Eco-friendly Concrete Solutions Partial Replacement of Fine Aggregates with Copper Slag

Eco-friendly Concrete Solutions Partial Replacement of Fine Aggregates with Copper Slag, Sustainable Concrete Options Copper slag is used in place of some fine aggregates. One of the most common building materials utilized worldwide is concrete. Along with cement and water, aggregate is one of the main basic materials of concrete, accounting for between 55% and 80% of its volume. Coarse aggregates (particles larger than 4.75 mm) or fine aggregates (particles smaller than 4.75 mm) are the two types of aggregates that are utilized.

Either crushed large rocks or natural sources provide the aggregates required in concrete. While coarse aggregates are joined with cement paste during the hydration process, fine aggregates are employed to fill in the gaps between the coarse aggregate particles in cement concrete. Every year, the demand for natural aggregate consumption rises as a result of the global building sector, which accelerates the depletion of aggregate reserves.

The aggregates needed for concrete come from either natural sources or crushed big rocks. In cement concrete, fine aggregates are used to fill in the spaces between the coarse aggregate particles, while coarse aggregates are bonded with cement paste during the hydration process. The worldwide building sector accelerates the depletion of aggregate reserves, increasing the demand for natural aggregate consumption annually.

The extensive use of natural aggregates will devastate the environment. Therefore, in order to find substitutes for natural aggregates, it is essential to look into the potential of using waste materials and industrial by-products in the manufacturing of concrete. This will lead to sustainable concrete design and a greener environment.

Large volumes of industrial byproducts are produced annually by a range of industries. Finding ways to lessen the health hazards and disposal problems related to these wastes is the main goal of governments and environmental protection groups.

For a long time, fly ash, silica fume, and slag were considered waste products. In the construction industry, they have shown to be a successful substitute for Portland cement. Their role in increasing the durability of concrete is generally recognized, especially when compared to the use of Portland cement alone. Additionally, several companies are creating innovative byproducts that could eventually be utilized to partially substitute Portland cement.

Because concrete created with these ingredients is more workable and durable than ordinary concrete, it has been used to build power and chemical industries as well as underwater constructions. The use of some waste materials has been well documented in design requirements. Many enterprises are creating new waste materials and by-products, and the environment and human health may suffer if these materials are disposed of or dumped. As a result, the concrete industry offers numerous chances to recycle waste.

Slag

The term “SLAG” is broad. It includes all non-metallic byproducts that are produced when a metal is separated from its ore. The metal from which it is made and the method of solidification employed determine its morphological and chemical characteristics. Depending on the industry they originate from, they can be generically classified as ferrous (iron/steel) and nonferrous (copper, lead/zinc).

A general schematic representation of the lead-zinc, nickel, and copper slag production process is shown in the picture below. The types and applications of nonferrous slags, which make up just 12% of the entire yearly production, are detailed in Figure 1 below. The Production Process of Slag items made from ferrous slag, such as iron blast furnace slag (BFS). When iron ores are reduced to create molten iron and molten slag, this is the byproduct. 1.2.1. Air-cooled blast furnace slag is a light gray vesicular rock that forms when it is allowed to cool gradually to a crystalline rock form.Principle uses include

Uncrushed:- fill (especially in places that are heavily loaded, like mainline rail lines), working platforms on challenging sites, and pavements, where rolling breaks down the slag to fill in the spaces and creates binding fines.
Graded road base:- either by itself or in combination with other slags, natural rocks, and/or sands.
Crushed and graded:- for filter medium, glass insulation wool, concrete aggregates, concrete sand, and usage as a platform beneath concrete slabs. Granulated blast furnace slag is a glassy, sand-like substance that is created by subjecting the molten slag to high-volume, high-pressure water sprays. This product’s hue closely resembles that of typical beach sand.

(a) It is mostly used to replace cement (when ground), substituting between 30 and 50 percent of Portland cement in “normal” concrete. Still, it can replace as much as 70 percent in specialized applications like marine concrete.

(b) Other applications include producing glass, trace elements for agriculture, concrete blocks, drainage sub-base for sports fields, filtering media, reinforced earth embankments, mine backfilling, and grit-blasting medium that needs to be finely etched. Slag of copper, lead, and zinc (CLZS) It is typically granulated to create a sand-size product with a top size of roughly 5 mm and only a small amount of material below 1 mm. It is created when ores are smelted. It has earned the moniker “black sand” due to its dark hue. It is primarily spherical and has been utilized as sand for concrete.

Utilization of copper: Use and availability: One of the fundamental chemical elements is copper. Copper is a reddish-orange metal with strong electrical and thermal conductivity when it is almost pure. Numerous products, such as electrical wire, cooking pots and pans, pipes and tubes, car radiators, and many more, are frequently made using it. Additionally, copper is utilized as a pigment and preservative in wood, paint, paper, and textiles. It is mixed with tin to make bronze and with zinc to make brass. It is a ductile metal with high electrical conductivity that is widely used as a heat conductor, electrical conductor, building material, and alloy component.

Copper Slag

Copper slag is one of the industrial byproducts of the copper processing process. About 33 tons of slag are created globally at the moment, whereas three Indian copper companies—Hindustan Copper, Birla Copper, and Sterling produce roughly 6-6.5 tons of slag at different locations. Even though copper slag is widely used in the sandblasting industry and to make abrasive tools, it is thrown away without being recovered or used again.

Copper slag can be used in concrete as an aggregate substitute or as a partial replacement for Portland cement due to its mechanical and chemical characteristics. For example, copper slag has excellent stability, abrasion resistance, and soundness properties, among other beneficial mechanical properties for usage as aggregate.

Copper slag possesses pozzolanic properties because of its low CaO content and other oxides, such as Al2O3, SiO2, and Fe2O3. Using copper slag in the concrete industry as a replacement for cement and/or fine particles has two benefits: it lowers disposal costs and protects the environment (Figure 2). Many studies are still being conducted on the use of copper slag as a fine aggregate or as a partial replacement for ordinary Portland cement (OPC). Copper slag is also used in HSC, or high-strength concrete.

Properties of waste copper slag

Physical properties:-

The granules of copper slag have a fineness modulus of 3.5 and are black glassy in color. On a Moh’s scale, the hardness is typically about 7. The iron content will affect the specific gravity, which can range from 2.8 to 3.8. Compared to traditional aggregate, copper slag has a slightly higher unit weight.

Usually, the material absorbs very little (0.13 percent). Compared to air-cooled copper slag, granulated copper slag has a lower specific gravity and higher absorption because it is more porous. Regularly formed, angular particles, primarily ranging in size from 4.75 mm (3/4 in) to 0.075 mm (no. 200 sieve), comprise the granulated copper slag. The rapid cooling that causes copper slags to vitrify during slag formation keeps the molecules from being trapped in crystals.

Chemical properties:-

Blends of Portland cement with copper slag often have qualities that are comparable to those of Portland cement and fly ash. It might have pozzolanic qualities. It lowers the temperature of hydration. SiO2 (20–30%), Al2O3 (up to 8%), Fe2O3 (60–70%), and CaO (up to 5%), in general, are the main chemical components. Due to the excess of 70% in the proportions of iron, silica, and alumina oxide, this chemical composition aids in its pozzolanic action.

Effect of Copper Slag

It is suggested that substituting less than 40% copper slag for sand can produce high-strength concrete that is on par with or superior to the control mix; above this, the concrete’s microstructure develops more voids, microcracks, and capillary channels, which damages the concrete at an early strength level. The concrete’s workability and dynamic behavior can be enhanced by copper slag’s smooth, glassy surface texture, low moisture absorption, and exceptional compressibility. However, the compressive, flexural, and tensile splitting strengths are reduced by the increased fineness, the ferric oxide content, and the presence of excess water.

Advantages of using Copper slag as Fine Aggregate.

Because less waste is generated throughout the copper manufacturing process, using copper slag in place of FA benefits the environment.
Additionally, it helps preserve natural fine aggregate.
Solid hazardous and non-hazardous waste products should not be disposed of in landfills. Due of potential environmental consequences, this approach is not accountable. For the use or recycling of solid industrial waste materials, concrete is therefore a superior option.
By substituting more copper slag for fine aggregates, it improves workability.
The strength increased only slightly up to 40% or was about the same as the control mix.

Disadvantages of using copper slag as fine aggregates.

Copper slag’s characteristics can alter due to changes in its chemical makeup. Therefore, it’s crucial to evaluate chemicals before employing them.
The cohesiveness is negatively impacted by the glassy surface roughness of the copper slag particles.