Viability of Using High Amounts of Steel Slag Aggregates to Improve the Circularity and Performance of Asphalt Mixtures

Steel slag is a byproduct generated as waste during the steelmaking process and can be considered a cost-effective and environmentally acceptable alternative to replace natural aggregates. Using steel slag aggregates (SSA) to produce asphalt mixtures promotes sustainability and circular economy principles by using an industrial byproduct as a raw material. Thus, this work mainly aims to design more sustainable asphalt mixtures with high amounts of SSA that fit the circular economy expectations. This work developed two asphalt mixtures with SSA for surface (AC 14 surf) and binder/base (AC 20 bin/base) courses. Initially, the excellent wearing and polishing resistance of SSA and their good affinity with bitumen demonstrated the potential of this byproduct to be used in asphalt mixtures. Then, when analyzing the influence of using two different SSA incorporation rates (50% and a percentage close to 100%) in both asphalt mixtures, it was concluded that the use of SSA should be limited to 75% to avoid excessive air void contents and durability problems. The importance of considering the different particle densities of SSA and natural aggregates was highlighted during the mix design by defining a relationship between an effective and equivalent binder content. Finally, the mechanical performance of AC 14 and AC 20 with 75% SSA incorporation was compared to identical conventional mixtures produced with natural granite aggregates. The results obtained showed that the asphalt mixtures with 75% SSA have some workability problems due to the rough and porous surface of SSA. However, they present an excellent water sensitivity and permanent deformation resistance, surpassing the performance of the conventional asphalt mixtures.

Sustainable Materials Used as Lightweight Aggregate :(An Overview)

Lightweight aggregates (LWA) are building materials with a lower bulk density than standard construction aggregates. In recent years, the contribution of industry to the circular economy has become a serious concern. Among these, the mining sector is confronted with significant problems relating to the management of a huge quantity of generated waste. The major contemporary task is to address a number of interconnected challenges, including waste management and recycling, conservation of scarce natural resources, reduction of energy use, and reduction of greenhouse gas emissions. Natural aggregates are consumed by the construction materials industry in the range of 8 to 12 billion tons per year. According to reports, the construction materials sector consumes the most energy and scarce natural resources (rocks, aggregates, and water) while also emitting greenhouse gases. In general, using waste material as lightweight aggregate decreases the concrete’s overall weight. The materials used as lightweight aggregate in concrete are discussed in this study. According to research, utilizing trash as a lightweight aggregate not only improves the characteristics of concrete but also gives a sustainable approach to minimize global waste.

Eco-efficient steel slag concretes: an alternative to achieve circular economy

Annually billions of tonnes of aggregates are extracted to apply in civil construction generating environmental impacts and energy consumption. So, based on circular economy principles applying residues as aggregates is a good solution to reduce the mining activity and to generate a more efficient destination for the residues. Thus, this research aims to evaluate the technical, economic, and environmental performance of concretes produced entirely with steel slag aggregates. The concretes were characterized through physical properties, as specific gravity, water absorption, compressive and tensile strength. Durability tests (expansibility) were also conducted. The authors analyzed the cost assessment and environmental impact of steel slag concrete production as well. The incorporation of steel slag increases the compressive and tensile strength of concrete, analyzed in different ages. Additionally, the steel slag does not present expansibility when confined in the concrete matrix. The entire replacement of natural aggregates for steel slag allowed to reduce in 31% the cement consumption, a decrease of 140 kg/m3, for the same strength class. The environmental analysis showed that the incorporation of steel slag aggregates reduced the cement intensity of concrete and its impact. Regarding the cost assessment, the mixtures with steel slag presented a lower cost compared to the conventional one. These results indicate that steel slag aggregates could be used in a cleaner production of concrete, replacing natural aggregates with no injury. This research provides the feasibility of using steel slag aggregates in a cleaner and cheaper concrete production and contribute to the promotion of sustainable solutions for the construction sector through the circular economy principles.

Sustainable Management of Construction and Demolition Waste

Construction activity in India has magnified well within the past decade. Likewise, there has conjointly been a proportion to rise within the generation of construction and demolition waste (C&DW). This, alongside the fact that in India the speed of recycling and reuse of C&DW continues to be quite low and has engendered a heavy environmental downside and a motivation to develop ways and management plans to resolve it. Almost every time the construction and demolition waste end up settling in landfills disrupting the environmental, economic, and social life cycle. Its composition has a significant potential to reuse or recycle C&DW, and thereby, contribute to enhancing the sustainability of construction, however, practical procedures don’t seem to be widely known or practiced within the construction industry. Elements of construction and demolition waste generally embrace concrete, asphalt, wood, metals, roofing, paper, plastic, drywall, and glass. Sustainable development defines as accomplishing the current requirements without compromising the ability of future generations to satisfy their own needs and can be thought of as one of the concrete solutions to resolve construction and demolition waste downside. Sustainable development in construction can facilitate plenty to cut back the issues associated with the environment and natural resources as the construction industry is among the major user of the world’s resources. Sustainable design, correct use, and reuse of the resources/construction materials can create the construction industry a lot more economical and greener. There’s conjointly a large demand for natural aggregates within the construction sector with a big gap in its demand and supply, which may even be reduced marginally by the employment of recycling and reuse of construction and demolition waste. Correct handling, storage, and treatment of C&D waste not only solely forestall degradation of Mother Earth but even have an important impact on sustainability using reducing the usage of natural resources. The paper covers various issues associated with the reusing and recycling of C&D waste, which needs restrictive mechanisms and procedures to be followed for achieving the aim of sustainability in the construction industry.

Evaluation of the Volume Stability and Resource Benefit of Basic Oxygen Furnace Slag and Its Asphalt Mixture Based on Field Application

Applying basic oxygen furnace (BOF) slag as aggregate in asphalt mixture is continuously investigated due to the increasing shortage of natural aggregate in recent years. However, the negative effect of BOF’s expansion in water greatly limits its further application in pavement construction. To address this problem, this paper studied the volume stability of BOF, and its asphalt mixture relied on actual engineering. The asphalt mixtures contained BOF aggregate was designed by the Marshall method with three different gradation types (AC-16, AC-20, and ATB-25). Besides, both laboratory samples and the core samples from field drilling were investigated in volume expansion rate after curing in a water bath. The economic and resource benefits of BOF replacement of natural aggregates were also analyzed. The results showed that the free calcium oxide content of BOF slag is positively related to the particle sizes. Nevertheless, the expansion rates of both the BOF aggregate and its asphalt mixture were less than 1%, which meant the BOF aggregate applied to the asphalt mixture meets the practical engineering requirements. The maximum allowable free calcium oxide content for large-grain size of steel slag is the smallest; it is also recommended that the expansibility of large-grain steel slag should be the first concern in the application. The resource assessment indicated that the use of steel slag for the construction of a trial section of one kilometer of single lane can save 967 tons of natural aggregates. The economic evaluation showed that the use of steel slag instead of natural aggregates for surface course construction could reduce the investment by 16.87%. The experimental methods and conclusions mentioned in this article provide stable references to enhance the development of sustainable pavement by recycling metallurgical slag in highway construction.

Feasibility of recycling concrete construction waste in environmental and economic sides

n light of the conditions experienced by Syria and due to the destruction and demolition of its buildings built up rubble and occupied a large area of its territory. Therefore, it was necessary to develop an appropriate strategy to study these debris and provide the ideal solutions to be able to benefit from them as much as possible and thus mitigate the harmful impact on the environment and the surrounding environment. The work is divided into two parts: First: The study focuses on one of the mechanisms of benefiting from the recycled aggregate by using them in producing concrete, after studying their characteristics(Sieve Analysis-density- Absorption) and then mixing them with natural aggregate as replacement of natural coarse aggregate at different rates(15-30-45-75-100)%. Six concrete cubes were made for each mixture and 3 cubes were broken after 7 days and the other after 28 days . it was concluded The relationship between the percentage of recycled aggregates and compressive strength, as well as the relationship between the percentage of stones and the rate of Absorption The results showed that the acceptable percentage of replacement of natural aggregates with recycled aggregates may reach 100% with the recording of values of resistance of up to 21.9Mpa . Second :The environmental and economic feasibility of using recycled aggregates has been studied the results showed that use 75% of the recycled aggregates in structural concrete works will reduce energy consumption and carbon dioxide emissions by 28% and 33%, respectively, and the economic saving rate is 63.71%. . Through this study two objectives can be achieved: First: removing large quantities of environmental pollution sources resulting from these wastes and thus achieving an environmental goal. Second: Provide other sources of concrete aggregates and thus protect the natural quarries and achieve an economic goal.

Experimental Investigation on Strength and Behavior of PSC Fiber Reinforced Beams with GGBS

The Concrete is one of the most important products which are efficiently and effectively used in the field of construction. The usage of natural aggregates in the process of production of concrete was high which lead to huge deficiency of availability of the natural aggregates. At the same time production of cements leads to more environmental pollution. Therefore, the production of concrete was altered by vast usage of admixtures and replacements for natural aggregates. In this paper M60 grade concrete is prepared by using GGBS as a partial replacement of cement which is a good strength building mineral admixture, the steel fibers were also introduced in the concrete to improve the strength parameter and for ease of work with concrete and addition of AUROMIX – 400 which is provided by FOSROC chemicals Bengaluru as super plasticizers. The concrete specimens like Cubes and Cylinders were casted and allowed to curing over a nominal curing period of 7, 14 and 28 days to know the basic mechanical properties of the concrete with the above replacements and at the same time RCC beams were also casted and cured, then post tensioned to know the flexural details of this special concrete.

Recycled Refractory Brick as Aggregate for Eco-friendly Concrete Production

The amount of construction and demolition waste continues to increase year by year.These wastes have a significant harmful influence on the environment; refractory brick is among of these wastes. this paper concerns the reuse of refractory brick wastes to produce an eco-friendly concrete. To achieve this objective,coarse and fine Natural Aggregates (NA) were partially replaced with recycled Refractory Brick Aggregates (RBA). According to the design of experiment, two families of mixes were prepared and tested: the first mixes was made with coarse and fine NA (as reference concrete) and the second mixes made by replacing 20% of coarse and fine NA by coarse and fine RBA. For each of the mentioned families, three cement dosages of 350 kg/m3 , 400 kg/m3 , 450 kg/m3 were investigated. A series of experiments including water porosity, density, Ultrasonic Pulse Velocity (UPV) and compressive strength were assessed. Observed results indicate that the use of coarse and fine RBA had a relatively influence on the water porosity and UPV of concrete. However, the use of coarse and fine RBA produces a slightly decreased the density of concrete (below 2%). Moreover, the use of coarse and fine RBA in concrete improved the compressive strength. Hence, coarse and fine RBA can be successfully used to produce concrete with acceptable properties.

Ground Waste Tire Rubber as a Total Replacement of Natural Aggregates in Concrete Mixes: Application for Lightweight Paving Blocks

The use of waste materials as alternative aggregates in cementitious mixtures is one of the most investigated practices to enhance eco-sustainability in the civil and construction sectors. For specific applications, these secondary raw materials can ensure adequate technological performance, minimizing the exploitation of natural resources and encouraging the circular disposal of industrial or municipal waste. Aiming to design and develop lightweight paving blocks for pedestrian or very light-traffic purposes (parking area, garage, sidewalk, or sports surfaces), this paper presents the material characterization of rubberized cement mortars using ground waste tire rubber (0–1 mm rubber powder and 1–3 mm rubber granules) to totally replace the mineral aggregates. Considering recommended requirements for concrete paving members in terms of mechanical strength, water drainage performance, acoustic attenuation, and dynamic and energy absorption behavior, a comprehensive laboratory testing is proposed for five different formulations varying the sand-rubber replacement level and the proportion ratio between the two rubber fractions. Tests highlighted positive and promising results to convert laboratory samples into pre-cast members. The “hot” finding of the work was to prove the feasibility of obtaining totally rubberized mortars (0 v/v% of sand) with suitable engineering performance and enhanced eco-friendly features.