Analysis of Environmentally Friendly Concrete (Green Concrete) Using Coal Fly Ash as a Substitute Material for Portland Cement in Road Pavement

The development of technology in the field of construction, especially in concrete technology, is now becoming more rapid, which requires concrete materials that can adapt to the times. As well as for energy savings from normal concrete materials from a mixture of fine, coarse, cement and water can now be added to other materials. In this era, the use of cement for concrete making materials is very identical, therefore to reduce the use of cement, it is necessary to mix other materials. The research method that researchers use is the experimental-laboratory method by making test objects in the form of concrete cylinders with a size of 15x30 cm. Analysis of concrete testing using Fly Ash mixtures in this study there are several variations of fly ash mixtures, namely fly ash 50%, 60%, and 70%. In testing several Fly Ash mixtures produced a compressive strength value of 50% Fly Ash percentage and 2% Accelerator of 161.630 kg/cm2, 60% Fly Ash and 2% Accelerator of 154.189 kg/cm2, 70% Fly Ash and 2% Accelerator of 92.670 kg/cm2. In the results of this study with several variations of fly ash mixtures, the highest compressive strength value was obtained at a percentage of Fly Ash 50% and Accelerator 2%, which amounted to 161.630 kg/cm2 with the first variation test specimen sample at the age of 28 days of concrete.


Introduction
Besides water, concrete is the most abundant substance on Earth, according to some records 4,193,000 million tons of portland cement were consumed worldwide in 2015 Indonesia consumes about 60 million tons per year.The improvement of the world for some areas is indistinguishable from concrete, big business is the biggest client of this regular resource in the world.Environmental issues include the use of 12.6 million concrete natural raw materials in concrete each year, concrete production accounts for 5% of the world's CO2 emissions each year, and the weathering of many concrete structures makes them unusable.Utilization as a substantial framing material has a positive impact in the view of nature.Very fine buildup.The term "green concrete" refers to concrete as a building material that reduces its environmental impact by limiting or replacing the materials used [14].
The use of additional binders that can partially or completely reduce Portland cement in concrete, partially recycled materials to replace aggregate or cement.Use of high-strength materials that reduce the dimensions of concrete technology elements that must be environmentally friendly.Slightly Portland cement concrete uses a common supplementary binder such as fly ash in Portland cement or concrete ranging from 0%-30% the use of binders such as fly ash in larger quantities above 40% can provide many advantages in the form of by-products so that the price is much cheaper than Portland cement.Concrete Materials A little Portland cement for additional binders using and Portland cement.For filler materials coarse aggregate and fine aggregate [2].
In concrete, the percentage of concrete components for aggregate is 62%, Portland Cement is 16%, Fly Ash is 16% and water is 6%.The reason for using less Portland cement in concrete is that the concrete is more durable and has higher strength when fly ash according to specifications is used in the concrete, from coal/fly ash is a by-product of burning coal for electricity production so it is much cheaper than Portland cement [4].1321 (2024) 012043 IOP Publishing doi:10.1088/1755-1315/1321/1/012043 2 Concrete without Portland cement is used, which is the largest in Indonesia where there are coalfired power plants.Research results in many countries show that it can be utilized as a material in infrastructure development, the properties of concrete without Portland cement are equivalent to the properties of concrete in general so that there is no structural design code difference, the characteristics can reduce water requirements to achieve equivalent workability performance.In this study, coal fly ash was added to Fc 20 to make low strength concrete for rural road pavement.Therefore, in this final project, the researcher is interested in using coal to produce environmentally friendly concrete [1].

Preperation
The laboratory experimental method used during the research was done in the laboratory by making test objects in the form of concrete cylinders measuring 15 x 30 cm.This research was conducted at the Construction Material Technology Laboratory, Faculty of Engineering, Unissula.

Material
The materials used in the exploration are as follows: 1. Cement The concrete to be used is Gresik Cement with a load of 40 kg.

Fly Ash
Fly Ash is an additional admixture material 3. Fine Aggregate Muntilan sand is the fine aggregate used.

Coarse Aggregate
The coarse aggregate used in this concrete is a maximum size of 20 mm.

Water
The water used is water in the Engineering Faculty Laboratory of Sultan Agung Islamic University.

Accelerator
The addictive substance used is Accelerator

Tools
The tools used in this examination include: 1. Scales Scales were used to measure the total weight of the total and cement.

Sieve
The strainer involved is a total sieve with changes in strainer opening size of 4.80 mm; 1.20mm; 0.6mm; 0.3 mm and 0.015 mm equipped with a sieve cover and vibrated with a separating machine.

Estimating Cup
Measuring cups in this study were used to determine how much water and medication to assemble the substantial barrel-shaped samples.

Picnometer
The pycnometer in this study was used to determine the total dirt content.

Oven
The oven is used to dry the total so that it corresponds to the total setting required after the fresh concrete is mixed, a cylindrical concrete mold is used as a mold container.

Pressure Testing Machine
Pressure Testing Machine as a tool to determine the compressive value of the material being tested.7. Supporting Apparatus Some of the supporting tools used in this research are buckets, dippers, water hoses and others.

Mixer
Mixer as a machine used to stir concrete, mixers using capacity

Test Object
The substance of this examination is ordinary cement with various Fly Ash structures that correlate with the achieved compressive strength value of fc'20 track.Mix design is the process of creating test specimens after conducting tests (cleanliness of aggregates from mud, density, bulk density, water absorption, sieve analysis, and moisture).
The method used in the research for concrete planning, commonly used in normal concrete planning.Preparing the material composition for mix design further simplifies the mix design composition by determining fixed and changing variables.a.Fixed variables 1) cement 2) Fly Ash 3) Aggregate.4) Sand.b.Variables change 1) Percentage of fast track values at 7, 14 and 28 days of concrete opening.
2) The amount of water required to achieve different levels of flowability varies depending on the various mix design components and the changing composition of the materials.
The test specimens in each treatment as many as 30 pieces were placed in a test specimen in the form of a vessel with a size of 15 cm wide and 30 cm high.The following are the stages of manufacture: a. Prepare equipment for test piece production.b.Prepare supplies or materials according to the planned size.c.Put the aggregates into the mixer, and stir or mix until well blended.d.Put cement in the mixer, add water, and wait until it is well mixed.e. Add sand, add the remaining water that was previously added.f.Then, add the accelerator.After adding the Accelerator, the minimum mixing time is 3 minutes.If the mixture has not been diluted before adding the Accelerator g.Then stir until evenly distributed, to avoid separation.h.Then perform a slump flow test to measure the diameter of spread in self-compacting concrete.i. Add the specified dose of accelerator, working until the fresh concrete test meets the planned requirements.If the mixture at the time of analysis does not meet the requirements or not enough water.j.If the fresh concrete does not meet the requirements or is too liquid after adding the Accelerator dosage, the Accelerator mixture should be planned with a lower moisture content.k.After the concrete analysis meets the planned requirements, molding of test specimens can be carried out.l.After being in the mold for 24 hours, then remove it from the mold The treatment of Portland cement concrete is treated in the same way as normal concrete with the compressive strength test method carried out by immersing the object to be tested in water until it reaches a certain age.Soaking is carried out in order to maintain the influence on the weather during the hardening process on the concrete which affects the capacity of the concrete.The test plan was to determine the compressive strength and expansion effects of Fly Ash on samples made based on the mix plan.The tests were completed at 7, 14 and 28 days of age after concrete manufacture and curing.The test steps are as follows: a.The sample was taken from a puddle shower the day before the exam.a.Before testing, the specimens are dried by drying in the sun.b.The weight of the test specimen is first determined by weighing it.c. Make adjustments to the compressed media until the test piece is in the center of the lower and upper compression beams.Set the test piece on the scale.Make sure it starts from zero.d.To start the test, apply a compressive load from 0 to the maximum load (crack), then record the results.e. Calculate using the formula.

Fine Aggregate Sieve Analysis Check
From the several examinations carried out in the materials testing stage, the results of the fine aggregate and coarse aggregate examinations were obtained.The results of the fine aggregate inspection calculations performed should be seen in Table 2. below.

Material Testing Results
From several reviews conducted at the material test stage, the consequences of the total fine and total coarse assessments were obtained.Total inspection consists of moisture content inspection, sieving inspection and mud content.The examination of mud content was carried out using two experimental samples with experiment I of 270 ml and experiment II of 290 ml.From the results of looking at the water content of the total crude there is no reduction in the sample weight of the total crude as indicated by the typical moisture content value of 0%.The examination of mud content was carried out using two experimental samples with experiment I of 260 grams before washing then decreased in weight after washing to 225 grams and experiment II of 275 grams before washing then decreased in weight after washing to 270 grams.From the results of the examination of the mud content of the coarse aggregate, there is a decrease in the weight of the coarse aggregate sample, which is shown by the average mud content value of 2%.

Conclusion
Based on the results of research and calculations that have been carried out, the following conclusions are obtained: 1. From the several test results that have been carried out, for the compressive strength of a small amount of Portland cement fc 20, it was found that the best Job Mix Formula results were using a mixture of 50% and Accelerator 2%.Concrete with 50% fly ash mixture with an average of 13.766 (Mpa) Concrete with 60% fly ash mixture with an average of 10.912 (Mpa) Concrete with 70% fly ash mixture with an average of 6.935 (Mpa) 2. The addition and accelerator to the compressive strength of concrete gives a significant d in each result.In this study, the highest compressive strength value was obtained at a percentage of 50% and 2% accelerator, which was 161.630 kg/cm2 with the first variation of the sample specimen at the age of 28 days of concrete.

Advice
After conducting research, analysis and discussion of the compressive strength of a little Portland cement with a mixture and accelerator, the authors can suggest several things among them : 1. Considerations that can be taken for further testing on Portland Concrete Minimum Cement are that it can be tried as a substitute for other materials as a mixture variation by determining the material content.2. In accordance with the experiments that the researchers conducted with the composition and Accelerator for Portland Cement Slag Concrete needs to be studied further for further research.

Table 1 .
Fine aggregate screening data.

Table 2 .
Fine Aggregate Screening Results.

Table 4 .
displays the results of the fine aggregate sieve analysis obtained from the calculations.Below.

Table 4 .
Calculation Results of Coarse Aggregate Sieve Analysis

Table 5 .
Fine Aggregate Water Content Examination Data

Table 6 .
Fine Aggregate Water Content Check ResultAs a result of looking at the water content in both the total there was a decrease in the total sample weight in tests one and two by 10 grams with a typical water content of 4%.

Table 7 .
Fine Aggregate Sludge Content Examination Data

Table 8 .
Moisture Content Examination Data

Table 9 .
Moisture Content Check Result

Table 10 .
Fine Aggregate Sludge Content Check

Table 11 .
Sludge content inspection results

Table 12 .
Material Composition of normal betom

Table 13 .
Material Composition of Mixture using Fly Ash Mix Design At this stage, testing was carried out by modifying the Fly Ash mixture to use aggregate with a max of 20 mm.The following Job Mixed Design material requirements are required.

Table 14 .
Job Mixed Design Slump TestSlump testing was carried out on normal concrete samples.The normal concrete slump value is 120 mm, while the Slightly Cemented concrete slump value can be seen in the table below.

Table 15 .
The Result of Slump test

Table 16 .
Average Compressive Strength