Coarse Aggregate Replacement
Aggregate is an important part of the concrete and acts as inert material in concrete. Coarse aggregates are uneven and granular materials such as gravel, sand, or crushed stone, and are utilized for making concrete.
As concrete demand and consumption is increased rapidly demand of natural aggregate also rinsed. Similarly, the production of natural coarse aggregate is not sufficient ro satisfied these increased demand. Therefore, as a solution and to save environment the replacement of coarse aggregate in concrete is become essential.
Theare various alternative materials for coarse aggregate such as wastes of plastic, glass rubber, coconut shell, construction waste, quarry dust etc. can be used as replcememnt of coarse aggregate in concrete
What Is Coarse Aggregate?
The aggregates which are able to get retained on the 4.75 mm sieve or the aggregates that passes a size larger than 4.75 mm are referred to as Coarse aggregate.
One of the most important components of concrete is aggregate. The coarse aggregate provides concrete volume. The coarse aggregate in the concrete provides the hardness, strength and also providing the uniform quality of concrete.
Several building materials are utilized in construction work in the world. The coarse aggregate is one of the most common and widely used building materials in the construction industry.
The coarse aggregate is used in all construction projects, including roads & buildings, railways, etc. The coarse aggregates in concrete are chemically inert and are used only as filler material. The construction aggregates are mainly used to make concrete mortar in building construction.
What Is Need of Alternative Materials for Coarse Aggregate In Concrete
In construction cement, sand, and aggregates are vital materials. At current, a structure can not be built without those materials. In concrete, the total volume represents 75% to 80% due to its strength.
Recently, the demand for concrete has been increasing due to the enormous development in construction work. Moreover, studies indicate that around 10 % of all greenhouse gas emissions are included in the concrete formation.
They must be properly cleaned before they can be used to make concrete. Their angularity and strength impact the concrete in several ways. Unnecessary to say, the choice of these aggregates is an extremely important procedure.
Sustainable aggregate became a substantial requirement for considering the raw material shortages and environmental degradation.
Lightweight natural or synthetic aggregates produce lightweight concrete. It has a low cost and excellent durability. If we use alternative materials in construction, you can speed up the construction progress at a lower cost.
Alternative Materials for Coarse Aggregates
There are a number of materials available for the alternative for coarse aggregate in concrete. In concrete, we can alternate cement with reuse materials to reduce energy consumption. The list of wastes used in concrete can include fly ash, wood ash, blast furnace slag, or fumed silica. The partial replacement of coarse aggregate in concrete can bed done with alternative materials.
A special type of sustainable concrete is called green concrete. Another useful way to reduce greenhouse gas emissions from concrete is to replace aggregates. Recently, several reusable and recyclable materials are accessible for this purpose.
The various coarse aggregate materials used in concrete can be glass, rubber, expanded clay ash or plastic materials. On the other hand, alternative materials for fine aggregates in concrete may be very diverse, from asphalt to industrial by-products.
Replacement of Coarse Aggregate In Concrete
Several experiments discovered a number of alternatives to the original aggregate. There are various alternative materials for aggregate, as shown below.
- Fibrous concrete or papercrete
- Plastic Waste
- Glasscrete or Post-consumer glass
- Expanded Polystyrene Concrete
- Crushed rubber
- Coconut shell
- Construction waste material
- Quarry dust for partial replacement
- Plastic waste partial
- E-waste partial replacement
1. Fibrous Concrete Or Papercrete
Raw Materials Utilized For Papercrete
- Paper Slurry
- White lime or sand
- Portland cement
Manufacturing Process Of Papercrete
- Put waste paper or pulp into a water-filled channel dug out into the ground.
- The leave for 24 hours.
- Excess water is drained.
- The porportion of portland cement to paper sludge and white lime is 1:05:4.
- Add the required amount of water to ensure workability.
- For mixing the cement slurry, utilize a mixer. Perform this mixing process for at least 10 minutes.
Advantages Of Papercrete
- Papercrete is one of the cheap alternatives to concrete.
- Low-tech and reasonable equipment can be used.
- Papercrete is very light.
- The workability is quite neat completely, and different shapes can be given.
Disadvantages Of Papercrete
- The stiffness is lower than that of conventional concrete.
- According to B. Fuller(published in “Structural Properties of Unique Materials Made from Waste Paper”, 2007), the compressive strength of Papercrete 96 is 1.1MPa.The compressive strength of ordinary concrete is 15-70 MPa. Concrete limits its use.
- Low moisture resist.
2. Plastic Waste
Raw Materials To Create Plastic Concrete
- Discarded plastic materials
- Fly ash
Manufacturing Process Of Plastic Concrete
- When making plastic concrete, undergraduate students follow this production process, and the steps are as follows.
- Grinds plastic into finer flakes.
- Then expose them to short-term, harmless gamma radiation.
- Grind these flakes into fine powder.
- This plastic powder is mixed with cement and fly ash.
Advantages Of Plastic Concrete
- Plastic concrete has a wide range of uses.
- you can meet particular requirement by tailoring them.
- It the
- Lightweight compared to traditional materials.
- It can prevent vibration, water and chemicals.
- One of the most important advantages is that it is relatively durable and has a longer service life.
- Excellent electrical and thermal insulation properties.
- The cost of power generation is relatively low.
Disadvantages Of Plastic Concrete
- According to Md Hashmath and MdMeraj(published in: Experimental Research on Using Plastic Waste as Cement Mortar Aggregate, 2015), the adhesiveness of plastic is low. The concrete of this base material has low flexural, tensile and compressive strengths.
- Plastic concrete has a low melting point.
Glasscrete Raw Materials
The glass can be utilized as an alternate for fine aggregates in concrete. It is divided into No. 8 and No. 4 sieves. A number of studies were carried out to determine the modulus of natural sand using water-washed glass sand.
Cement, coarse aggregate, and glass concrete are components of this green concrete.
Manufacturing Process Of Glass crete
- The procedure of mixing all ingredients is the same as conventional concrete. However, steps to generate desired glass aggregates include a long method.
- Wash broken glass beads to remove harmful organics
- Dry these glass particles in an oven.
- Takeout the dried granules and cool.
- To obtain glass sand, put these particles in a grinder in Los Angeles.
- Store the crushed components for usage as fine aggregate.
Advantages Of Utilizing Glasscrete In Concrete
- The glass workability of concrete is better than natural sand.
- Improve the strength of concrete by using glass.
- Enhances the efficiency of concrete.
Disadvantages Of Utilizing Glasscrete
- According to Jared Robert Wright (published in: Concrete performance analysis, including recycled glass as a 100% fine alternative aggregate, 2012) one of the main problems of glass concrete is the alkaline reaction of silicon (ASR silica in glass will produce silica gel due to It reacts chemically with hydroxide ions in cement. As this gel consumes water, it creates cracks in the cement.
- In addition, the cleaning process is very complicated because any organic residues in the glass concrete will reduce the strength of the concrete.
4. Expanded Polystyrene Concrete
Expanded Polystyrene Concrete Raw Material
- Expanded Polystyrene beads of 1mm–3mm diameter
Manufacturing Process Of The Expanded Polystyrene Concrete
- Concrete mixer, add any colorant and water if required.
- In the mixer add the sand as well as Portland cement.
- Add the cement, sand, and water mixture completely.
- Add some Styrofoam particles and stir for another minute to make the particles absorb water.
- Then add the required amount of Styrofoam and mix well. If beads become hardens when consuming water, you can add water.
- When the mixture comes in the consistency of low slump and pourable texture, stop mixing.
- Pour this mixture into a mold, spread it on a flat surface and cover it with plastic wrap to harden the mixture.
- After 24 hours, remove the whole mix from the mold and enable it to cure entirely.
- The curing will take about one month. You have to keep the stone damp during this procedure. It will enable full-strength bonding to arise.
Advantages Of Expanded Polystyrene Concrete
- Expanded polystyrene concrete is 88% lighter than popular stone-based concrete. Therefore, structural support requirements like steel reinforcements and foundation size requirements are smaller. Moreover, it has decent insulation properties.
Disadvantages Of Expanded Polystyrene Concrete
- Polystyrene materials are sensitive materials. The strength is less than conventional concrete and can be utilized as light decorative bricks simply. You cannot use it to create concrete pavers.
5. Crushed Rubber
Raw Material Utilized For Crushed Rubber
- The vehicle tire reach the end of the usable life? In the case, you can utilize it as an alternate for coarse aggregates in concrete.
- The vehicle tires ground up to 3 mm to 10 mm in size to create crumb rubber.
Pros And Cons Of The Crumb Rubber
- The improvement of rubber to concrete withstands the failure and shattering of concrete. Yet during its mixing, the air is trapped in the mix. It outcomes in low compressive strength of the concrete mix.
6. Coconut Shell
Coconut shells can be used as coarse aggregate in concrete. It has functional resistance capability against abrasion, impact, and crushing.
When used as coarse aggregate in concrete, no special treatment of coconut shell is required. Coconut husks are easily crushed into grains and transportation of this material is very economical.
The chemical composition of coconut shells is summarized below.
- Material – – 0.6
- Coconut shell
- Cellulose – 27
- Lignin – 29
7. E-waste Partial Replacement
E-Waste, another main threat to the world with its huge volume of dumps to dispose of..
we have a tendency to are going out of land to lose them. Specialists try troublesome to urge rid of it.
What Is E-waste?
The idea is that all electronic items have a useful life after being disposed of, which is why it is called e-waste. They are included in televisions, laptops, CDs, pen drives, etc.
Using E-waste as a partial substitute for coarse aggregate in concrete is a worthwhile solution. We cannot completely change the materials in concrete because this will influence the workability of concrete.
The e-waste is crushed into the correct particle size and can be mixed with various aggregates in the concrete without affecting the quality and durability of the concrete. E-waste partial concrete is also called E-Crete concrete.
8. Construction Waste
construction waste is also very favorable as a substitute for coarse-grained aggregates in concrete.
It includes generally the demolished building parts like a portion of column, beam, slab, and masonry components.
In addition, some materials will be wasted during the construction process, such as boulders, bricks, etc. These materials perform well in concrete. We are already utilizing damaged bricks as brickbat Coba on the terrace.
9. Partial Replacement Of Quarry Dust
Bricks, tiles, and various light construction materials are obtained from quarry dust. In terms of chemical composition, quarry dust is similar to granite in many respects. Therefore, the strength and durability of quarry powder are suitable for use in concrete.
Concrete has a high compressive strength. If quarry dust is used in the concrete, the compressive strength will increase in a similar way.
We have already started utilizing quarry dust in our construction procedure, such as sand beds.
10. Plastic Waste Partial Replacement
According to E-Waste, plastic waste is similarly a considerable threat to humanity and the environment. Dumping them into the sea will excessively pollute the seawater, and plastic garbage will seriously pollute the environment.
Therefore, recycling plastic waste is a good way to deal with it in construction. When used in concrete, plastic must be clean and free of dust or various contaminants.
When using plastic waste, the workability of concrete is very good. Largely the plastic aggregates were utilized in road construction work. It is combined with asphalt to form a road.
Many projects have been implemented using this method.
11. Aggregate Properties Effect On Concrete
Concrete is a combination of cementitious material, aggregate, and water. The inert filling is generally considered as aggregates to aggregate containing 60-80% by volume and 70-85% by weight of concrete.
Although mixture is taken into consideration as an inert aggregate, it’s far an essential element that outlines concrete thermal and elastic properties and dimensional stability. when selecting a unit, the compressive strength of the unit is the crucial aspect.
Concrete is a combination of cementitious material, aggregate, and water. Inert filling is generally considered as aggregates to aggregate containing 60-80%by volume and70-85%by weight of concrete.
Although mixture is taken into consideration as an inert aggregate, it’s far an essential element that outlines concrete thermal and elastic properties and dimensional stability. When selecting a unit, the compressive strength of the unit is a crucial aspect.
In order to obtain a suitable mix ratio, various physical and mineral properties of the aggregate must be determined before mixing the concrete. Aggregate properties include the shape and texture, size gradation, specific gravity, water content, reactivity, soundness, and bulk unit weight. The aggregate properties together with the water/cementitious material ratio specify the workability, strength, and durability of the concrete.
The shape, as well as the texture of aggregate, affect the properties of just produced concrete better than hardened concrete. If smooth and round aggregates are used instead of rough, angular, or elongated aggregates, concrete will be more workable.
Extensively natural gravel and sands from seashores or riverbeds are soft and rounded and are outstanding aggregates. Broken down stone produces a lot of more angular and elongated aggregates, which possess a greater surface-to-volume ratio, adequate bond characteristics but need more cement paste to generate a workable mixture.
The aggregate covering texture can be either rough or smooth. A smooth surface can improve workability, and a rough surface will eventually form a strong bond between the paste and the aggregate, result in greater resistance.
Advantages Of The Replacement
- It is more
- More use of alternative aggregate its reduces Waste Material.
- Use of natural resources will be decreased.
- Economical products will be usable for construction.
Disadvantages Of The Replacement
- While using the alternative aggregate more material tests are required.
- When the replacement of aggregate in concrete structure strength may decrease.
- More maintenance work needed to enhance the life of the structure
Which material can we use to replace for coarse aggregates?
The Followings are the materials used for coarse aggregate replacement,
1. Fibrous concrete or papercrete an Eco-friendly alternative of aggregate in concrete.
2. Wastes of plastic as substitute of aggregates in concrete.
3. Glasscrete or Post-Consumer glass the sustainable alternative of aggregate in concrete.
4. Expanded Polystyrene Concrete: Lightweight alternative aggregate for concrete.
5. Crushed rubber as aggregates in concrete.
6. Coconut shell.
7. E-waste partial replacement.
8. Construction waste material.
9. Quarry dust for partial replacement.
10. Plastic waste partial replacement.
What are some examples of different types of materials that can be used as aggregates?
Usually used aggregate as a clinker, gravel, clay, ballast furnace ash, fly ash and sand.
How do you measure coarse aggregate quality?
we can measure quality of aggregate for different field test like sieve analysis , bulking of sand, fineness modulus, silt content and moisture content.
What is the difference between concrete and aggregate?
Concrete is basically mixture of sand, cement , water and aggregate. The aggregates are stone, crushed gravel ,rock and sand.
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