Rudolph N. Kraus

Bio: Rudolph N. Kraus is an academic researcher from University of Wisconsin–Milwaukee. The author has contributed to research in topics: Fly ash & Cement. The author has an hindex of 14, co-authored 63 publications receiving 641 citations.

Properties of Field Manufactured Cast-Concrete Products Utilizing Recycled Materials

Abstract: This investigation was performed to develop technology for manufacturing cast-concrete products using Class F fly ash, coal-combustion bottom ash, and used foundry sand. A total of 18 mixture proportions with and without the by-products was developed for manufacture of bricks, blocks, and paving stones. Replacement rates, by mass, for sand with either bottom ash or used foundry sand were 25 and 35%. Replacement rates, by mass, for portland cement with fly ash were 25 and 35% for bricks and blocks, and 15 and 25% for paving stones. Analysis of test data revealed that bricks with up to 25% replacement of cement and blocks with up to 25% replacement of cement and sand with recycled materials are suitable for use in both cold and warm climates. Other bricks and blocks were appropriate for building interior walls in cold regions and both interior and exterior walls in warm regions. Paving stones with 15% replacement of cement with fly ash showed higher strength, freezing and thawing resistance, and abrasion resistance than the control specimens.

Precast concrete products using industrial by-products

Abstract: This work aimed to help establish the use of high volumes of fly ash, bottom ash, and used foundry sand in manufacture of precast molded concrete products such as wet-cast concrete bricks and paving stones. ASTM Class F fly ash was used as a partial replacement for 0 (reference), 25, and 35% of portland cement. Bottom ash combined with used foundry sand replaced 0, 50, and 70% of natural sand. Tests for compressive strength, freeze-thaw resistance, drying shrinkage, and abrasion resistance were conducted on the wet-cast concrete masonry units manufactured at a commercial manufacturing plant. It was concluded that all wet-cast bricks could be used for both exterior and interior walls in regions where freezing and thawing is not a concern, and for interior walls in regions where freezing and thawing is a concern. No wet-cast paving-stone mixtures, including the reference mixture, met all ASTM requirements for paving stones.

Long-term performance of high-volume fly ash concrete-pavements

Abstract: This investigation was undertaken to evaluate the long-term performance of concrete pavements made with high volumes of Class F and Class C fly ash (FA). Six different mixtures, three mixtures with Class C fly ash up to 70% cement replacement and three mixtures with Class F fly ash up to 60% cement replacement, were used. Long-term performance tests were conducted for compressive strength, resistance to chloride-ion penetration, and density using specimens from in-situ pavements. Long-term results showed greater pozzolanic strength contribution of Class F fly ash relative to Class C fly ash. Generally, based upon long-term data, mixtures containing Class F fly ash exhibited higher resistance to chloride-ion penetration relative to mixtures containing Class C fly ash. Compressive strengths of core specimens taken from in-situ pavements ranged from 45 to 57 MPa (6,600 to 8,300 psi) at seven to 14 years of age. The highest long-term compressive strength (57 MPa, 8,300 psi) was achieved for the high-volume fly ash mixture incorporating 67% Class F fly ash at the age of 7 years. Visual observations (in 2000) revealed that the pavement sections containing high volumes of Class F fly ash (40 to 67% FA) performed well in the field with only minor surface scaling. All other pavement sections have experienced very little surface damage due to the scaling.

Long-Term Performance of High-Volume Fly Ash Concrete Pavements

Abstract: This study was conducted to evaluate the long-term performance of concrete pavements made with high volumes of Class F or C fly ash. Six different mixtures--3 with Class C fly ash with up to 70% cement replacement and 3 mixtures with Class F fly ash with up to 67% cement replacement--were used. Long-term performance tests for all mixtures were performed for compressive strength, resistance to chloride-ion penetration, and density using core specimens from in-place pavements. Results revealed a greater pozzolanic strength contribution of Class F fly ash relative to Class C fly ash. Generally, concrete mixtures containing Class F fly ash exhibited higher resistance to chloride-ion penetration relative to mixtures containing Class C fly ash. Other findings and observations are discussed.

The greening of the concrete industry

Abstract: The concrete industry is known to leave an enormous environmental footprint on Planet Earth. First, there are the sheer volumes of material needed to produce the billions of tons of concrete worldwide each year. Then there are the CO2 emissions caused during the production of Portland cement. Together with the energy requirements, water consumption and generation of construction and demolition waste, these factors contribute to the general appearance that concrete is not particularly environmentally friendly or compatible with the demands of sustainable development. This paper summarizes recent developments to improve the situation. Foremost is the increasing use of cementitious materials that can serve as partial substitutes for Portland cement, in particular those materials that are by-products of industrial processes, such as fly ash and ground granulated blast furnace slag. But also the substitution of various recycled materials for aggregate has made significant progress worldwide, thereby reducing the need to quarry virgin aggregates. The most important ones among these are recycled concrete aggregate, post-consumer glass, scrap tires, plastics, and by-products of the paper and other industries.

나의 Concrete 연구실

Abstract: This chapter describes the methodology used in EPA’s Waste Reduction Model (WARM) to estimate streamlined life-cycle greenhouse gas (GHG) emission factors for concrete beginning at the point of waste generation. The WARM GHG emission factors are used to compare the net emissions associated with concrete in the following two waste management alternatives: recycling and landfilling. Exhibit 1 shows the general outline of materials management pathways for concrete in WARM. For background information on the general purpose and function of WARM emission factors, see the Introduction & Overview chapter. For more information on Recycling and Landfilling, see the chapters devoted to these processes. WARM also allows users to calculate results in terms of energy, rather than GHGs. The energy results are calculated using the same methodology described here but with slight adjustments, as explained in the Energy Impacts chapter.

High performance, high-volume fly ash concrete for sustainable development

Abstract: This paper presents a brief review of the theory and construction practice with concrete mixtures that contain more than 50% fly ash by mass of the cementitious material. The mechanisms by which the incorporation of high volume of the ash in concrete reduces the water demand, improves the workability, minimizes cracking due to thermal and drying shrinkage, and enhances durability to reinforcement corrosion, sulfate attack, and alkalile-silica expansion are discussed. This technology can play a huge role in meeting the large demand for infrastructure in a sustainable manner for countries like China and India.

Sustainability of Concrete Construction

Abstract: Sustainability is important to the well-being of our planet, continued growth of a society, and human development. Concrete is one of the most widely used construction materials in the world. However, the production of portland cement, an essential constituent of concrete, leads to the release of significant amounts of CO2, a greenhouse gas GHG; production of one ton of portland cement produces about one ton of CO2 and other GHGs. The environmental issues associated with GHGs, in addition to natural resources issues, will play a leading role in the sustainable development of the cement and concrete industry during this century. For example, as the supply of good-quality limestone to produce cement decreases, producing adequate amounts of portland cement for construction will become more difficult. There is a possibility that when there is no more good-quality limestone in, say, a geographical region, and thus no portland cement, all the employment associated with the concrete industry, as well as new construction projects, will be terminated. Because of limited natural resources, concern over GHGs, or, both, cement production is being curtailed, or at least cannot be increased to keep up with the population increase, in some regions of the world. It is therefore necessary to look for sustainable solutions for future concrete construction. A sustainable concrete structure is constructed to ensure that the total environmental impact during its life cycle, including its use, will be minimal. Sustainable concrete should have a very low inherent energy requirement, be produced with little waste, be made from some of the most plentiful resources on earth, produce durable structures, have a very high thermal mass, and be made with recycled materials. Sustainable constructions have a small impact on the environment. They use "green" materials, which have low energy costs, high durability, low maintenance requirements, and contain a large proportion of recycled or recyclable materials. Green materials also use less energy and resources and can lead to high-performance cements and concrete. Concrete must keep evolving to satisfy the increasing demands of all its users. Designing for sustainability means accounting for the short-term and long-term environmental consequences in the design.