scholarly journals Characterizing the Performance of Ternary Concrete Mixtures Involving Slag and Metakaolin

2020 ◽  
Vol 5 (2) ◽  
pp. 14
Author(s):  
Matthew S. Sullivan ◽  
Mi G. Chorzepa ◽  
Stephan A. Durham
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Fly Ash ◽  
Coefficient Of Thermal Expansion ◽  
Drying Shrinkage ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Ternary Mixtures ◽  
Modulus Of Rupture ◽  
Ternary Blends

Ternary blends of cementitious materials are investigated. A cement replacement level of 45% is used for all ternary mixtures consisting of 15% metakaolin and 30% slag replacements. Three metakaolin and two blast furnace slag, referred to as ‘slag’ for short, products commercially available are used to compare performance in ternary blends. A mixture with a 45% fly ash replacement is included to serve as a benchmark for performance. The control mixture contains 422 kg of cement per cubic meter of concrete, and a water-to-cementitious material ratio of 0.43 is used for all mixtures with varying dosages of superplasticizer to retain workability. Mixtures are tested for mechanical properties, durability, and volumetric stability. Mechanical properties include compression, split-cylinder tension, modulus of rupture, and dynamic Young’s modulus. Durability measures are comprised of rapid chloride-ion penetrability, sulfate resistance, and alkali–silica reactivity. Finally, the measure of dimensional stability is assessed by conducting drying shrinkage and coefficient of thermal expansion tests. Results indicate that ternary mixtures including metakaolin perform similarly to the control with respect to mechanical strength. It is concluded that ternary blends perform significantly better than both control and fly ash benchmark in tests measuring durability. Furthermore, shrinkage is reduced while the coefficients of thermal expansion are slightly higher than control and the benchmark.

Drying Shrinkage Behavior of Mortars Made with Ternary Blends

2012 ◽  
Vol 2290 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Xuhao Wang ◽  
Fatih Bektas ◽  
Peter Taylor ◽  
Kejin Wang ◽  
Paul J. Tikalsky
Keyword(s):  
Fly Ash ◽  
Response Surface ◽  
Silica Fume ◽  
Surface Analysis ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Response Surface Analysis ◽  
Ternary Blends ◽  
Free Shrinkage ◽  
Shrinkage Behavior

Ternary cementitious blends are widely used in today's concrete mixtures, particularly when high performance is needed. This paper discusses drying shrinkage behavior of mortar mixtures made with various ternary blends. Ternary blends consisting of different combinations of portland or blended cement, slag, fly ash, and silica fume were considered. The amounts of slag, fly ash, and silica fume ranged from 15% to 35%, 13% to 30%, and 3% to 10% by mass of cementitious materials, respectively. Mortar bars were made with the ternary blends and subjected to drying (i.e., temperature = 73° ± 3°F and relative humidity = 50% ± 4%) after standard moist curing for 28 days. Free shrinkage of the bars was assessed at 56 days of age after 28 days of drying. A response surface analysis was done to examine the effects of blend proportions on shrinkage behavior of the mortars. To validate this model, an independent group of mortar mixtures with different ternary combinations was cast, and the measured values were compared with the predicted shrinkage values. The results indicated that of the three supplementary cementitious materials in the ternary blends studied, slag showed a dominant effect on increasing mortar shrinkage. The contribution of Class C fly ash to the shrinkage was slightly less than that of slag. An increase in silica fume or in Class F fly ash content slightly increased free shrinkage. There is a good correlation between the measured shrinkage strain and the strain predicted from the shrinkage model developed from the response surface analysis.

scholarly journals Long-Term Physical and Mechanical Properties and Microstructures of Fly-Ash-Based Geopolymer Composite Incorporating Carbide Slag

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6692
Author(s):  
Xianhui Zhao ◽  
Haoyu Wang ◽  
Linlin Jiang ◽  
Lingchao Meng ◽  
Boyu Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Drying Shrinkage ◽  
Fine Aggregate ◽  
Property Development ◽  
Industrial Solid Waste ◽  
Carbide Slag

The long-term property development of fly ash (FA)-based geopolymer (FA−GEO) incorporating industrial solid waste carbide slag (CS) for up to 360 d is still unclear. The objective of this study was to investigate the fresh, physical, and mechanical properties and microstructures of FA−GEO composites with CS and to evaluate the effects of CS when the composites were cured for 360 d. FA−GEO composites with CS were manufactured using FA (as an aluminosilicate precursor), CS (as a calcium additive), NaOH solution (as an alkali activator), and standard sand (as a fine aggregate). The fresh property and long-term physical properties were measured, including fluidity, bulk density, porosity, and drying shrinkage. The flexural and compressive strengths at 60 d and 360 d were tested. Furthermore, the microstructures and gel products were characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The results show that the additional 20.0% CS reduces the fluidity and increases the conductivity of FA−GEO composites. Bulk densities were decreased, porosities were increased, and drying shrinkages were decreased as the CS content was increased from 0.0% to 20.0% at 360 d. Room temperature is a better curing condition to obtain a higher long-term mechanical strength. The addition of 20.0% CS is more beneficial to the improvement of long-term flexural strength and toughness at room temperature. The gel products in CS−FA−GEO with 20.0% CS are mainly determined as the mixtures of sodium aluminosilicate (N−A−S−H) gel and calcium silicate hydration (C−S−H) gel, besides the surficial pan-alkali. The research results provide an experimental basis for the reuse of CS in various scenarios.

Effect of w/cm and Composition on Correlations of Concrete Electrical Resistivity and Chloride Migration Coefficients

2016 ◽  
Vol 711 ◽  
pp. 21-28
Author(s):  
Francisco J. Presuel-Moreno
Keyword(s):  
Electrical Resistivity ◽  
Steady State ◽  
Fly Ash ◽  
Laboratory Experiments ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Ion Migration ◽  
Resistivity Measurements ◽  
Chloride Migration

The performance with regard to chloride penetration of specimens made with three base compositions (supplementary cementitious materials: 20% fly ash, 20% fly ash + 8% silica fume, and 50% slag replacement by weight of cement), and water-to-cementitious ratios of 0.35, 0.41, or 0.47 were investigated here. In this investigation, laboratory experiments were carried out to study the correlation between electrical resistivity and non-steady state chloride ion migration coefficients (Dnssm) of concrete. NT Build 492 was used to determine chloride migration coefficients. Rapid migration tests and resistivity measurements were performed several times over two years, and the non-steady state migration coefficient (Dnssm) vs. resistivity values were correlated. Experimental results show that a good correlation was found between electrical resistivity and Dnssm. Based on the relationships developed from this investigation, it appears that the correlations are age and composition dependent.

Utilization of Fly Ash in the Synthesis of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 321 ◽  
pp. 131-140
Author(s):  
Martin Nguyen ◽  
Radomír Sokolař
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Power Plants ◽  
Linear Thermal Expansion ◽  
Aluminium Oxide ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Shock Resistance

Forsterite refractory ceramics is utilized in the metallurgical and cement industries as a lining of metallurgical furnaces and rotary kilns for its high refractoriness up to 1850°C and refractoriness under load above 1600°C. Another significant property of forsterite is its coefficient of linear thermal expansion utilized in the electrotechnical industry for ceramic-metal joints. Addition of aluminium oxide into the raw material mixture results in creation of magnesium-alumina spinel (MgO·Al2O3) which improves sintering, thermal shock resistance and mechanical properties in comparison with pure forsterite ceramics. Inexpensive source of aluminium oxide is fly ash. Utilization of fly ash, secondary energetic product of coal-burning power plants, is important for the environment and sustainable development. This paper evaluated properties of fly ash-based forsterite-spinel ceramics in comparison with alumina-based forsterite-spinel ceramics. Forsterite-spinel ceramics was synthesized from olivine, calcined magnesite and fly ash/alumina powders. XRD analysis was used to determine mineralogical composition, thermal analyses were used to determine the behaviour during firing and scanning electron microscopy to determine the morphology of crystal phases. Refractoriness of pyrometric cones, refractoriness under load, thermal shock resistance, coefficient of linear thermal expansion, water absorption, porosity and modulus of rupture were also determined on fired test samples.

The Effect of Homogenization Procedure on Mechanical Properties of High-Performance Concrete with Partial Replacement of Cement by Supplementary Cementitious Materials

2019 ◽  
Vol 292 ◽  
pp. 102-107 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Karel Šeps ◽  
Roman Chylík ◽  
Vladimír Hrbek
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Water Content ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Depth Of Penetration ◽  
Cement Additive

High-performance concrete is a very specific type of concrete. Its production is sensitive to both the quality of compounds used and the order of addition of particular compounds during the homogenization process. The mechanical properties were observed for four dosing procedures of each of the three tested concrete mixtures. The four dosing procedures were identical for the three mixes. The three mixes varied only in the type of supplementary cementitious material used and in water content. The water content difference was caused by variable k-value of particular additives. The water-to-binder ratio was kept constant for all the concretes. The additives used were metakaolin, fly ash and microsilica. The comparison of particular dosing procedures was carried out on the values of basic mechanical properties of concrete. The paper compares compressive strength and depth of penetration of water under pressure. Besides the comparsion of macro-mechanical properties, the effect of microsilica and fly ash additives on micro-mechanical properties was observed with the use of scanning electron microscopy (SEM) and nanoindentation data analysis. Nanoindentation was used to determine the thickness and strength of interfacial transition zone (ITZ) for different sequence of addition of cement, additive and aggregate. The thickness obtained by nanoindentation was further investigated by SEM EDS line scanning.

scholarly journals The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar Containing By-Products

Buildings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 146
Author(s):  
Jakub Hodul ◽  
Nikol Žižková ◽  
Ruben Paul Borg
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chloride Ion ◽  
Capillary Suction ◽  
Chloride Ion Penetration ◽  
Chloride Migration ◽  
Cement Mortars ◽  
Polymer Mortar ◽  
By Products ◽  
Ion Penetration

Crystalline admixtures and industrial by-products can be used in cement-based materials in order to improve their mechanical properties. The research examined long-term curing and the exposure to environmental actions of polymer–cement mortars with crystalline admixture (CA) and different by-products, including Bengħisa fly ash and Globigerina limestone waste filler. The by-products were introduced as a percentage replacement of the cement. A crystallization additive was also added to the mixtures in order to monitor the improvement in durability properties. The mechanical properties of the mortar were assessed, with 20% replacement of cement with fly ash resulting in the highest compressive strength after 540 days. The performance was analyzed with respect to various properties including permeable porosity, capillary suction, rapid chloride ion penetration and chloride migration coefficient. It was noted that the addition of fly ash and crystalline admixture significantly reduced the chloride ion penetration into the structure of the polymer cement mortar, resulting in improved durability. A microstructure investigation was conducted on the samples through Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Crystals forming through the crystalline admixture in the porous structure of the material were clearly observed, contributing to the improved properties of the cement-based polymer mortar.

Determination of Mechanical Properties of Thin Film on Silicon Wafer

2003 ◽  
Author(s):  
Enboa Wu ◽  
Albert J. D. Yang ◽  
Ching-An Shao ◽  
C. S. Yen
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Silicon Wafer ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Bulk State

Nondestructive determination of Young’s modulus, coefficient of thermal expansion, Poisson ratio, and thickness of a thin film has long been a difficult but important issue as the film of micrometer order thick might behave differently from that in the bulk state. In this paper, we have successfully demonstrated the capability of determining all these four parameters at one time. This novel method includes use of the digital phase-shifting reflection moire´ (DPRM) technique to record the slope of wafer warpage under temperature drop condition. In the experiment, 1-um thick aluminum was sputtered on a 6-in silicon wafer. The convolution relationship between the measured data and the mechanical properties was constructed numerically using the conventional 3D finite element code. The genetic algorithm (GA) was adopted as the searching tool for search of the optimal mechanical properties of the film. It was found that the determined data for Young’s modulus (E), Coefficient of Thermal Expansion (CTE), Poisson ratio (ν), and thickness (h) of the 1.00 um thick aluminum film were 104.2Gpa, 38.0 ppm/°C, 0.38, and 0.98 um, respectively, whereas that in the bulk state were measured to be E=71.4 Gpa, CTE=23.0 ppm/°C, and ν=0.34. The significantly larger values on the Young’s modulus and the coefficient of thermal expansion determined by this method might be attributed to the smaller dislocation density due to the thin dimension and formation of the 5-nm layer of Al2O3 formed on top of the 1-um thick sputtered film. The Young’s Modulus and the Poisson ratio of this nano-scale Al2O3 film were then determined. Their values are consistent with the physical intuition of the microstructure.

scholarly journals The Use of Recycled Carpet in Low-Cost Composite Tooling Materials

Recycling ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 12 ◽  
Author(s):  
Kunal Mishra ◽  
Sarat Das ◽  
Ranji Vaidyanathan
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Low Cost ◽  
Value Engineering ◽  
Compressive Properties ◽  
Structural Composites ◽  
Environmental Deterioration ◽  
Composite Tooling

More than 250,000 metric tons (600 million pounds) of carpet are dumped in landfills every year. That creates a significant concern regarding environmental deterioration and economic liability. It is therefore imperative to develop sustainable post-consumer carpet-based products for high-value engineering applications such as composite tooling. To be considered as an acceptable composite tooling material, the composite needs to meet certain required properties such as a low coefficient of thermal expansion, excellent compressive properties, and high a hardness value after repeated exposure to curing cycles. The tooling composites must also exhibit the ability to endure several curing cycles, without deteriorating the mechanical properties. In the present investigation, post-consumer carpet has been recycled in the form of structural composites for tooling applications. The recycled carpet composites have been reinforced with 0.5 wt.% of graphene nanoplatelets to modify the material properties of the carpet composites. The results from compressive and hardness experiments demonstrate that the recycled carpet preserved its mechanical integrity even after several curing cycles. This indicates that recycled carpet composites have the potential to be a low-cost composite tooling alternative for the industry.

Sign in / Sign up

Export Citation Format

Share Document