Normal Concrete Mixtures Research Articles

Investigating mechanical properties of SIFCONs produced with waste PET fibers

It is known that slurry infiltrated fibers concrete (SIFCON) is a type of concrete that possesses superior properties. To reduce the initial cost of fibers and to overcome the detrimental effect of waste plastic this study has been attempted to use polyethylene terephthalate (PET) waste fibers to produce SIFCON mixtures and investigate their properties. Six SIFCON mixtures were produced in which three volumetric proportions of fibers (3 %, 5 %, and 7 %) and two aspect ratios (36.8 and 24.57) were used. Behavior of these mixtures was compared with a normal concrete mixture containing no fibers and having approximately the same compressive strength. Flexural testing was conducted for small prismatic specimens and also on large reinforced concrete beams. The behavior was evaluated in terms of flexural strength, toughness and ductility. The results showed better flexural strength in case of SIFCON mixtures compared to normal concrete mixtures for both investigated aspect ratios. In addition, toughness and ductility were significantly improved as PET fiber content increase. Moreover, enhancement in toughness and ductility is more obvious in case of first aspect ratio. SIFCON reinforced beams showed a ductile behavior and sustained more damage. The use of PET fibers can be considered a promising option to produce sustainable SIFCON mixtures with improved properties.

Utilization Of Waste In South Kalimantan as A Sustainable Technology Solution

Utilizing waste in South Kalimantan as a sustainable technological solution is an innovative step that has great potential in overcoming environmental and economic problems. This region, which is rich in natural resources, also produces waste from various sectors such as agriculture, industry and households. One solution that is being developed is processing waste into renewable energy. For example, fly ash waste, palm oil waste, candlenut shell waste, red brick powder and others can be processed into concrete mixtures which can be used as alternative materials. This recycling effort not only reduces the volume of waste that pollutes the environment, but also provides additional economic value. By utilizing waste effectively, South Kalimantan can reduce negative impacts on the environment, while encouraging greener and more sustainable economic growth. This effort shows the region's commitment to adopting environmentally friendly technology for a better future. These wastes can be used as a normal quality concrete mixture in accordance with standardization, the mixture of which is tested in the laboratory.

VARIATION OF TANGKILING AGGREGATE SIZE AND ITS IMPACT ON COMPRESSIVE STRENGTH AND ELASTICITY MODULUS OF CONCRETE

The use of coarse aggregate significantly influences the mechanical properties and overall quality of concrete. This study investigates the impact of different coarse aggregate sizes (10 mm, 20 mm, and 40 mm) on the compressive strength and elastic modulus of concrete at 28 days. The research was conducted as part of a thesis in the Building Engineering Education Program, Department of Vocational Technology Education, Faculty of Teacher Training and Education, Universitas Palangka Raya. The primary objective was to determine the compressive strength and elastic modulus values for concrete mixes using varying coarse aggregate sizes. The concrete mixtures incorporated different coarse aggregate sizes along with fine aggregate, water, and Portland Pozzolana Cement (PPC) type I from Gresik. The mix design followed the guidelines outlined in SNI 03-2843-2000 for normal concrete mixtures. Testing was performed on cylindrical specimens measuring 15 cm x 30 cm. Each aggregate size variation (10 mm, 20 mm, and 40 mm) was tested using 10 samples, and the tests were conducted at 28 days in the Laboratory of Building Engineering Education, Faculty of Teacher Training and Education, Universitas Palangka Raya. The average compressive strength at 28 days for the coarse aggregate variations of 10 mm, 20 mm, and 40 mm were 29.15 MPa, 28.60 MPa, and 28.50 MPa, respectively. The average elastic modulus at 28 days for the same variations were 3033 MPa, 3856 MPa, and 3950 MPa.

Penggunaan Limbah Abu Batu Sebagai Campuran Pada Agregat Halus Terhadap Kuat Tekan Beton

Stone ash is a fine aggregate that passes through sieve no. 4 (diameter 4.75mm) but is retained on sieve no. 200 (0.075mm), thus making stone ash a waste that is useful as a mixture of construction building materials because stone ash can function as a fine aggregate as a substitute for sand in concrete mixtures. The purpose of this research is to find out whether stone ash can be a suitable and good material as a substitute for some of the fine aggregate (sand) in a normal concrete mixture or not, to find out the results of the compressive strength test of concrete by stone ash in a normal concrete mixture, and what percentage composition stone ash which produces optimal concrete compressive strength tests or according to plan. The test object used was a 150 × 300mm cylinder with a total of 36 samples. Stone ash waste with composition ratios of 15%, 25% and 35% has a fairly good bond as an added material to normal concrete mixtures as a substitute for fine aggregate and can even increase the compressive strength of concrete significantly. The composition of stone ash used as a mixture for fine aggregate is 15%, 25% and 35% with a planned concrete quality of 20 MPa and a concrete age of 7, 14 and 28 days. The compressive strength produced by normal concrete without a mixture of stone ash aged 7, 14, and 28 days produces concrete compressive strengths of 13.63 MPa, 19.57 MPa, and 20.53 MPa. Next, for concrete with a rock ash composition of 15% of fine aggregate with an age of 7, 14 and 28 days, the concrete compressive strength is 15.75 MPa, 18.02 MPa, 22.03 MPa. Concrete with a stone ash composition of 25% of fine aggregate with an age of 7.14 and 28 days produces a concrete compressive strength of 15.96 MPa, 19.02 MPa, 21.16 MPa. Concrete with a stone ash composition of 35% of fine aggregate with an age of 7, 14 and 28 days produces a concrete compressive strength of 23.49 MPa, 24.31 MPa, 24.95 MPa. From the research conducted, the 35% composition has the highest compressive strength value of concrete among the other compositions

Automating the determination of low-temperature fracture resistance curves of normal and rubberized asphalt concrete in single-edge notched beam tests using convolutional neural networks

As materials undergo large-scale yielding or exhibit large sizes of fracture process zone in the crack tip region, multi-parameter fracture concepts should be employed to describe the complex crack-tip stress-strain fields. Fracture resistance curves (R-curves) are an established tool in characterizing the entire fracture process of such materials. However, for complex materials such as bituminous mixtures, the development of these curves is subject to experimental and computational intricacies. In this research, a framework is developed to automate the construction of R-curves for normal and rubberized asphalt concrete (AC) mixtures. AC mixtures are produced using PG58–22 and PG58–28 binders. Limestone and siliceous aggregates are used, and three binder contents are considered for the mixtures. Single-edge notched beam (SE(B)) fracture testing is conducted on AC beams with two different notch patterns. A convolutional neural network (CNN) model is developed and trained over 1260 test images with varying temperatures, notch geometries, and setups. The CNN model was used to detect the growing crack on the beam surface and each crack-detected image was sent to an image processing framework to measure the crack length. Crack extension increments were calculated and synchronized with test time and magnitude of load, load-line displacement, and cumulative fracture energy, and the R-curve could be constructed. A training accuracy of 0.91 was obtained for the model and a loss of below 0.10 as a result of a hyperparameter tuning indicating reliable classifications by the CNN architecture. The R-curves showed desirable agreement for control mixtures at temperatures of 0 °C and −15 °C. As the mixtures are rubberized, the R-curves showed favorable agreement in the crack blunting phase, transition zone, as well as the unstable propagation phase at −20 °C. Cohesive energy magnitudes were compared for the two methods with a Pearson coefficient of 0.81 while fracture rate and fracture energy magnitudes showed favorably close magnitudes with coefficients of 0.89 and 0.98 respectively.

PENGARUH PENAMBAHAN AM 78 CAIR TERHADAP KUAT TEKAN BETON FC’ 19,3 MPA DENGAN KONDISI FAKTOR AIR SEMEN TIDAK TETAP

Concrete is a mixture of cement, coarse aggregate, fine aggregate, water and with or without additional ingredients (admixture) in a certain ratio which will form fresh concrete. Many studies have been carried out to find alternative uses for construction because concrete is a very important element, considering its function as one of the structures most widely used by society. Concrete is a mixture of cement, coarse aggregate, fine aggregate, water and with or without additional ingredients (admixture) in a certain ratio which will form fresh concrete. The advantages of concrete as a construction material include having high compressive strength, being able to follow the shape of the building freely, being resistant to fire and relatively cheap maintenance costs. The aim of this research is to determine the effect of adding Liquid AM 78 on the compressive strength of concrete Fc' 19.3 MPa under conditions where the cement water factor is not constant. The method used in the research is SNI 63-2834-2000 procedures for making normal concrete mixtures. The conclusion from the test results was that the compressive strength value of standard concrete (BS) aged 28 days was 19.40 MPa which was greater than the compressive strength of the planned concrete, namely 19.30 MPa and the highest compressive strength value of concrete with the addition of AM 78 Liquid 1.0% (B .1.0) 28 days old is 20.57 MPa.

Influence Substitution of Tabas Stone Waste which Coated Polyester Resin to Concrete Compressive Strength

The need for the use of concrete raw materials is increasing in line with the increase in the use of concrete in construction. The availability of concrete raw materials is dominated by the exploitation of natural resources, namely components of cement, sand and crushed stone or gravel. If the availability of this material is exploited in excess, it will have an impact on environmental damage. On the other hand, many stone crafts for decoration and building ornaments in Bali also utilize tabas stone which is also exploited from nature, where the processed rock leaves a lot of waste that is disposed of without any wise processing actions. Tabas stone waste management is expected to maximize the utilization of natural resources and also reduce environmental pollution caused by the disposal of tabas stone waste that is not managed properly. This research is expected to provide an alternative to maximize the use of tabas waste as a partial substitution of crushed stone or gravel as coarse aggregate in concrete mixtures. The porous structure of tabas stone and the high level of water absorption in the concrete mix can reduce the compressive strength of the concrete. Steps to reduce water absorption in tabas stone are carried out by maximally closing the pores using a polyester resin coating. The study was carried out by making normal concrete mixture objects according to SNI 03-2834-2000. The percentage of substitution of crushed stone with waste stone that is coated with polyester resin is 0%, 25%, 50%, 75%, 100% of the required weight of coarse aggregate. The compressive strength of the concrete will be tested at the age of 7 and 28 days using a cylindrical specimen measuring 150x300mm. Test results in the laboratory showed that the coating of tabas stone using polyester resin was able to reduce the level of water absorption from 9.96% to 3.24% or 67.5% compared to tabas stone that was not coated with polyester resin. The optimum compressive strength of coarse aggregate substitution using tabas was obtained at variations of 50% crushed stone 50% tabas stone at the age of 7 days and 28 days, respectively, reaching 15.06 MPa and 21.55 MPa.

Evaluating the use of mucilage from opuntia ficus-indica as a bio-additive in production of sustainable concrete

The global demand for a sustainable and environmentally responsible economy, has called for incorporation of aspects of sustainability into infrastructure materials. Being the most globally consumed primary construction material, concrete’s strength and durability enhancement using green approaches is pivotal to sustainability of the built environment. Production of chemical admixtures is high energy consuming and environmentally taxing, thus the need for bio-available sustainable substitutes and/or supplements. This paper presents findings of an experimental and environmental impact evaluation, conducted on Normal Strength Concrete (NSC) mixtures dosed with Opuntia ficus-indica mucilage (Ofim) by mass-replacement of the mixing water. ASTM compliant tests for consistency, strength, and durability performance were conducted at standard time intervals up to 56 days, while the Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy were employed for concrete micro-characterization. The study explored the interaction between the natural bio-additive and synthetic commercial admixture. A comparative Environmental Life Cycle Assessment (E-LCA) was also conducted to assess resource use efficiency and quantify the environmental impacts of Ofim-modified concrete relative to conventional concrete. Test results showed that the use of Ofim led to slight increase in the compressive strength and elastic modulus, in addition to a pronounced impact on durability of concrete, resulting in reduced fluid ingress by up to 39%, a lowered decrease in K-values by 14%, and an increase in the freeze–thaw resistance with high retention of Relative Dynamic Modulus of Elasticity (RDME) in the Ofim-modified mix relative to the control mix. A 15% mixing-water mass-replacement resulted in an average reduction in greenhouse gas (GHG) emissions of 9.6%. Hence, even if the improvement in the mechanical performance is not substantial, a reduction in GHG emissions scales up as the concrete industry is huge and tremendously contributes to climate change through embodied carbon.

Pemanfaatan Abu Serabut Kelapa dan Serbuk Cangkang Telur Terhadap Kuat Tekan Beton

Indonesia is the largest coconut fiber producing country in the world and has not been able to process it optimally. Egg shell waste is also one of the wastes that is often encountered because many food raw materials use eggs. This research was conducted to determine the value of the compressive strength of concrete with the addition of coconut fiber ash and eggshell powder as a substitute for cement and which of the percentages of 0%, 0.5%, and 1.5% added mixture has optimal compressive strength for concrete quality. K – 225 or equivalent to 19.3 MPa at 28 days of age. The method used in this study is an experimental method according to SNI 03-2834-2000 concerning Procedures for Making Plans for Normal Concrete Mixture. The results of this study revealed that the addition of coconut fiber ash and eggshell powder to the concrete mixture decreased the compressive strength compared to normal concrete but not significantly. The average compressive strength value of normal concrete is 19.58 MPa. Whereas the compressive strength of concrete with the highest added material is the percentage of 0.5% coconut fiber ash and 0.5% eggshell powder with an average compressive strength of 19.30 MPa.

Assessment of Stone Ash as a Fine Aggregate Material to Meet the Value of Normal Concrete Compressive Strength

The concrete industry in Indonesia is very advanced and developing, so the use of construction materials is increasing. The need for other materials as a substitute for fine aggregate for the manufacture of concrete, namely stone ash comes from the stone slate industry waste. 20% stone ash, 80% sand) and (30% rock ash, 70% sand) with a concrete quality target of Fc' 17.5 Mpa. The method used is the laboratory experimental method referring to the SNI standard. The results showed that the use of stone ash (AB) as a normal concrete mixture affected the compressive strength of concrete. The higher the percentage of stone ash (AB), then the value of the compressive strength of concrete increases. The value of the compressive strength of concrete from stone ash (AB) at the composition of AB 10%, AB 20% and AB 30% was 173.50 kg/cm2, 235.11 kg/cm2 and 239.88 kg/cm2 while normal concrete was 18.59 MPa at 28 days.

Assessment of the Combined Effect of Silica Fume, Fly Ash, and Steel Slag on the Mechanical Behavior of Concrete

Every ton of cement produced emits half a ton of carbon dioxide, so there is an immediate need to limit cement use. Cementitious materials such as fly ash, silica fume, and steel slag can be substituted for cement in making concrete more rigid and stronger. This research work has been done to analyze the change in compressive strength in concrete, reducing the use of cement and coarse aggregate, in the case of varying percentages of cement replacement circumstances. To get this job done, there’s been conducted a variety of laboratory tests changing the partial cement replacement proportions with silica fume and fly ash and partial aggregate replacement with steel slag in the concrete mix. The test result showed that 15% silica fume, 10% fly ash, and 30% steel slag replacing proportion withstand more compressive load than the normal cement concrete mixture. The SEM test also supports the compressive strength test result by showing the internal bonding between the materials in the replaced binder-aggregate specimens. On the other hand, the flexural strength test came out with the best proportion of 15% cement replacement with fly ash and silica fume along with 10% coarse aggregate replacement with steel slag. The XRD patterns of the materials used also enumerate the standardization and testing procedures. The usage of sustainable cementitious materials like fly ash, silica fume, and steel slag incorporates the motivation behind reducing the industrial byproducts/wastes generated in such an amount that hampers our mother nature. The overall representation of this research will emancipate the initiatives taken toward greener and more sustainable construction.

Effect of concrete workability on bond properties of steel rebar in pre-cracked concrete

Although research has shown a considerable influence of the pre-cracking phenomenon on steel-congested concrete members, only normal concrete (NC) has been considered in the literature. The intention in this paper is thus to study the effect of the pre-cracking phenomenon on the bond response of pre-cracked NC with different slump flow values and self-consolidating concrete (SCC). Initial crack widths ranging from 0.0 to 0.5 mm are studied. Results show that initial crack widths larger than 0.10 mm have a significant influence on bond properties, such that reduction factors greater than 30% and 50% are obtained for the maximum bond strength of concrete specimens exposed to initial crack widths of 0.2 mm and 0.4 mm, respectively. Results show that concrete mixtures with higher workability are less sensitive to the pre-cracking phenomenon as compared to NC mixtures. The average bond stress of steel rebar in the pre-cracked SCC is found to be similar to that of the NC with a slump flow of 200 mm, which is considerably better than for NC with a slump flow of 97 mm. Moreover, results show that 65.8, 80.6, 88.5 and 93.1% fracture energy reductions are obtained for crack widths of 0.20, 0.30, 0.40 and 0.50 mm, respectively, as compared to the small crack width of 0.15 mm.

Pengaruh aditif limbah kerang darah (anadara granosa) terhadap kualitas beton K-225

A rapid development of the concrete construction sector has resulted in an increase in the need for concrete raw materials that are obtained directly from nature. The need for environmentally friendly materials is also increasing along with the development of construction engineering technology, so several studies have been conducted to search for an alternative to raw materials additives or concrete mixtures. Anadara granosa clam shell can be utilized as one of the alternative materials to substitute material for coarse aggregates. In this research, Anadara granosa clam shells of 10% and 13% were added to normal concrete mixtures, aged for 28 days, and then analyzed for characteristics and compressive strength. From the analysis of the results, it was found that an increase in the concrete compressive strength up to 103.67% or 233.47 Kg/cm2 with the addition of clam shells 10% to normal concrete mixtures, while the addition of more than 10% can reduce the concrete compressive strength. Scanning Electron Microscopy results showed a relatively rough surface and many pores on the surface of the concrete due to the addition of a clam shell. Finally, it can be concluded that Anadara granosa clam shells can be used as concrete additives with a maximum addition of 10% of the total weight of normal concrete.

Analisis Pengaruh Pencampuran Serat Karbon Terhadap Kekuatan Beton dalam Menahan Beban Desak, Beban Tarik dan Beban Lentur

This study aims to overcome the weaknesses of concrete, namely the nature of concrete which is classified as brittle so that it has a negative impact on the concrete in resisting bending and splitting, while it also has a high density (2.3-2.4 T / m3). So that this research will add fiber to concrete in the form of carbon fiber, carbon fiber that is very strong and is known to be very light is expected to increase the tensile strength and flexural concrete significantly and without adding weight to itself. Calculation of concrete mix planning using normal concrete mixture calculations (SNI 03-2834-2000) with a planned compressive strength is 20 MPa, carbon fiber mixed in the form of fiber pieces with variations in fiber length, namely 5mm, 10mm and 15mm with a composition of 0.4% of normal concrete weight. Tests are carried out when the concrete sample is 28 days old. While waiting for the concrete age to reach 28 days, the concrete is treated in the form of soaking in water. And the results of this study indicate a significant increase in concrete compressive strength of 45.32%; concrete tensile strength of 73.24%; and the flexural strength of the concrete was 78.83% but it also managed to maintain the density of concrete at 2.3 T / m3. For further discussion and more detail will be presented in the following research report.

Analisis Penambahan Serat Sabut Kelapa pada Campuran Beton

In the current technological era, concrete is one of the most widely used building materials in Indonesia, therefore good quality concrete will greatly support structural safety. In general, the people of Tolitoli have a lot of income from plantations, one of which is coconut plantations located in Dampal Selatan District, Tolitoli Regency. There are quite a lot of coconut plantations, and this causes the presence of coco fiber waste. In this study, the materials used for normal concrete mixtures consist of water cement, fine aggregate and coarse aggregate. The water used to mix the concrete is taken from the PDAM channel. To add coconut fiber to the concrete mix to determine the effect of adding coconut fiber to the compressive strength of concrete. The test objects to be made using a cube with a diameter of 150 mm, a width of 150 mm and a height of 150 mm, a total of 16 specimens with the design requirements, the compressive strength is based on the results of the compressive strength of the cube which has a size of 150x150x150 mm. to determine the compressive strength of cube-shaped concrete made and treated in the laboratory. The compressive strength of concrete is the load per unit area that causes the concrete to crumble. That is by performing a compressive test of concrete with a concrete compressive test tool that is available at the laboratory of the public works and spatial planning department of the Tolitoli district. The results obtained from the data analysis showed that the compressive strength of normal concrete at the age of 28 days was 22.63 MPa, for concrete with the addition of 0.5% coconut coir fiber at the age of 28 days it produced a compressive strength of 17.43 MPa, and decreased by 22.97% of the compressive strength of normal concrete, and concrete with the addition of 1.5% coconut coir fiber at the age of 28 days produced a compressive strength of 13.92 MPa and decreased 38.49% of the normal concrete strength, and for concrete that had added coconut coir fiber of 2.5% produces a compressive strength of 9.91 Mpa at the age of 28 days, a decrease of 56.21% from the normal compressive strength of concrete. 5% does not reach the planned concrete strength, which means that it is not yet suitable for use for 20 MPa concrete.

Pemanfaatan Agregat Sungai Mata Allo Enrekang Sebagai Campuran Beton

Mata Allo River is located in Enrekang, South Sulawesi. a river that has a fairly abundant source of aggregate material that has been used by the local community as a concrete-making material in the construction of small-scale construction. This study aims to determine the development of concrete strength based on concrete compressive strength, split tensile strength, flexural strength, and modulus of elasticity in normal quality concrete mixtures based on variations in the Water Cement Factor (FAS), namely Variations 0,49, 0,52 and 0,55 where the variation with the highest compressive strength is used to further testing. The Mix Design method used is the American Concrete Institute (ACI) method with a design concrete quality of 25 MPa. From the results of the study, the highest strength value was found in the FAS variation of 0,49 with an average compressive strength of 7 days, 14 days, 21 days, and 28 days, respectively, with a compressive strength of 16,977 MPa, 23,301 MPa, 25,276 MPa, and 26,691 MPa. The results of the research carried out, the characteristics produced from the Mata Allo river meet the SNI specification standard to be used as a concrete mixture.

Effect of molarity of NaOH and alkalinity ratio on compressive strength of geo-polymer concrete

Concrete is the most copious man-made material in the planet. One of the main ingredients in a normal concrete mixture is Portland cement. However, the production of cement emits approximately 5% of the world’s carbon dioxide (Greenhouse gas). On the other hand, the climate change due to global warming and environmental protection has become major concerns. The production of Portland cement involves the emission of carbon dioxide, thus replacing of the Portland cement with industrial waste can be one of the solutions for reduction of the carbon dioxide emission. At the same time, thermal power plants produce fly ash in a very large amount and it creates a huge problem for its disposal. Disposal of this fly ash requires approximately 40,000 ha of land every year. In order to avoid the above environmental issues as well as the disposal problem, researchers have employed fly ash an alternative of cement in making of concrete exploiting the binding property of fly ash thereby it led to make attempt to carry out more research on the replacement of cement by fly ash in the concrete. Therefore, the focus to work in this direction acquainting with the idea that the replacement of cement is possible with 100% fly ash and this alternative to regular concrete is known as Geo Polymer Concrete (GPC). The theme of the present work is fully replacement of cement with fly ash to produce the GPC. To produce the GPC, the main constituent materials used are Fly Ash (which is a by-product obtained from thermal power plants) and the alkaline activators in addition to aggregates and water. The alkaline activators used in this study for the polymerization are sodium hydroxide (NaOH) in flakes form and sodium meta -silicate (Na2SiO3) in gel form. The objective of the present work is to study the effect of NaOH molarity and alkaline activator ratios on the compressive strength (3, 7 and 28 days) of GPC at a constant curing period and curing temperature and compare with controlled concrete prepared using ordinary Portland cement (OPC). In the present work 5 and 10 M of NaOH and 1:1, 1:1.5 and 1:2 alkaline ratios were considered with constant curing temperature of 90° C and 24 h curing time. M20 grade of concrete mix design was carried out as per BIS (IS: 10262–2009) for control concrete and the same mix proportion was adopted for GPC also. From the experimental results, it was found that the both NaOH molarity and alkaline solution ratio effecting the compressive strength at 3, 7 and 28 days and maximum compressive strength was obtained at higher NaOH molarity (10 M) and medium alkaline solution ratio (1:1.5). Further, it was found that the compressive strength of GPC was higher than the controlled concrete prepared using OPC.

Analisis Karakteristik Serbuk Sabut Kelapa (Cocopeat) Sebagai Agregat Halus pada Campuran Beton

The advantages of coconut coir powder (cocopeat) are resistant to microorganisms, weathering and resistant to mechanical spelling, namely friction and blows. Based on these advantages, cocopeat can be used as a blend of fine aggregates in the manufacture of concrete. The sieve test was conducted on the cocopeat to determine the initial feasibility analysis of cocopeat as a blend of fine aggregates in the concrete manufacturing. The results of the cocopeat sieve test are that cocopeat is included in Region II which is classified as a fine module of slightly coarse grains with a fine module of fine aggregate grains of 2.37. This shows that cocopeat has a fairly good value in normal concrete mixtures but is not suitable for high resistance concrete mixtures that exceed 25 MPa. This was followed by a subsidence test that gave subsidence values for mixtures of concrete with a cocopeat composition of 25%, 50% and 75%, is 7.5 cm; 5.3 cm; and 2.2 cm. While a good subsidence ratio is used in the range of 6-18 cm. In addition, the concrete with a 25% blend of cocopeat has a stronger physical form and there are no fungus growing on the surface of the concrete. Meanwhile, concrete with a mixture of 50% and 75% cocopeat looks more fragile and forms molds on the surface of the concrete. Thus the concrete with a mixture of 25% cocopeat has better results.

PENGARUH SUBSTITUSI CANGKANG KEMIRI PADA SEBAGIAN AGREGAT HALUS UNTUK BETON K-250 TERHADAP KUAT TEKAN

Concrete is one of the most widely used materials in the construction industry. Concrete building blocks are materials that are widely found in nature, including sand and gravel and cement constituents. Candlenut shell is one of the additives or substitutes for aggregate which has recently been used. began to investigate the impact of its use on the mixture in concrete. The use of candlenut shells can be treated as a substitute for coarse or fine aggregate depending on the size of the pecan shell grains used. and to determine the optimum compressive strength of concrete by mixing candlenut shells as a partial substitute for fine aggregate with a percentage of 0%, 10%, 20%o and 30% of the weight of the fine aggregate. The research method is testing the compressive strength of concrete samples by carrying out laboratory test result. From the results of the concrete experiments that have been carried out and the data that has been obtained with the normal quality of fc 20.75 Mpa concrete and concrete with candlenut shell substitution for coarse aggregate in a mixture of 10%, 20%, and 30%, there are several conclusions, namely the age of concrete is 7, 14.28 days of mixed concrete of 10%, 20%, and 30% of the compressive strength experienced a decrease in the normal concrete compressive strength in every variation of the percentage. The results of the research of normal concrete and candlenut shell mixture on normal concrete 7,14,28 days are 10,74 MPa,13,86 MPa. 14.42 MPa, in 10% candlenut shell mixture 7.14.28 days which is 7.35 MPa. 10.75 MPa. 11.03 MPa, in the mixture of 20%% candlenut shells 7.14.28 days, namely 6.19 MPa, S.48 MPa 9.33 MPa, and in the mixture of 30%% candlenut shells, which is 6.79 MPa. 7,36 MPa, 8,77 Mpa/ Use candlenut shell for partial substitution of fine aggregate in concrete cannot be used as a material as a constituent of concrete.

Effect of Rice Conch Shell Powder as a Partial Replacement of Cement in Normal Concrete

Along with the increasing pace of development, many methods and research have been carried out and developed aimed at increasing the strength of concrete, one of which is by utilizing waste rice snail shells as a partial replacement of cement. This snail is considered a pest for farmers. Snail carcasses can also damage the environment and cause a bad smell. This can be used and utilized as an alternative material in concrete mixtures. The percentage of use of rice snail shell substitution varied, namely 0%, 10%, and 15%. The tests carried out were the compressive strength test, split tensile strength test, flexural strength test, and the modulus of elasticity of concrete with a concrete quality of 25 MPa. The test objects used were cylinders measuring 15 cm and 30 cm high and beams measuring 60 cm × 15 cm × 15 cm with variations in age of 7 days, 21 days, and 28 days. The highest value was obtained at 10% snail shell variation with 27,540 MPa, 2,735 MPa, 4,131 MPa, respectively. so that the 10% snail shell variation used in this study is still safe to use as a cement substitution material in normal concrete mixtures.