scholarly journals Influence of Untreated Metal Waste from 3D Printing on Electrical Properties of Alkali-Activated Slag Mortars

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8178
Author(s):  
Lukáš Fiala ◽  
Michaela Petříková ◽  
Martin Keppert ◽  
Martin Böhm ◽  
Jaroslav Pokorný ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
3D Printing ◽  
Metal Powder ◽  
Material Properties ◽  
Nickel Content ◽  
Alkali Activated Slag ◽  
Self Heating ◽  
Activated Slag ◽  
Alkali Activated

The negative environmental impact of cement production emphasizes the need to use alternative binders for construction materials. Alkali-activated slag is a more environmentally friendly candidate which can be utilized in the design of mortars with favorable material properties. However, the electrical properties of such materials are generally poor and need to be optimized by various metallic or carbon-based admixtures to gain new sophisticated material functions, such as self-sensing, self-heating, or energy harvesting. This paper investigates the influence of waste metal powder originating from the 3D printing process on the material properties of alkali-activated slag mortars. The untreated metal powder was characterized by means of XRD and SEM/EDS analyses revealing high nickel content, which was promising in terms of gaining self-heating function due to the high electrical conductivity and stability of nickel in a highly alkaline environment. The designed mortars with the waste metal admixture in the amount up to 250 wt.% to the slag and aggregates were then characterized in terms of basic physical, thermal, and electrical properties. Compared to the reference mortar, the designed mortars were of increased porosity of 17–32%. The thermal conductivity of ~1–1.1 W/m·K was at a favorable level for self-heating. However, the electrical conductivity of ~10−6 S/m was insufficient to allow the generation of the Joule heat. Even though a high amount of 3D printing waste could be used due to the good workability of mixtures, its additional treatment will be necessary to achieve reasonable, effective electrical conductivity of mortars resulting in self-heating function.

Differences in Electrical Properties of Portland Cement and Alkali-Activated Slag Mortars

2018 ◽  
Vol 276 ◽  
pp. 15-20 ◽  
Author(s):  
Pavel Rovnaník ◽  
Maria Míková ◽  
Ivo Kusák ◽  
Patrik Bayer
Keyword(s):  
Electrical Properties ◽  
Portland Cement ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Sodium Ions ◽  
Alkali Activated Slag ◽  
Self Heating ◽  
Chemical Attack ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag is known as a building material for more than sixty years and is considered an alternative to Portland cement based binders. Compared to Portland cement it exhibits some superior properties such as higher resistance against chemical attack and exposure to elevated temperatures. Aluminosilicate binders are generally electrical insulators; however, electrical properties of building materials gain the importance in the new field of applications such as self-sensing or self-heating materials. This paper brings a comparison of the electrical properties, especially resistance and capacitance, between Portland cement and alkali-activated slag mortars. The measurements revealed that alkali-activated slag shows enhanced conducting properties due to the presence of mobile hydrated sodium ions and metallic iron microparticles.

scholarly journals Investigation of Graphene Derivatives on Electrical Properties of Alkali Activated Slag Composites

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4374
Author(s):  
Wu-Jian Long ◽  
Xuanhan Zhang ◽  
Biqin Dong ◽  
Yuan Fang ◽  
Tao-Hua Ye ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrical Properties ◽  
Mechanical Performance ◽  
Structural Defects ◽  
Alkali Activated Slag ◽  
Mechanical And Electrical Properties ◽  
Reduced Graphene ◽  
Graphene Derivatives ◽  
Activated Slag ◽  
Alkali Activated

Reduced graphene oxide (rGO) has been widely used to modify the mechanical performance of alkali activated slag composites (AASC); however, the mechanism is still unclear and the electrical properties of rGO reinforced AASC are unknown. Here, the rheological, mechanical, and electrical properties of the AASC containing rGO nanosheets (0, 0.1, 0.2, and 0.3 wt.%) are investigated. Results showed that rGO nanosheets addition can significantly improve the yield stress, plastic viscosity, thixotropy, and compressive strength of the AASC. The addition of 0.3 wt.% rGO nanosheets increased the stress, viscosity, thixotropy, and strength by 186.77 times, 3.68 times, 15.15 times, and 21.02%, respectively. As for electrical properties, the impedance of the AASC increased when the rGO content was less than 0.2 wt.% but decreased with the increasing dosage. In contrast, the dielectric constant and electrical conductivity of the AASC containing rGO nanosheets decreased and then increased, which can be attributed to the abundant interlayer water and the increasing structural defects as the storage sites for charge carriers, respectively. In addition, the effect of graphene oxide (GO) on the AASC is also studied and the results indicated that the agglomeration of GO nanosheets largely inhibited the application of it in the AASC, even with a small dosage.

Electrical Properties of Alkali-Activated Slag Mortar with Carbon Fibres

2017 ◽  
Vol 908 ◽  
pp. 100-105 ◽  
Author(s):  
Pavel Rovnaník ◽  
Maria Míková ◽  
Ivo Kusák
Keyword(s):  
Mechanical Properties ◽  
Electrical Properties ◽  
Building Materials ◽  
Specific Conductivity ◽  
Carbon Fibres ◽  
Alkali Activated Slag ◽  
Order Of Magnitude ◽  
Activated Slag ◽  
Mixing Water ◽  
Alkali Activated

Building materials with enhanced electrical properties gain the importance in the new field of applications such as self-sensing or self-heating materials. In this paper, 3 mm long carbon fibres were used as a conductive admixture to alkali-activated slag mortar in order to reduce its resistivity. The amount of carbon fibres was ranging from 0.5 to 4.0% of the slag mass and the effect of the conductive admixture on the mechanical properties, electrical impedance, specific conductivity, and microstructure of alkali-activated slag composite was investigated. Only 0.5% of carbon fibres caused a significant decrease in impedance of alkali-activated slag composite and the addition of 4% reduced the impedance by one order of magnitude for low AC frequencies. However, due to problematic dispersion and higher demand of mixing water, the mechanical properties were deteriorated, especially at higher content of carbon fibres.

scholarly journals Electrical and Self-Sensing Properties of Alkali-Activated Slag Composite with Graphite Filler

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1616 ◽  
Author(s):  
Pavel Rovnaník ◽  
Ivo Kusák ◽  
Patrik Bayer ◽  
Pavel Schmid ◽  
Lukáš Fiala
Keyword(s):  
Mechanical Properties ◽  
Electrical Properties ◽  
Compressive Loading ◽  
Conductive Filler ◽  
Graphite Powder ◽  
Alkali Activated Slag ◽  
Sensing Properties ◽  
Activated Slag ◽  
Conductive Properties ◽  
Alkali Activated

The electrical properties of concrete are gaining their importance for the application in building construction. In this study, graphite powder was added to alkali-activated slag mortar as an electrically conductive filler in order to enhance the mortar’s conductive properties. The amount of graphite ranged from 1% to 30% of the slag mass. The effect of the graphite powder on the resistivity, capacitance, mechanical properties, and microstructure of the composite was investigated. Selected mixtures were then used for the testing of self-sensing properties under compressive loading. The results show that the addition of an amount of graphite equal to up to 10% of the slag mass improved the electrical properties of the alkali-activated slag. Higher amounts of filler did not provide any further improvement in electrical properties at lower AC frequencies but caused a strong deterioration in mechanical properties. The best self-sensing properties were achieved for the mixture with 10 wt% of graphite, but only at low compressive stresses of up to 6 MPa.

scholarly journals Flexural and Shear Behaviors of Reinforced Alkali-Activated Slag Concrete Beams

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Kwang-Myong Lee ◽  
Sung Choi ◽  
Jinkyo F. Choo ◽  
Young-Cheol Choi ◽  
Sung-Won Yoo
Keyword(s):  
Material Properties ◽  
Concrete Beams ◽  
Cement Industry ◽  
Reinforced Concrete Beams ◽  
Element Analysis ◽  
Alkali Activated Slag ◽  
Concrete Members ◽  
Activated Slag ◽  
Shear Behaviors ◽  
Alkali Activated

The material properties of cement-zero concrete using alkali-activators have been studied extensively as the latest response to reduce the CO2 exhaust of the cement industry. However, it is also critical to evaluate the behavior of reinforced concrete beams made of alkali-activated slag (AAS) concrete in terms of flexure and shear to promote the applicability of AAS concrete as structural material. Accordingly, nine types of beam specimens with various ratios of tensile steel and stirrup were fabricated and subject to bending and shear tests. The results show that the flexural and shear behaviors of the reinforced AAS concrete members are practically similar to those made of normal concrete and indicate the applicability of the conventional design code given that the lower density of slag is considered. In addition, a framework using the elastic modulus and stress-strain relation from earlier research is adopted to carry out nonlinear finite element analysis reflecting the material properties of AAS concrete. The numerical results exhibit good agreement with the experimental results and demonstrate the validity of the analytical model.

Electrical Properties of Steel Fibre Reinforced Alkali-Activated Slag Composite

2018 ◽  
Vol 760 ◽  
pp. 55-60 ◽  
Author(s):  
Pavel Rovnaník ◽  
Ivo Kusák
Keyword(s):  
Electrical Properties ◽  
Electrical Resistance ◽  
Steel Fibre ◽  
Steel Fibres ◽  
Alkali Activated Slag ◽  
Mechanical And Electrical Properties ◽  
Sensing Material ◽  
Good Conductor ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag is an alternative binder to the ordinary Portland cement. In order to improve its tensile properties steel fibres as dispersed reinforcement can be used. Since steel is very good conductor it changes the electrical properties of alkali-activated slag composite that can have a potential to be used as self-sensing material then. In this study up to 20% of steel fibres by mass of the slag was added to alkali-activated slag mortar and the mechanical properties, electrical resistance, capacitance and microstructure of the composites were investigated. The results showed that the best improvement of both the mechanical and electrical properties can be observed for the composite with 15% of steel fibres.

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