scholarly journals Effect of Calcareous Fly-ash Processing Methods on Rheological Properties of Mortars

2018 ◽  
Author(s):  
Jacek Gołaszewski ◽  
Zbigniew Giergiczny ◽  
Tomasz Ponikiewski ◽  
Aleksandra Kostrzanowska-Siedlarz ◽  
Patrycja Miera
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Negative Influence ◽  
Plastic Viscosity ◽  
Processing Methods ◽  
Yield Value ◽  
Selective Collection

The paper presents the results of research into the influence of calcareous fly ash (CFA) processing methods on the rheological properties of mortars. The study consisted of a comparison of changes of the rheological properties (plastic viscosity and yield value) of the mortars during 90 minutes when CFA, unprocessed or processed by grinding, grain separation, or selective collection from the filter, was used as a substitute for a part of the cement. The results show that processing of CFA decreases its negative influence on the rheological properties; the efficient methods are separation or grinding, while the effect of selective collection is almost insignificant.

scholarly journals Influence of Nano-SiO2, Nano-CaCO3 and Nano-Al2O3 on Rheological Properties of Cement–Fly Ash Paste

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2598 ◽  
Author(s):  
Yiming Peng ◽  
Kunlin Ma ◽  
Guangcheng Long ◽  
Youjun Xie
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Yield Stress ◽  
Free Water ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Plastic Viscosity ◽  
Behavior Changes ◽  
Nano Sio2 ◽  
Resting Time

Rheological curves of cement–fly ash (C–FA) paste incorporating nanomaterials including nano-SiO2 (NS), nano-CaCO3 (NC) and nano-Al2O3 (NA) at different resting times (hydration time of 5 min, 60 min, and 120 min) were tested with a rheometer. The rheological behaviors were described by the Herschel–Bulkley (H–B) model, and the influences of these nanomaterials on rheological properties of C–FA paste were compared. Results show that the types, content of nanomaterials and resting time have great influences on the rheological properties of C–FA paste. Incorporating NS and NA increases yield stress and plastic viscosity, and decreases the rheological index of C–FA paste. When the content of NS and NA were 2 wt%, the rheological index of C–FA paste was less than 1, indicating rheological behavior changes from shear thickening to shear thinning. Meanwhile, with rising resting time, yield stress and plastic viscosity increased significantly, but the rheological index decreased evidently, showing paste takes on shear thinning due to the rise of resting time. However, incorporating 3 wt% NC and the rising of resting time did not change the rheological properties of C–FA paste. These differences are mainly that the specific surface area (SSA) of NS (150 m2/g) and NA (120 m2/g) are much larger than that of NC (40 m2/g). The huge SSA of NS and NA consume lots of free water and these tiny particles accelerate the hydration process during resting time.

scholarly journals Influence of Waste Fly Ash on the Rheological Properties of Fresh Cement Paste and the Following Electrical Performances and Mechanical Strengths of Hardened Specimens

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1558
Author(s):  
Lili Cui ◽  
Hui Wang
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Cement Paste ◽  
Electrical Resistance ◽  
Plastic Viscosity ◽  
Hardened Cement ◽  
Testing Time ◽  
Curing Time ◽  
Slump Flow ◽  
Mechanical Strengths

Waste fly ash (WFA) is a kind of solid waste without reasonable disposition. The WFA with active substance can promote the cement hydration, therefore, WFA may enhance the mechanical strengths of cement-based materials. In this paper, the rheological properties (slump flow and plastic viscosity) of fresh cement paste with WFA ranging from 0% to 25% by mass ratio of cement were studied. The alternating current (AC) electrical resistance and direct current (DC) resistance time curves were determined. The AC impedance spectroscopy curves of the specimens cured for 1 day and 28 days were obtained. Finally, the mechanical strengths of hardened cement paste cured for 1 day, 3 days, 7 days, and 28 days were tested. The results showed that the slump flow was decreased and the plastic viscosity was increased by the addition of WFA and the increasing curing time. The AC electrical resistance increased in the form of the quadratic function with the cuing age. Meanwhile, the addition of WFA demonstrated an enhancing effect on the electrical conduction of cement paste. The variation rate of DC electrical resistance during the testing time increased with the increasing dosages of WFA and the curing age. The mechanical strengths increased with the addition of curing time and the content of WFA. The increasing rate of mechanical strengths increased with the addition of WFA (0~15%) and decreased with curing time. However, when the dosage of WFA increased from 15% to 25%, the increasing rate decreased.

scholarly journals The Influence of Calcareous Fly Ash on the Effectiveness of Plasticizers and Superplasticizers

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2245
Author(s):  
Jacek Gołaszewski ◽  
Tomasz Ponikiewski ◽  
Aleksandra Kostrzanowska-Siedlarz ◽  
Patrycja Miera
Keyword(s):  
Sustainable Development ◽  
Fly Ash ◽  
Rheological Properties ◽  
Water Demand ◽  
High Water ◽  
Heat Of Hydration ◽  
Yield Value ◽  
High Calcium ◽  
Concrete Mix ◽  
Polycarboxylate Ether

Due to the rational shaping of the environment and the management of environmental resources in accordance with the principle of sustainable development, calcareous fly ash (CFA)—high-calcium as a by-product of lignite combustion—is a valuable addition to concrete. This additive, however, due to its high-water demand lowers the workability of the concrete mix, which is a problem, especially in the first 90 min after mixing the components of the mix. In order to meet this challenge, plasticizers (P) and superplasticizers (SP) for concrete are used with various effects which are designed to reduce the yield value and plastic viscosity. To check the technical efficiency of admixtures P and SP with different chemical bases, the main objective of this research was to investigate the influence of raw and ground CFA on the rheological properties and other side effects of admixtures, such as the amount of air in the mixture and the amount of heat of hydration. The use of P, particularly SP, effectively improves the workability of the mortar containing CFA, especially ground CFA. With these admixtures, it is possible to obtain mortars containing ground CFA with similar rheological properties to mortars without its addition. To obtain a specific workability of mortar with CFA, it is usually necessary to introduce a higher dose of P or SP than used for mortars without CFA. The presence of raw CFA does not alter the effectiveness of P and strongly reduces the effectiveness of SP. The reduced effectiveness of SP manifests primarily as a high workability lost. The presence of ground CFA does not change the effectiveness of P (or is higher). The effectiveness of the superplasticizer SNF (with a chemical base of naphthalene sulfonate) and PE (with a chemical base of polycarboxylate ether) is slightly lower or does not change. The effectiveness of the superplasticizer SMF (with a chemical base of melamine sulfonates) is significantly lower. We found that the presence of ash affects the efficiency of P and SP, while processing via the grinding of ash makes the effect negligible. These results are novel in both their cognitive and practical aspects.

INFLUENCE OF VISCOSITY ENHANCING AGENT ON RHEOLOGY AND COMPRESSIVE STRENGTH OF SUPERPLASTICIZED MORTARS

2009 ◽  
Vol 15 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Jacek Gołaszewski
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Plastic Viscosity ◽  
Basic Relation ◽  
Rheological Parameters ◽  
Bingham Model ◽  
Yield Value

The results of investigation into the influence of Viscosity Enhancing Agents (VEA) on the rheological properties of mortars, different in cement and superplasticizer properties, are presented and discussed. Rheology results have been evaluated according to the Bingham model, which describes the rheology with 2 parameters: yield value and plastic viscosity. Rheological parameters were measured using Two‐Point Workability Test (TPWT). Additionally, the influence of VEA on compressive strength of mortars is presented. It was found that effects of VEA addition on rheological properties of mortars, as well as on compressive strength of mortars, significantly depend on cement and superplasticizer properties. Basic relation of influence of VEA on rheological properties and compressive strength of mortars in respect to cement and superplasticizer properties were presented and discussed. It is concluded that addition of VEA influences compatibility between cement and superplasticizer. Because addition of VEA may cause decrease in compressive strength, the assessment of compatibility of VEA ‐ cement ‐ superplasticizer system should be performed in relation not only to rheological properties, but also to compressive strength. Santrauka Straipsnyje pateikta ir išanalizuota klampą didinančių priedų įtaka skiedinių reologinėms savybėms. Skiediniai buvo ruošiami su įvairių savybių cementais ir superplastikliais. Reologijos tyrimų rezultatai įvertinti remiantis Binghamo modeliu. Reologinės savybės buvo tiriamos dviejų parametrų reometru (TPWT). Taip sudarytas naturalus šviežio skiedinio ir betono mišinio reologinės elgsenos būvis. Straipsnyje taip pat pateikti klampą didinančių priedų įtakos betono stipriui giuždant rezultatai. Nustatyta, kad klampą didinančių priedų poveikio efektas skiedinių reologinėms savybėms ir stipriui gniuždant iš esmės priklauso nuo cemento ir superplastiklių savybių.

Influence of Monomer on the Transfer Properties of UV Waterless Offset Ink

2012 ◽  
Vol 200 ◽  
pp. 719-723
Author(s):  
Bei Qing Huang ◽  
Xiao Xue Jia ◽  
Xian Fu Wei ◽  
Ling Ya Gu ◽  
Biao Fan
Keyword(s):  
Rheological Properties ◽  
Transfer Equation ◽  
Transfer Rate ◽  
Large Impact ◽  
Transfer Performance ◽  
Transfer Experiment ◽  
Printing Quality ◽  
Yield Value ◽  
Ink Transfer ◽  
Transfer Properties

Four kinds of monomers were chosen to prepare ink to research the effect of monomer on the ink transfer performance of UV waterless offset and improve the printing quality. The rheological properties such as viscosity, yield value, thixotropy and stickiness were tested and the ink transfer equation was built, the ink transfer rate was calculated and the effect of monomer on the ink transfer performance was analyzed through the ink transfer experiment. The research results show that the type of monomers has large impact on the rheological properties of UV waterless offset, so the ink transfer performances with different kinds of monomers are different. And the viscosity, thixotropy, yield value and stickiness of the ink with TPGDA and EOEOEA are little, the ink transfer performance is better.

Rheological Properties of Cement Paste Blended Blast Furnace Slag or Fly Ash Powder

2008 ◽  
Vol 45 (6) ◽  
pp. 336-344 ◽  
Author(s):  
Jong-Taek Song ◽  
Hyo-Sang Park ◽  
Seung-Ho Byun ◽  
Dong-Woo Yoo
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Rheological Properties ◽  
Cement Paste ◽  
Blast Furnace Slag ◽  
Furnace Slag

Thermal and rheological properties of polyamide 6/layered double hydroxide clay composites

2019 ◽  
Vol 27 (9) ◽  
pp. 567-581 ◽  
Author(s):  
RDS Zwane ◽  
ER Sadiku ◽  
SS Ray ◽  
NE Luruli
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Rheological Properties ◽  
Layered Double Hydroxide ◽  
Polyamide 6 ◽  
Negative Influence ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Double Hydroxide ◽  
Nucleating Effect

Thermal and rheological properties of polyamide 6/layered double hydroxide (PA6/LDH) composites were studied. Pristine (U-LDH) and organically modified (M-LDH) clays were used in this study. Some evidence of intercalation was observed on the microstructure of PA6/M-LDH samples, while PA6/U-LDH was characterised by microcomposite morphology as shown by the transmission electron microscopy results. The scanning electron microscopy results showed a complete delamination of the M-LDH in the PA6 matrix while U-LDH was evenly dispersed as immiscible tactoids. In the melt state, the M-LDH had a significant influence on the melt microstructure of PA6 matrix when compared to U-LDH. Differential scanning calorimetry results, both dynamic and isothermal experiments, showed that LDH had a heterogeneous nucleating effect on the PA6 matrix, with the U-LDH showing better nucleating effect when compared to M-LDH. The thermogravimetric analysis results showed that M-LDH had a negative influence on the thermal stability of the composites, while U-LDH improved their thermal stability. The X-ray diffraction and dynamic mechanical analysis results showed that the presence of M-LDH promoted the formation of γ-crystallites in the PA6 matrix, while U-LDH composites were dominated by the α-crystallites. This phenomenon had a positive correlation with increasing content of both LDH clays. An overall improved dynamic mechanical properties were observed for PA6/U-LDH when compared to PA6/M-LDH composites.

scholarly journals Effects of Fly Ash and Chemical Admixtures on the Rheological Properties of High-Concentration Full-Tailing Filling Slurry

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Fulin Wang ◽  
Faguang Yang ◽  
Zhengping Yuan ◽  
Shijiao Yang
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Yield Stress ◽  
Polyethylene Oxide ◽  
Viscosity Coefficient ◽  
Pipeline Transportation ◽  
High Concentration ◽  
Polycarboxylate Superplasticizer ◽  
Chemical Admixtures

Good fluidity is the precondition to ensure the pipeline transportation of the filling slurry. The admixture in the filling slurry will affect the rheological properties of the slurry. In this paper, yield stress (YS), viscosity coefficient (VC), and expansion (ED) of the filling slurry were measured by the MCR52 rheometer and expansion tester, respectively, and the influence regularities of the three kinds of admixtures including fly ash (FA), polycarboxylate superplasticizer (PS), and polyethylene oxide (PEO) on the rheological properties of the filling slurry were obtained. The results show that when other conditions are fixed, the fluidity of the slurry becomes worse with the increase of the amount of fly ash but improves with the increase of the amount of the polycarboxylate superplasticizer; polyethylene oxide is not suitable for the improvement of the fluidity of the high-concentration full-tailing filling slurry, and the fluidity of the slurry becomes worse rapidly with the increase of the amount of polyethylene oxide.

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