filler content of 3% is 293 kn/mm.

Pengaruh Penambahan Abu Cangkang Kelapa Sawit pada Tanah Lempung dengan Uji Direct Shear

The purpose of the study was to analyze the results of the physical properties of the clay used and to analyze the effect of adding oil palm shell ash to the clay on the direct shear test. From the results of testing the physical properties of the soil, the soil samples came from Jalan Yusuf Bauty, District. Somba Opu, Gowa Regency is an organic clay soil with moderate plasticity, according to the USCS soil classification system, the soil is classified as fine-grained OH group (organic clay with moderate plasticity and according to the AASTHO system the soil sample includes A-7-5. Direct Shear Test) with the addition of oil palm shell ash from the three samples, it can be seen that oil palm shell ash is able to increase cohesion (c) at each percentage addition of oil palm shell ash, but at the shear angle there is an erratic addition at each percentage addition of shell ash. palm oil, this is because oil palm shell ash only has tensile stress as a binder. From the results of research conducted, the addition of oil palm shell ash has an effect on shear strength, this shows that oil palm shell ash can be used for stabilization,