scholarly journals Determination of Selected Physical and Chemical Characteristics of Neem Seed Husk Ash Blended Cement

2019 ◽  
Vol 2 (Issue 1) ◽  
Author(s):  
A.A Raheem ◽  
E.O Ibiwoye
Keyword(s):  
Chemical Composition ◽  
Setting Time ◽  
Blended Cement ◽  
Heat Of Hydration ◽  
Neem Seed ◽  
Initial Setting Time ◽  
Blended Cements ◽  
Final Setting Time ◽  
Total Percentage ◽  
Seed Husk

Neem tree (Azadirachtaindica) is a tropical evergreen tree scattered all over the country, hence its availability can add to the list of materials used as pozzolan. This study investigated the characteristics of Neem Seed Husk Ash (NSHA) blended cement produced in the factory. Neem fruit was collected from Olooru town and Ilorin metropolis in Kwara State Nigeria, after collection, the seed was removed with the use of Decorticator huskers, sun dried for 3 days to reduce its moisture content and burnt in a furnace at a temperature of 650 ± 50 oC. The chemical composition (SiO2, Al2O3 and Fe2O3) and physical characteristics were determined. Blended cement was produced by intergrinding 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by weight of NSHA with Ordinary Portland Cement (OPC) clinker and gypsum. OPC without NSHA served as the control. The blended cements produced were analyzed for chemical composition using X-Ray Flourescence Analyser (XRF). The physico-mechanical properties of blended cement (fineness, initial and final setting time, heat of hydration) produced was examined. The total percentage of SiO2, Al2O3 and Fe2O3 for NSHA is 75.35%. Factory produced NSHA – blended cement is suitable as it satisfied the maximum requirement of 375 minutes for final setting time and 45 minutes minimum initial setting time, hence it can be used for construction work where strength is not a priority

scholarly journals The effects of seawater and nanosilica on the performance of blended cements and composites

2020 ◽  
Vol 10 (12) ◽  
pp. 5009-5026 ◽  
Author(s):  
Pawel Sikora ◽  
Didier Lootens ◽  
Maxime Liard ◽  
Dietmar Stephan
Keyword(s):  
Transport Properties ◽  
Reaction Rate ◽  
Mechanical Performance ◽  
Setting Time ◽  
Blended Cement ◽  
Heat Of Hydration ◽  
Strength Development ◽  
Cement Pastes ◽  
Blended Cements ◽  
Setting Times

AbstractThis study investigates the effects of seawater and nanosilica (3% by weight of cement), on the fresh and hardened properties of cement pastes and mortars produced with two types of low heat cements: Portland pozzolana cement (CEM II) and blast furnace cement (CEM III). The heat of hydration, initial and final setting times, rheological properties, strength development, sorptivity and water accessible porosity of the cement pastes and mortars were determined. The data reveal that cement type has a significant effect on the reaction rate of cement with seawater and nanosilica (NS). Specimens produced with slag-blended cement exhibited a higher cement reaction rate and the composite produced exhibited better mechanical performance, as a result of the additional reaction of alumina rich phases in slag, with seawater. Replacement of freshwater with seawater contributes mostly to a significant improvement of early strength. However, in the case of slag-blended cement, 28 day strength also improved. The incorporation of NS results in additional acceleration of hydration processes, as well as to a decrease in cement setting time. In contrast, the addition of NS results in a noticeable increment in the yield-stress of pastes, with this effect being pronounced when NS is mixed along with seawater. Moreover, the use of seawater and NS has a beneficial effect on microstructure refinement, thus improving the transport properties of cement mortars. Overall, the study has showed that both seawater and NS can be successfully used to accelerate the hydration process of low heat blended cements and to improve the mechanical and transport properties of cement-based composites.

scholarly journals Effect of Chemical Composition and Network of Fly Ash Glass on the Hydration Process and Properties of Portland-Fly Ash Cement

2021 ◽  
Author(s):  
Ewelina Tkaczewska
Keyword(s):  
Fly Ash ◽  
Chemical Composition ◽  
Strength Class ◽  
Saturation Index ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Point Of View ◽  
Hydration Process ◽  
Initial Setting Time ◽  
Aluminum Ions

AbstractIn the experiment, the aluminosilicate glasses with aluminum saturation index (ASI), defined as the Al2O3/(Na2O+K2O+2CaO), equal to 0.74, 1.72. 2.52, or 4.05 were synthesized. The spectroscopy tests (MIR and 27Al MAS-NMR) confirm that in glass with ASI < 1, the aluminum ions occur in the [AlO4]5- only. In glasses with ASI > 1, the aluminum ions create mainly [AlO4]5-, but part of them occurs in the form of [AlO6]9-. The content of [AlO6]9- octahedrons increases successively for ASI from 1.72 to 4.05. Glass with ASI equal to 4.05 demonstrates the highest content of pozzolanic active Al2O3. Model ashes were prepared by mixing 70 wt.% of glass, 20 wt.% of synthetic mullite and 10 wt.% of SiO2 as an equivalent of quartz. Then Portland cement CEM I 42.5R was milled together with 20 wt.% of each of model ashes to Blaine’s specific surface area of 4,200±50 cm2 g-1. It was found that the addition of ash with higher content of [AlO6]9- octahedrons in the structure of glass accelerates the hydration process of cement blend, which, in turn, positively affects its usable features (heat of hydration, initial setting time and compressive strength). According to the requirements of PN-EN 197-1:2012 standard, the introduction of ash with ASI coefficient equal to 4.05 gives cement blend of strength class of 52.5N. Cement blends with the ash of ASI value equal to 1.72 and 2.52 correspond to strength class of 32.5R, whereas the cement blend with the ash of ASI value equal to 0.74 does not achieve the minimum value of strength for any cement strength class. Results show that the change in chemical composition of fly ash glass and resulting from this diversified structure are essential from the point of view of hydration and properties of cement containing fly ashes in its composition.

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 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.

Design Procedure Concerning Composition of Composites Containing Gypsum-Free Cement

2012 ◽  
Vol 450-451 ◽  
pp. 719-726
Author(s):  
Jiří Brožovský ◽  
Jiri Zach
Keyword(s):  
Chemical Composition ◽  
Setting Time ◽  
Design Procedure ◽  
Concrete Surface ◽  
Cement Concrete ◽  
Concrete Composition ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Similar Character ◽  
Principal Property

Composites containing gypsum-free cement features quick strength rise at the age between 1 and 3 days. Such property predestine gypsum-free cement concrete for repair of building constructions that are to be put into service as soon as possible. Repair of concrete-cement pavements and surfaces of similar character belongs to one of field of gypsum-free cement concrete application. Materials of these constructions shall comply not only with required strength characteristics but also with needed durability. That is why resistance to alternate frost, thawing and chemical deicing substances is the principal property of GFC concrete surface. Properties of gypsum-free cement concrete – whether fresh or hardened – are mainly affected by following factors: properties of gypsum-free cement (fineness of grinding, quantity of admixtures controlling initial setting time, clinker chemical composition) as well as mineralogical and chemical composition of natural compact aggregates, and water-cement ratio. Factors listed above are to be taken into account also during design of gypsum-free cement concrete composition. This article deals with design procedure concerning composition of concrete containing gypsum-free cement considering its specificities.

Effect of Citric Acid on Cement Hydration

2011 ◽  
Vol 393-395 ◽  
pp. 49-53 ◽  
Author(s):  
Bao Guo Ma ◽  
Jun Xiao ◽  
Hong Bo Tan
Keyword(s):  
Citric Acid ◽  
Cement Hydration ◽  
Setting Time ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Retarding Effect ◽  
Initial Setting ◽  
Flow Loss ◽  
Diffraction Peaks ◽  
Acid Dosage

Through the test of citric acid of cement paste, setting time and compression strength changes, and combined with XRD, SEM, discusses the influence of citric acid on cement hydration process. The results show that: citric acid can effectively increase the initial cement fluidity, when the content is exceed to 0.1%, the 60 min flow loss of increased gradually. Citric acid retarding effect increases with dosage, but there is a critical dosage, when the dosage is less than 0.1%, the initial setting time and final setting time increased slowly; When the dosage more than 0.1%, the initial setting time increased slowly, but the final setting time increases rapidly; With the increase in citric acid dosage, AFt diffraction peaks increases, while the CH peak decreases, indicating that the citric acid accelerated the initial hydration of C3A, while inhibiting C3S hydration and promoting AFt generation

SETTING TIME AND HEAT OF HYDRATION OF WASTEPAPER SLUDGE ASH-GROUND GRANULATED BLASTFURNACE SLAG BLENDED CEMENTS

2005 ◽  
pp. 825-834 ◽  
Author(s):  
Arnon Chaipanich ◽  
J Bai ◽  
M O'Farrell ◽  
J M Kinuthia ◽  
B B Sabir ◽  
...  
Keyword(s):  
Setting Time ◽  
Heat Of Hydration ◽  
Blended Cements ◽  
Blastfurnace Slag ◽  
Sludge Ash

Experimental Research on Coal Gangue Grouting Material for Gob Filling

2013 ◽  
Vol 357-360 ◽  
pp. 1158-1166
Author(s):  
Tian Feng Gu ◽  
Zhong Di Sun ◽  
Feng Tao Luo ◽  
Kang Guo ◽  
Ya Ming Liu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Compression Strength ◽  
Raw Materials ◽  
Setting Time ◽  
Blended Cement ◽  
Coal Gangue ◽  
Activation Process ◽  
Initial Setting Time ◽  
Wide Range ◽  
Coal Gob

Grouting fill is one of the main methods of coal gob treatment. The grouting properties directly affect the effect of grouting treatment. Cement-fly ash grout is widely used in the treatment of coal gob. But in many gob grouting fill projects, due to the lack of fly ash, we need to look for other low-cost grouting materials. Study was made through laboratory experiment on the properties of cement-coal gangue materials used for the gob grouting. In this paper, the correlation of water-solid ratio, cement content, admixture, concretion compression strength, setting time, viscosity, water segregation rate and hardening rate is discussed in the case of use of large gangue content cement. The test results show that compared with the grout not go through the activation process, the blended cement grout mixed with coal gangue powder activated by low temperature and mechanical crushing has high concretion compression strength. Water glass has a great effect on the viscosity, initial setting time and final setting time, which can be used to adjust the grout properties to accommodate grouting environment requirements. This grout has the advantage of wide range sources of raw materials, and can be used to solve the lack of fly ash and gangue resource utilization problems.

Performances Study and Accelerating Mechanism Analysis of New-Type Alkali-Free Efficient Liquid Setting Accelerator

2014 ◽  
Vol 584-586 ◽  
pp. 1652-1658 ◽  
Author(s):  
Tong Wei Lu ◽  
Fei Xiao ◽  
Lei Guo ◽  
Gui Bo Gao
Keyword(s):  
High Performance ◽  
Setting Time ◽  
Aluminum Silicate ◽  
Mechanism Analysis ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Calcium Aluminates ◽  
Magnesium Aluminum Silicate ◽  
Initial Setting ◽  
New Type

This paper introduces a new-type alkali-free and chlorine-free high performance liquid accelerated admixture. The accelerated agent is mainly composed of the following components: fluoride magnesium aluminum silicate is main accelerator, alcohol amine polymer is activator, and amide polymer is stabilizer. When dosage of the admixture is greater than 4%, the cement initial setting time is less than 5 min, the final setting time is less than 10 min, and the 28 day compressive strength ratio of mortar is more than 100%. The mechanism is the accelerating of agent on hydration of C3A and C3S. There are large hydration calcium flu silicate (11CaO·4SiO2·CaF2) and hydration calcium aluminates at the later stage of hydration.

scholarly journals Compressive Strength and Setting Time of MTA and Portland Cement Associated with Different Radiopacifying Agents

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Mario Tanomaru-Filho ◽  
Vanessa Morales ◽  
Guilherme F. da Silva ◽  
Roberta Bosso ◽  
José M. S. N. Reis ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Zirconium Oxide ◽  
Setting Time ◽  
Strontium Carbonate ◽  
Strength Test ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Compressive Strength Test ◽  
Initial Setting

Objective. The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5 mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and the Tukey tests, at 5% significance. Results. After 24 hours, the highest values were found for PC and PC + ZO. At 21 days, PC + BO showed the lowest compressive strength among all the groups. The initial setting time was greater for PC. The final setting time was greater for PC and PC + CT, and MTA had the lowest among the evaluated materials (P<0.05). Conclusion. The results showed that all radiopacifying agents tested may potentially be used in association with PC to replace BO.

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