INFLUENCE OF QUARTZ SAND AND MARBLE-SLUDGE POWDER AS REPLACEMENTS FOR FINE AGGREGATE ON THE MECHANICAL PROPERTIES OF HIGH-STRENGTH SELF-COMPACTING CONCRETE

High-strength self-compacting concrete (HSSCC) is widely used as an eco-effective structure that is more durable than traditional cement that is more prone to demolitions and damage. One of today’s notable innovations is self-compacting concrete (SCC). The variety of materials and the utilization of siphons encourage the concrete’s use, which is significant. The worries about complex pieces are understandable due to the ease, with which precarious projecting zones are formed. This article presents high-strength self-compacting concrete, including quartz sand (QS) and marble-sludge powder (MSP) used as a partial replacement of fine aggregate (M sand). The substitution impact of QS and MSP on the strength of HSSCC is investigated. Further, V-funnel, L-box, slump flow, J-ring and slump cone are used to investigate the chemical, physical and mechanical properties such as splitting tensile strength, compressive strength, bond strength and flexural strength. The replacement of fine aggregate with 15 % of marble-sludge powder and 45 % of quartz sand (HSSCC concrete) gives an unprecedented outcome in the form of solidity and consistency. The findings show that the HSSCC 9 mix exhibits the compressive strength, splitting tensile strength, flexural strength and, more noteworthy, bond strength of 82.25 MPa, 8.10 MPa, 27.10 MPa and 11.89 MPa, respectively.

A multifunctional plant for a sustainable reuse of marble waste toward circular economy

The marble processing cycle involves the production of large quantities of wastes whose disposal represents an economic and environmental concern for marble companies due to the difficulty of identifying suitable landfills and the high transfer costs. In this context, the design of a sustainable industrial plant that allows the reuse of the calcium carbonate (CaCO3) contained in the marble waste is extremely challenging. With this recognition, the main industrial applications of CaCO3 are firstly analyzed in the present work to identify the physical–chemical properties required to CaCO3 in these contexts. Later, different plant solutions are suggested to recover CaCO3 from marble sludge in order to allow its use in industrial applications. The designed industrial plant includes an energy efficient drying phase, which exploits the thermal waste of the exhaust gases produced in a cogeneration section, and a subsequent milling phase. Since marble wastes currently constitute an economic burden for companies and an environmental emergency for the Public Administration, the performed technical–economic analysis shows that its recovery may represent an opportunity of sustainable development for the marble sector.

Valorization of Powder Obtained from Marble Sludge Waste and Its Suitability as a Mineral Filler

Stone industry has generated about 200 million tons of marble waste by marble processing industries whether in the form of sludge or solid blocks. The accumulated marble wastes contaminate water and air and have harmful effects on human health, plants, and animals. This study focuses on exploring the uses of powder obtained by drying and grinding marble sludge waste, generated from marble manufacturing processes, as a mineral filler for other construction materials. First, physical characterization was performed on marble sludge. Second, the powder preparation process was presented. Thereafter, a set of tests was carried out to identify the chemical, mineralogical, and physical properties of marble powder. By doing so, tests such as chemical analysis, calcium carbonate content, and methylene blue test, as well as mineralogical characterization using X-ray diffraction (XRD), Atterberg limits, particle size analysis, densities, Blaine specific surface, hydraulic property, as well as reaction with admixture, cement, and activity index were conducted. In the last part of this work, the obtained powder properties are compared to the standards requirements to confirm its suitability as mineral filler. The test results showed that the obtained marble powder is too rich in calcite; it is poor of any clay minerals fraction; it is very well graded; it is not reactive; and it does not have any effects on concrete strength; consequently, it can be considered as a mineral filler.

SYNERGISTIC EFFECT OF SUGARCANE BAGASSE ASH AND MARBLE SLUDGE POWDER AS A PARTIAL REPLACEMENT OF CEMENT IN CONCRETE

Marble sludge powder is produced as a by-product during the cutting and polishing of marble. Similarly, sugarcane bagasse ash is produced during the burning operation of sugarcane bagasse. Improper disposal of these waste materials poses a severe threat to the environment. The objective of this research study was to partially substitute cement with a binary mixture of SBA and MSP to reduce the environmental and health issues by adequately utilizing the waste material in the production of low-cost and eco-friendly concrete. For this purpose, a total of 174 concrete cylinders were tested. Apart from this, XRF and EDX tests were performed to determine the chemical composition of waste. Ordinary Portland cement was replaced with a binary mix of SBA and MSP from 0 to 40% by weight to achieve the synergistic effect. Various tests were performed, including compressive and splitting tensile strength and material tests, i.e. specific gravity, absorption capacity, sieve analysis, dry rodded unit weight, and moisture content. The tested specimens were compared with the control samples. The results showed that the difference between compressive and tensile strength up to 15% replacement is within targeted strength and slump. The optimized sample by partial substitution with a negligible effect on properties of concrete was SB10-MP5 and SB5-MP10. The increase in partial replacement above 15% will lead to a decrease in compressive and tensile strength. The cost per cubic meter of concrete was reduced by 8% as per MRS2019.

Reduction of Marble Waste Landfills through the Enhancement of CaCO3

The purpose of this research is to show how to reduce the amount of landfilled marble waste/scraps by collecting and re-purposing the marble microfine sawdust, which is produced after the sawing and processing of carbonate dimension stones. Our ultimate goal is to identify alternative uses, rather than landfilling. The current solution so far preferred - landfill - does not fully meet sustainable development criteria. Our reduction strategy is based on a regulatory framework which identifies waste, by-product and end of waste status clearer. After a careful characterization, the marble sawdust can be reused and marketed for industrial applications, that employ micronized calcium carbonate, as a new material. During the first few years of study, the research focused on the construction industry (i.e. concrete – plaster - brick), by assessing the extensive use of marble sludge. The building industry is able to incorporate and reuse waste materials deriving from different industries, although, in this way, such material would be regarded as of poor quality. The current trend is to add high economic value to this waste. Since product specifications for calcium carbonate vary depending on its application, a comparison with the paper - rubber - and tyre calcium carbonate requirements is described herein and, in addition, the final results of the tests carried out on marble sawdust in tyre mixtures are also reported in detail.