Production and Evaluation of Synthetic Lightweight Aggregates Based on Mixture of Fluidized Bed Fly Ash and Post-Mining Residues

This paper presents an attempt to obtain technically valuable lightweight aggregate produced from a mixture of fluidized bed fly ash and post-mining residues. The motivation to take up this study is a problem with the reasonable utilization of huge amounts of ashes produced by power plants in Poland. The ashes still produced and those stored in heaps amount to a tonnage of millions, and new ways to utilize them are desired. A real lack of mineral aggregates (non-renewable resources) demands the search for alternative materials. Using the industrial ashes as aggregates is a possible solution to the two above-mentioned problems. The aim of the study was to produce the lightweight aggregate components and to assess them in terms of their physical and mechanical properties. The components were prepared by mixing, granulation, and sintering at the temperature of over 1170 °C. Evaluation of physical parameters was based on parameters such as bulk density and water absorption. The study of mechanical properties was carried out on the basis of aggregates’ resistance to crushing. The obtained results revealed that using a mixture of the combustion and post-mining residues in the production of a lightweight aggregate is beneficial and results in the formation of a porous and durable structure. The measured resistance to the crushing of the produced aggregates varied from 5.9 MPa to 7.5 MPa. They also showed a high freeze-thaw resistance and good resistance to aggressive environments (bases, acids, salt). The registered properties indicate that the aggregates meet the basic requirements for materials used in construction and road-building. This study has a scientific and didactic value in that it describes the step-by-step process of planning and implementing the production of synthetic mineral aggregates.

Resistance under Marshall monotonic load for asphalt concrete mixtures

The dense hot MDC-19 type asphalt mixes are considered, by the “Instituto Nacional de Vías” in Colombia, as continuous grading asphalt mixes (asphalt concrete). These constitute most of the surface course, in the structures of in-service pavements, being the object of study and research in different projects to ensure their durability. In the present investigation, unlike other investigations, the mechanical behavior under Marshall monotonic load was studied in the laboratory between MDC-19 dense type asphalt mixtures, comparing plant-produced and laboratory-produced asphalt mixtures. To carry out this process, samples of uncompacted asphalt mixtures were taken, produced in four fixed plants, with which Marshall-type briquettes were compacted. Likewise, samples of mineral aggregates and asphalt cement were obtained from the same plants, which constitute the mixtures raw material produced there. With these materials, briquettes with the same characteristics were mixed and compacted. Subsequently, the resistance under Marshall monotonic load was determined on the briquettes manufactured in plant and laboratory. The optimal asphalt cement content was compared between plant and laboratory- produced mixtures. An increase in Marshall Stability was found in the briquettes made with plant-produced mixtures, while these required a greater amount of asphalt cement for their production.

METASOMATIC CHANGES IN ROCKS OF SEDIMENTARY COMPLEXES IN THE CARPATHIAN OIL AND GAS PROVINCE AS AN INDICATOR OF CARBOHYDRATE MIGRATION

A field and laboratory investigation of sedimentary rocks in Carpathian oil and gas province was curried out. The theoretical and practical aspects of the peculiarities of the development of metasomatic process during the migration of fluids at the postsedimentation stage of rock formation were investigated. Based on detailed field researches, a consistent pattern of mineral aggregates’ and their crystalloid individuals developing was defined. The arguments for developing a new geochemical model of oil deposits indication in Carpathian oil and gas province were provided.

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.

On the Adsorption Mechanism of Humic Substances on Kaolinite and Their Microscopic Structure

Soil organic matter (SOM) and various inorganic minerals represent key components of soils. During pedogenesis and due to biological activity these species interact, having a crucial impact on the formation of an aggregated soil structure with a hierarchical arrangement from nano to macro scale. In this process, the formation of organo–mineral microaggregates represents a dominant factor affecting soil functions and properties. This study focuses on the interactions between humic substances (HSs) and the mineral kaolinite as typical representatives of SOM and soil minerals. By performing classical molecular dynamics (MD) simulations on models of HSs and kaolinite, we demonstrate how two dominant but chemically different kaolinite surfaces affect the stability of HSs microaggregates. By analyzing volumetric, structural, and energetic properties of SOM–kaolinite models, we explain possible mechanisms of the formation of stable SOM–clay aggregates and show how a polarized environment affects the electrostatic interactions, stabilizing the microscopic structure of SOM–mineral aggregates. Our results showed that when stable aggregates of HSs are confined in kaolinite nanopores, their interactions with kaolinite surfaces disintegrate them into smaller subaggregates. These subaggregates are adsorbed more strongly on the polar aluminol surface of kaolinite compared to less the active hydrophobic siloxane surface.

Study on Tyre Rubber Modified Bitumens Mix for Road Asphalt Mixtures

In this study the strength & stability characteristics of bituminous mix for 80/100 grade bitumen is to studied and the effect of waste crumb rubber strength and stability characteristics in Bituminous mix and rubber bituminous mix is analyzed. Keywords: voids in mineral aggregates (VMA), voids filled with bitumen (VFB) Method, Crumb rubber, Crumb rubber bituminous mix, stability, flow, Bulk Density

Wear and Fragmentation Resistance of Mineral Aggregates—A Review of Micro-Deval and Los Angeles Tests

The aim of this article is to present the current knowledge and experiences related to wear and fragmentation resistance tests and to indicate those of their aspects that require further research. For this purpose, a review of the literature was performed. Results show that tests of resistance to wear (the MDE/DS test) and fragmentation (the LA test) are performed worldwide according to different standards (and thus following different test methods), which prevents a comparison of the obtained results. Comparative research into the MDE/DS and LA tests indicates that the MDE/DS test is more effective. The disadvantage of both tests lies in the dimension range of the aggregate. In addition, the use of steel balls in the LA test may not reflect the actual influence that the internal properties of the material have on the fragmentation process. A final review of the available knowledge allowed the formulation of proposals regarding further research directions, such as proposed changes of test methods, extensive analysis, and selection of optimal dimensions for tested aggregates, analysis of short-term and long-term tests, as well as extensive research into and an analysis of the impact of crushing on the physical, mechanical, and geometric properties of aggregates.

Sunflower Stalks versus Corn Cobs as Raw Materials for Sustainable Concrete

Concrete, the most common material in the building industry, involves the use of mineral aggregates that represent an exhaustible resource, despite their large availability. For a series of applications, these mineral aggregates can be replaced by vegetal ones, which represent an easy renewable natural resource. In this study, two types of vegetal raw materials, namely sunflower stalks and corn cobs, were used in developing 10 compositions of ecological microconcrete, with different percentages involved: 20%, 35%, 50%, 65% and 80%; they were analyzed from the perspectives of density, compressive strength, splitting tensile strength, resistance to repeated freeze-thaw cycles, modulus of elasticity and thermal conductivity. The results revealed that the microconcretes with sunflower stalks registered slightly higher densities and better results regarding the compressive strength, splitting tensile strength, modulus of elasticity, and freeze-thaw resistance than those with corn cobs. Lightweight concrete is obtained when more than 50% replacement rates of the mineral aggregates are used.