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A sustainable use of locally available wastes from agriculture as supplementary cementitious materials (SCMs) is an alternative solution for the prevention of excessive raw material usage, reduction of CO2 emission and cost-effective concrete production. This paper studies the reactivity of non-traditional waste SCMs: Wheat straw ash (WSA), mixture of wheat and soybean straw ash (WSSA) and soybean straw ash (SSA), which are abundant as agricultural by-products in Serbia. The chemical evaluation using XRF technique, thermal analysis (TGA/DSC), XRD and FTIR methods were performed along with physical properties tests to investigate the feasibility of utilizing biomass ashes as cement substitutes. The obtained results demonstrate a high pozzolanic activity of WSA, which is attributed to a high reactive silica content of the ash and its satisfactory level of fineness. A wider hump in XRD pattern of WSA compared to WSSA and SSA confirmed that it abounds in amorphous (reactive) phase. The insufficient activity index of soybean-based biomass ashes, characterized with a low silica content, was improved by additional grinding and/or blending with amorphous silica-rich material. This points out the mechanical activation, i.e., grinding procedure, and chemical activation, i.e., modification of the chemical composition, as techniques efficient at producing pozzolanic materials from biomass wastes. Tested biomass ashes are characterized with negligible leaching values of heavy metals, thereby satisfying eco-friendly principles of SCM utilization. The application of biomass ashes as SCMs leads to substantial cost savings, as well as benefits to the environment, such as lower consumption of cement, reduction of CO2 emissions during the production of cement and sustainable waste management.
Slobodan Šupić; Mirjana Malešev; Vlastimir Radonjanin; Vesna Bulatović; Tiana Milović. Reactivity and Pozzolanic Properties of Biomass Ashes Generated by Wheat and Soybean Straw Combustion. Materials 2021, 14, 1004 .
AMA StyleSlobodan Šupić, Mirjana Malešev, Vlastimir Radonjanin, Vesna Bulatović, Tiana Milović. Reactivity and Pozzolanic Properties of Biomass Ashes Generated by Wheat and Soybean Straw Combustion. Materials. 2021; 14 (4):1004.
Chicago/Turabian StyleSlobodan Šupić; Mirjana Malešev; Vlastimir Radonjanin; Vesna Bulatović; Tiana Milović. 2021. "Reactivity and Pozzolanic Properties of Biomass Ashes Generated by Wheat and Soybean Straw Combustion." Materials 14, no. 4: 1004.
The aim of the research presented in this paper is the experimental confirmation of the numerically defined shapes of the Strut-and-Tie models, designed according to the EN 1992-1-1 recommendations, and obtained from the software “ST method”. Three reinforced concrete deep beams with openings were tested. Each of them had the same dimensions and quality of the material characteristics. The specimens, constructed as simply supported beams, were loaded with two concentrated forces and were tested for bending until failure. Each specimen was reinforced with different reinforcement layout determined by variation parameter β, incorporated in the software “ST method”. For the determination of the Strut-and-Tie models, all of the reinforcement layouts were equally favored in the first specimen (β = 1.0 for 0°, 45°, and 90°), only the horizontal direction was favored in the second (β = 1.0 for 0°), while in the third specimen the one at the angle of 45° (β = 1.0 for 45°). Based on the results of experimental research, it was concluded that the behavior of loaded members was in agreement with the proposed shapes of the Strut-and-Tie models that were used for their design, and it was confirmed that the program “ST method” can be used for obtaining Strut–and-Tie models.
Anka Starčev-Ćurčin; Andrija Rašeta; Mirjana Malešev; Danijel Kukaras; Vlastimir Radonjanin; Miloš Šešlija; Drago Žarković. Experimental Testing of Reinforced Concrete Deep Beams Designed by Strut-And-Tie Method. Applied Sciences 2020, 10, 6217 .
AMA StyleAnka Starčev-Ćurčin, Andrija Rašeta, Mirjana Malešev, Danijel Kukaras, Vlastimir Radonjanin, Miloš Šešlija, Drago Žarković. Experimental Testing of Reinforced Concrete Deep Beams Designed by Strut-And-Tie Method. Applied Sciences. 2020; 10 (18):6217.
Chicago/Turabian StyleAnka Starčev-Ćurčin; Andrija Rašeta; Mirjana Malešev; Danijel Kukaras; Vlastimir Radonjanin; Miloš Šešlija; Drago Žarković. 2020. "Experimental Testing of Reinforced Concrete Deep Beams Designed by Strut-And-Tie Method." Applied Sciences 10, no. 18: 6217.
This paper presents results regarding the phase composition, microstructure and textural properties of two types of aggregates, which were prepared via crushing or pelletization of alkali-activated Class F fly ash and cured under different conditions. The alkali activator was the same for aggregate products, containing an alkaline solution consisting of 8 M NaOH and Na-silicate (8 M NaOH/Na-silicate = 1:2.5 mass ratio). The aforementioned properties were influenced by two different preparation procedures combined with varying curing regimes (under normal conditions at 20 °C, RH 40⁻60% for 28 and 120 days and under an accelerated regime, at 65 °C for 5 days). Aggregates were characterized using X-ray diffraction (XRD), Fourier-transform transmission infrared spectroscopy (FTIR), back scattered electron microscopy with energy dispersive spectrometer (BSE-EDS) analyses and mercury intrusion porosimetry (MIP). The results showed noteworthy structural and textural diversities between the two types of aggregate. The method of preparation and curing regime affected the formation of the N-A-S-H structure and the texture of the alkali-activated fly ash product, with the crushing method giving an advantage.
Ognjen Rudić; Vilma Ducman; Mirjana Malešev; Vlastimir Radonjanin; Suzana Draganić; Slobodan Šupić; Miroslava Radeka. Aggregates Obtained by Alkali Activation of Fly Ash: The Effect of Granulation, Pelletization Methods and Curing Regimes. Materials 2019, 12, 776 .
AMA StyleOgnjen Rudić, Vilma Ducman, Mirjana Malešev, Vlastimir Radonjanin, Suzana Draganić, Slobodan Šupić, Miroslava Radeka. Aggregates Obtained by Alkali Activation of Fly Ash: The Effect of Granulation, Pelletization Methods and Curing Regimes. Materials. 2019; 12 (5):776.
Chicago/Turabian StyleOgnjen Rudić; Vilma Ducman; Mirjana Malešev; Vlastimir Radonjanin; Suzana Draganić; Slobodan Šupić; Miroslava Radeka. 2019. "Aggregates Obtained by Alkali Activation of Fly Ash: The Effect of Granulation, Pelletization Methods and Curing Regimes." Materials 12, no. 5: 776.
This paper presents the results of experimental research on the effect of the lightweight aggregate, type and amount of cement on the values of the modulus of elasticity of lightweight aggregate concrete. Six different concrete mixtures were made to test if it is possible to replace recommended Portland cement with Portland composite cement, or to reduce the amount of cement and to obtain a satisfactory performance of the lightweight aggregate concrete. Values of the static and dynamic modulus of elasticity determined experimentally were analysed and then compared with the values obtained by FIP recommendation. In addition, for the five types of concrete, stress–strain (σ–ε) curves were determined and analysed. It was concluded that there is a very good correlation between static and dynamic modulus of elasticity and very good match between the experimental and empirical results. The analysis of the values of σ–ε curves led to the conclusion that type of cement does not significantly affect analysed properties, while the effect of the amount of cement cannot be neglected.
Mirjana Malešev; Vlastimir Radonjanin; Ivan Lukić; Vesna Bulatović. The Effect of Aggregate, Type and Quantity of Cement on Modulus of Elasticity of Lightweight Aggregate Concrete. Arabian Journal for Science and Engineering 2013, 39, 705 -711.
AMA StyleMirjana Malešev, Vlastimir Radonjanin, Ivan Lukić, Vesna Bulatović. The Effect of Aggregate, Type and Quantity of Cement on Modulus of Elasticity of Lightweight Aggregate Concrete. Arabian Journal for Science and Engineering. 2013; 39 (2):705-711.
Chicago/Turabian StyleMirjana Malešev; Vlastimir Radonjanin; Ivan Lukić; Vesna Bulatović. 2013. "The Effect of Aggregate, Type and Quantity of Cement on Modulus of Elasticity of Lightweight Aggregate Concrete." Arabian Journal for Science and Engineering 39, no. 2: 705-711.
The paper presents results of experimental investigation of concrete made with recycled concrete aggregate, low cement content and high content of different mineral supplements. Such concretes belong to “green” or “eco” concretes, since they have less impact on the environment, help in solving the problem of construction and industrial waste disposal, and contribute to the conservation of natural resources. For green recycled aggregate concrete (GRAC) production fine river aggregate and coarse recycled aggregate were used and 50% of cement by weight was replaced by a variety of inert, pozzolanic, and highly reactive mineral admixtures: milled limestone, fly ash, silica fume and metakaolin. Basic properties of ten different concrete mixtures were tested, compared and classified in terms of possible applications. Test results showed that the optimal combination of different mineral admixtures can reduce the basic disadvantage of concrete with high content of mineral supplements – the relatively low strength in the period up to 28-day age, which allows certain structural applications of this type of “green” concrete.
Vlastimir Radonjanin; Mirjana Malešev; Snežana Marinković; Ali Emhemd Saed Al Malty. Green recycled aggregate concrete. Construction and Building Materials 2013, 47, 1503 -1511.
AMA StyleVlastimir Radonjanin, Mirjana Malešev, Snežana Marinković, Ali Emhemd Saed Al Malty. Green recycled aggregate concrete. Construction and Building Materials. 2013; 47 ():1503-1511.
Chicago/Turabian StyleVlastimir Radonjanin; Mirjana Malešev; Snežana Marinković; Ali Emhemd Saed Al Malty. 2013. "Green recycled aggregate concrete." Construction and Building Materials 47, no. : 1503-1511.
A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate). Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC) had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.
Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability 2010, 2, 1204 -1225.
AMA StyleMirjana Malešev, Vlastimir Radonjanin, Snežana Marinković. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability. 2010; 2 (5):1204-1225.
Chicago/Turabian StyleMirjana Malešev; Vlastimir Radonjanin; Snežana Marinković. 2010. "Recycled Concrete as Aggregate for Structural Concrete Production." Sustainability 2, no. 5: 1204-1225.
This paper describes an innovative design of a wireless, passive LC sensor and its application for monitoring of water content in building materials. The sensor was embedded in test material samples so that the internal water content of the samples could be measured with an antenna by tracking the changes in the sensor’s resonant frequency. Since the dielectric constant of water was much higher compared with that of the test samples, the presence of water in the samples increased the capacitance of the LC circuit, thus decreasing the sensor’s resonant frequency. The sensor is made up of a printed circuit board in one metal layer and water content has been determined for clay brick and autoclaved aerated concrete block, both widely used construction materials. Measurements were conducted at room temperature using a HP-4194A Impedance/Gain-Phase Analyzer instrument.
Goran Stojanović; Milan Radovanovic; Mirjana Malešev; Vlastimir Radonjanin. Monitoring of Water Content in Building Materials Using a Wireless Passive Sensor. Sensors 2010, 10, 4270 -4280.
AMA StyleGoran Stojanović, Milan Radovanovic, Mirjana Malešev, Vlastimir Radonjanin. Monitoring of Water Content in Building Materials Using a Wireless Passive Sensor. Sensors. 2010; 10 (5):4270-4280.
Chicago/Turabian StyleGoran Stojanović; Milan Radovanovic; Mirjana Malešev; Vlastimir Radonjanin. 2010. "Monitoring of Water Content in Building Materials Using a Wireless Passive Sensor." Sensors 10, no. 5: 4270-4280.