scholarly journals Investigation on Calcined Magnesium-Based Mineral Powder and Its Behavior as Alternative Binder

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
G. Sugila Devi ◽  
K. Sudalaimani
Keyword(s):  
Ph Value ◽  
Sodium Tripolyphosphate ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Heat Of Hydration ◽  
Structural Development ◽  
Initial Setting Time ◽  
Initial Setting

This paper investigates the behavior of calcined powder made of natural magnesite and natural steatite. The magnesite and steatite are made into a powder of ratio 3 : 1 by weight proportion, and the combination is thermally decomposed at a temperature of 1200° Celsius. The calcined powder along with and without Sodium Tripolyphosphate (STPP) salt is tested for its microscopic structural development, consistency, initial setting time, final setting time, and heat of hydration. The powder is made into paste with water/powder ratio as 0.25 and the hardened samples are tested for its compressive strength, drying shrinkage, pH value, SEM analysis, and XRD analysis. The results show that adding phosphate salt increases the hydration process, setting time, and strength aspects. The test samples are found with hydration products such as magnesium hydroxide and struvite. Thus, the present work shows that natural metamorphic magnesite and natural metamorphic steatite can be the potential alternative resource for the production of magnesium-based binder.

scholarly journals Properties of non-standard fly ash – slag cements containing calcareous fly ash

2013 ◽  
Vol 12 (3) ◽  
pp. 215-222
Author(s):  
Katarzyna Synowiec
Keyword(s):  
Fly Ash ◽  
Blast Furnace Slag ◽  
Strength Class ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Initial Setting Time ◽  
Granulated Blast Furnace Slag ◽  
Unfavorable Effect ◽  
Initial Setting ◽  
Furnace Slag

The paper presents the tests results of the properties of non - standard fly ash - slag cements composition. Both natural (unprocessed) and activated by grinding calcareous fly ash was used. It was found that the calcareous fly ash next to the granulated blast furnace slag may be a component of low - clinker cements (ca. 40%). Those cements are characterized by low heat of hydration and overdue of initial setting time in comparison with Ordinary Portland Cement, moreover they have an unfavorable effect on consistency and its upkeep in time. Production of fly ash - slag cements is possible for strength class 32,5 N when the component of cement is raw fly ash, and for strength classes 32,5 N, 32,5 R and 42,5 N when ground fly ash was used. Fly ash activated by grinding was characterized by higher activity.

scholarly journals Influence of Lithium Carbonate on C3A Hydration

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Weiwei Han ◽  
Tao Sun ◽  
Xinping Li ◽  
Zhonghe Shui ◽  
Youzhi Chen ◽  
...  
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Setting Time ◽  
Lithium Ion ◽  
Mineralogical Composition ◽  
Lithium Carbonate ◽  
Initial Setting Time ◽  
Initial Setting ◽  
High Alkalinity ◽  
Cement Setting

Lithium salts, known to ameliorate the effects of alkali-silica reaction, can make significant effects on cement setting. However, the mechanism of effects on cement hydration, especially the hydration of C3A which is critical for initial setting time of cement, is rarely reported. In this study, the development of pH value of pore solution, conductivity, thermodynamics, and mineralogical composition during hydration of C3A with or without Li2CO3 are investigated. The results demonstrate that Li2CO3 promotes C3A hydration through high alkalinity, due to higher activity of lithium ion than that of calcium ion in the solution and carbonation of C3A hydration products resulted from Li2CO3. Li2CO3 favors the C3A hydration in C3A-CaSO4·2H2O-Ca(OH)2-H2O hydration system and affects the mineralogical variation of the ettringite phase(s).

An Investigation on Behavior of Multi-Wall Carbon Nanotubes as an Additive to Cement

2018 ◽  
Vol 24 (8) ◽  
pp. 5832-5835
Author(s):  
A VijayaBhaskar ◽  
M Shanmugasundaram
Keyword(s):  
Carbon Nanotubes ◽  
Setting Time ◽  
Sem Analysis ◽  
Structural Behavior ◽  
Multi Wall Carbon Nanotubes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Cement Binder ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In the present study an attempt was made to study the effect of multi wall carbon nanotubes (MWCNTs) on cement as an additive. The multi-wall carbon nanotubes used in this study has a diameter of 30 nm. This multi walled carbon nanotubes added as additives to cement were in percentage of 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 to weight of cement. Using this modified cement; Binder pastes and mortars were prepared and tested for its various behaviors. The tests were carried for normal consistency, initial setting time, final setting time and strength developments in MWCNTs modified cements. The mortars specimens were further studied for its micro structural behavior through scanning electron microscopy (SEM) analysis. The results show that multi-wall carbon nanotubes increases the strength parameters and micro structural behavior. There were no considerable changes in terms of to the high cost of multi-wall carbon nanotubes, 0.8 percentage can be the optimal percentage of additive in terms of performance and strength.

scholarly journals Optimization of Ternary Binders Based on Flash-Calcined Sediments and Ground Granulated Blast Furnace slag Using a Mixture Design

2021 ◽  
Author(s):  
Ahmed Zeraoui ◽  
Walid Maherzi ◽  
Mahfoud Benzerzour ◽  
Nor-Edine Abriak
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Partial Substitution ◽  
Low Carbon ◽  
Initial Setting Time ◽  
Granulated Blast Furnace Slag ◽  
Initial Setting ◽  
Furnace Slag

CO2 emissions resulting from the production of cement is a major issue, but can be limited by the partial substitution of cement by low-carbon-impact additions. The aim of this study was the formulation of a ternary binder based on ordinary Portland cement (OPC), ground granulated blast-furnace slag (GGBS) and flash-calcined sediment (FCS), a dredged waste which was valorized after applying a new heat treatment: flash calcination. The used materials were physically, chemically and mineralogically characterized. The composition of the formulations was optimized using mixture designs. Five formulations, one reference formulation RM (100% OPC), one binary formulation (50% OPC/50% GGBS), and three ternary formulations with a variable FCS rate (10%, 15%, 20%), were selected and characterized fresh and hardened. Results showed that the incorporation of FCS reduced the workability and increased the density. In addition, a decrease in the initial setting time and the heat of hydration peak were observed. In the hardened state, the formulation containing 10% FCS showed 90-day mechanical strengths superior to that of RM. The use of FCS in ternary binders could reduce the environmental impact by reducing greenhouse gas emissions.

scholarly journals Stabilized mortar with air incorporator agent and plasticizer set retarder: performance measurement

2019 ◽  
Vol 12 (6) ◽  
pp. 1248-1259 ◽  
Author(s):  
A. SCHACKOW ◽  
A. K. FERRARI ◽  
C. EFFTING ◽  
V. O. ALVES ◽  
I. R. GOMES
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Mass Density ◽  
Setting Time ◽  
High Water ◽  
Heat Of Hydration ◽  
Consistency Index ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Air Entraining Agents

Abstract This study aims to develop three stabilized mortars to masonry using air entraining agents and settling retardant plasticizer to compare with a conventional mortar with lime. It was analyzed consistency index, specific gravity, air entrained content, water retentivity, setting time through the heat of hydration, mortar shrinkage/expansion, compressive strength, resistance to sulphate and tensile strength in bonding. The results exhibited that the presence of the settling retardant plasticizer affected the consistency index making the mortar more workable for a longer time. The presence of additives made the stabilized mortars lighter with lower mass density and higher incorporated air content. The presence of lime provided high water retentivity in the conventional mortar while the setting retardant plasticizer improved the water retentivity in the stabilized mortars. The initial setting time of the stabilized mortars occurred after approximately 50 hours. Conventional mortar lost its workability quickly after 2 hours. In conventional mortar, shrinkage occurred, while stabilized mortars had expansion. The conventional mortar exhibited better compressive strength, while the excess of additives can affected negatively this property in the stabilized mortars. Conventional mortar proved to be less resistant to sulphate attack. Tensile strength in bonding was better in a stabilized commercial mortar tested.

Compressive Strength and Setting Time Modification of Class C Fly Ash-Based Geopolymer Partially Replaced with Kaolin and Metakaolin

2018 ◽  
Vol 766 ◽  
pp. 157-163 ◽  
Author(s):  
Khanthima Hemra ◽  
Shuntaro Yamaguchi ◽  
Takaomi Kobayashi ◽  
Pavadee Aungkavattana ◽  
Sirithan Jiemsirilers
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Setting Time ◽  
Xrd Analysis ◽  
Raw Material ◽  
Initial Setting Time ◽  
High Calcium ◽  
Initial Setting ◽  
Class C

Class C fly ash is widely used as a geopolymer raw material. It contains high calcium oxide and iron oxide resulting in a fast setting property. The influence of using kaolin and metakaolin replaced class C fly ash in geopolymer processing were investigated in term of compressive strength and setting time. Kaolin and metakaolin which calcined at different temperature of 600°C and 700°C replaced Class C fly ash between 0 to 50 wt. %. The geopolymers were prepared at constant KOH concentration as 6.0 M, K2SiO3/KOH ratio as 1.0, solid/liquid ratio as 1.5 and 7 days of curing. The compressive strength is obviously increased when fly ash was replaced with both kinds of metakaolin, although, it is inclined to decrease when replaced by kaolin. The compressive strength is increased up to 13% and 47% with the replacement by 50 wt. % of metakaolin calcined at 600°C and 700°C, respectively. On the other hand, the replacement by 50 wt. % of kaolin give the initial setting time prolonging from about 6 min to 80 min. However, the initial setting time of metakaolin calcined at 600°C and 700°C replacement is also improved to about 37 min and 20 min, respectively. These results from their difference of amorphous phase and reactivity of the replacement materials. XRD analysis reveals the combination phases of amorphous geopolymer gel that is the broad hump centered at 28 – 30° 2θ, and products from the reaction such as calcium oxide, arcanite, calcium silicate hydrate, quartz and muscovite which the two latter are from unreacted metakaolin. They are confirmed by FT-IT result and microstructure evaluation by SEM. Therefore, the partially replacement of fly ash with kaolin and metakaolin in fly ash-based geopolymer production are affected to the compressive strength and resulted to modify the setting time.

Modification of Retarder on Desulfurization Gypsum Wall Material

2013 ◽  
Vol 741 ◽  
pp. 45-48 ◽  
Author(s):  
Fu Sheng Niu ◽  
Ai Hong Guo ◽  
Xiang Wen Feng ◽  
Ying Meng
Keyword(s):  
Citric Acid ◽  
Sodium Citrate ◽  
Sodium Tripolyphosphate ◽  
Setting Time ◽  
Sodium Hexametaphosphate ◽  
Wall Material ◽  
Crystal Nucleus ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Initial Setting

In order to broaden the utilization of desulfurization gypsum in China and achieve the direct usage of desulfurization gypsum, in this paper, citric acid (CA), sodium citrate (SCA), sodium tripolyphosphate (STPP), Sodium hexametaphosphate (SP) were selected as retarder to modify desulfurization gypsum. The experiment results are as follows: the effect of SP, STPP, CA, SCA on desulfurization gypsum initial setting time is obvious; the turn is STPP> CA> SCA> SP; when the retarder dosage of STPP in desulfurization gypsum reaches 0.5%, the initial setting time can be extended to 210 min, the final setting time to 240min, which fully meets the demand of gypsum-site construction; inhibiting gypsum particles dissolution and preventing the growth of crystal nucleus are the fundamental reasons of STPP.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Non-Dispersive Anti-Washout Grout Design Based on Geotechnical Experimentation for Application in Subsidence-Prone Underwater Karstic Formations

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1587
Author(s):  
Khaqan Baluch ◽  
Sher Q Baluch ◽  
Hyung-Sik Yang ◽  
Jung-Gyu Kim ◽  
Jong-Gwan Kim ◽  
...  
Keyword(s):  
Fractured Rock ◽  
Setting Time ◽  
Visual Assessment ◽  
Initial Setting Time ◽  
Permeable Sediments ◽  
Coarse Aggregates ◽  
Saturated Rock ◽  
Initial Setting ◽  
Level 3 ◽  
Grey Relational

A new non-dispersive, anti-washout grout consisting of ordinary Portland cement, slag, superplasticizer, and methylbenzyl cellulose is proposed herein for the treatment of open karst, jointed and fractured rock, open-work gravel, and permeable sediments. A series of laboratory experiments were performed to design an anti-wash out grout suitable for grout injection of coarse aggregates depicting partially and open-jointed saturated rock mass and grouting concrete aggregates for underwater construction. The Taguchi orthogonal array was used to obtain nine different grout mix ratios. A total of four variables were considered, each with three different levels of the water–cement ratio, slag, and dosage of additives such as the superplasticizer and methyl benzyl cellulose. The laboratory determination of grout characteristics recording of mini slump, temperature, pH, visual assessment of grout dispersion, bleeding, and initial setting time and as well as uniaxial compressive strengths and permeabilities of the hardened grout samples were tested. To evaluate the suitability of the grout mixes, an analysis of variance was used for factor analysis and Grey relational analysis (GRA) was used to determine the optimal grout mix design. Based on the GRA, the following levels of the factors afforded the best results: water level 1 (0.3%), SP level 3 (0.01%), methylbenzyl cellulose level 2 (0.002%), and slag level 3 (0.1%). This paper describes the research methodology, detailed research observations, and analyses involved in designing the appropriate concrete mix. Based on the conclusions, relevant commendations regarding the suitability of grout testing equipment and grout mix designs are presented.

scholarly journals Sonochemically synthetized ZnO-Graphene nanohybrids and its characterization

2020 ◽  
Vol 59 (1) ◽  
pp. 176-187 ◽  
Author(s):  
Cornel Cobianu ◽  
Niculae Dumbravescu ◽  
Bogdan-Catalin Serban ◽  
Octavian Buiu ◽  
Cosmin Romanitan ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Ph Value ◽  
Raman Band ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Carbon Incorporation ◽  
Additional Amount ◽  
Ph Increase ◽  
Compositional Properties ◽  
Crystalline Symmetry

AbstractThe paper presents the morphological, structural and compositional properties of the sonochemically prepared ZnO-1.4wt% Graphene (Z-G) nanocomposites as a function of pH value of suspension varying from 8.5 to 14 and thermal annealing at 450°C in nitrogen or air ambient. The SEM analysis of the Z-G hybrids dried at 150°C in air has shown a nano-flower like nanostructure for a pH value of 14. The XRD analysis of dried Z-G hybrids revealed a crystallite size increase from 3.5 nm to 18.4 nm with pH increase, and this result was explained in terms of colloids zeta potential evolution with pH value. The Raman and EDS spectroscopy have shown a split of the G band (1575 cm−1) of graphene into two bands (1575 cm−1 and 1605 cm−1), an increased height of D (1323 cm−1) band, and an additional amount of carbon due to CO2 absorption from the air, respectively. The carbon incorporation increased with the decrease of pH, and was associated with a hydrozincite phase, Zn5(CO3)2(OH)6. The formation of dried Z-G nanocomposite was clearly demonstrated only at a pH value equal to 14, where two ZnO Raman active bands at 314.9 cm−1 and 428.2 cm−1 appeared. This result may indicate the sensitivity of the Raman spectroscopy to the nanoflower-like nanostructure of dried Z-G hybrids prepared at pH=14. The thermal treatment of Z-G hybrids in N2at 450°C has increased the number of ZnO Raman bands as a function of pH value, it has decreased the amount of additional carbon by conversion of hydrozincite to ZnO and preserved the graphene profile. The thermal treatment in air at 450°C has increased the crystalline symmetry and stoichiometry of the ZnO as revealed by high and narrow Raman band from 99 cm−1 specific to Zn optical phonons, but it has severely affected the graphene profile in the Z-G hybrid, due to combustion of graphene in oxygen from the ambient.

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