Application of a-SiO2 Rich Additives in Cement Paste

2015 ◽  
Vol 749 ◽  
pp. 362-367 ◽  
Author(s):  
Jaroslav Pokorný ◽  
Milena Pavlíková ◽  
Eva Navrátilová ◽  
Pavla Rovnaníková ◽  
Zbyšek Pavlík ◽  
...  
Keyword(s):  
Cement Paste ◽  
Bending Strength ◽  
Setting Time ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Fast Reaction ◽  
Cement Pastes ◽  
Matrix Density ◽  
Physical And Chemical ◽  
And Chemical Properties

The effect of a-SiO2 of various origin on the properties of cement paste with incorporated different silica containing materials is experimentally studied in the paper. For the applied a-SiO2 materials, basic physical and chemical properties are accessed, together with their chemical composition. Amount of amorphous phase of SiO2 in particular siliceous materials is determined using XRD analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated a-SiO2 containing materials, together with initial and final setting time of fresh mixtures. The obtained data give evidence on a high and fast reaction activity of tested siliceous materials which results in a significant improvement of porosity and mechanical strength of a-SiO2 modified cement pastes.

scholarly journals The influence of sulfate availability on rheology of fresh cement paste

2020 ◽  
Vol 30 (1) ◽  
pp. 54-63
Author(s):  
Willy Mbasha ◽  
Rainer Haldenwang ◽  
Irina Masalova
Keyword(s):  
Yield Stress ◽  
Calcium Sulfate ◽  
Chemical Properties ◽  
Plastic Viscosity ◽  
Cement Clinker ◽  
Flow Properties ◽  
Cement Pastes ◽  
Hardened Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractNatural gypsum can degenerate into hemihydrate during cement clinker grinding which changes the physical and chemical properties of cement hydration, affecting therefore the fresh and hardened properties of cement based materials. Cement systems containing a constant total amount of calcium sulfate (4%) with relative proportions of hemihydrate and natural gypsum were considered. Rheological measurements were executed on an Anton Paar MCR51 rheometer to evaluate the flow properties of cement pastes. Results show that, the yield stress and the plastic viscosity of cement pastes were affected when the degeneration of natural gypsum exceeded 50%. Above this concentration, the yield stress remarkably increased and a variation in plastic viscosity of about 50% was observed. Using TG-DSC techniques, it was shown that, the amount of formed ettringite could not explain these rheological changes. However, centrifugational packing and SEM-SE measurements confirmed that, more than the amount of ettringite precipitated, ettringite morphology plays a major role in controlling the yield stress and plastic viscosity of fresh cement pastes.

Preparation and Performance of Andalusite Bonded SiC Solar Heat-Absorbing Ceramics

2013 ◽  
Vol 320 ◽  
pp. 52-59
Author(s):  
Jian Feng Wu ◽  
Meng Liu ◽  
Xiao Hong Xu ◽  
Ya Xiang Zhang ◽  
Kun Li ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Bending Strength ◽  
Thermal Power ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Expansion Rate ◽  
Testing Technology ◽  
Firing Shrinkage ◽  
And Performance ◽  
Physical And Chemical

Using andalusite, SiC, Su Zhou Kaolin and Guang Xi quartz as materials, andalusite bonded SiC heat absorbing ceramic was prepared by pressureless firing in the ceramic preparation process. The influence of gradient SiC on microstructure and properties of the samples were studied. Using the testing technology of XRD, SEM, and etc., physical and chemical properties, phase composition and microstructure were tested and analysised.The results indicate that andalusite bonded SiC heat absorbing ceramic, which prepared to have a low firing shrinkage rate, high refractoriness and a good microstructure. The best firing temperature of the best formula C4 is 1460°C, firing expansion rate is 0.98%, bending strength is 32.52MPa,porosity is 30.74%, bulk density is 2.05g·cm-3, refractoriness is 1650°C,growth rate of oxidation weight is 2.769mg·cm-2and have no crack after 30 times thermal shock. The bending strength has increased 11.15% after thermal shock. XRD analysis indicated that the main phase compositions are α-SiC, mullite and cristobalite.SEM studies show that there are many connected pores in the samples, the diameters of the pores are 10~20μm. Andalusite bonded SiC heat absorbing ceramic have a low firing expansion rate, high bending strength and good microstructure, which is suit for tower type solar thermal power generation.

scholarly journals Factors Affecting the Setting Time of Fly Ash-Based Geopolymer

2016 ◽  
Vol 841 ◽  
pp. 90-97 ◽  
Author(s):  
Antoni ◽  
Stephen Wibiatma Wijaya ◽  
Djwantoro Hardjito
Keyword(s):  
Fly Ash ◽  
Initial Temperature ◽  
Ph Value ◽  
Setting Time ◽  
Chemical Properties ◽  
Curing Temperature ◽  
Factors Affecting ◽  
Ph Values ◽  
Physical And Chemical ◽  
And Chemical Properties

Fly ash is a waste from coal burning, that are generated with fluctuation both in its physical and chemical characteristics. This characteristics of fly ash when used in the making of geopolymer concrete will greatly affect the final products obtained. The pH value measured in fly ash, according previous research, can influence the setting time of geopolymer and fly ash with high pH values can cause flash-setting in the concrete. Understanding more clearly about the factors that affect the setting time of fly ash based geopolymer is important for further progress and development of the material. It was found that factors that influence the setting time of geopolymer was not only from the physical and chemical properties of the fly ash itself. Other factors such as composition and mix design, manufacturing process and environmental conditions can also affect its setting time. The experimental results showed that fly ash particle size, CaO and MgO content, in addition to ratio of sodium silicate and sodium hydroxide in the alkali solution, molarity of NaOH, initial temperature of the mixture, curing temperature, and mix volume could potentially influence the setting time of the geopolymer mixture.

scholarly journals Effectiveness of Reinforcing Bent Non-Uniform Pre-Stressed Glulam Beams with Basalt Fibre Reinforced Polymers Rods

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3141 ◽  
Author(s):  
Agnieszka Wdowiak ◽  
Janusz Brol
Keyword(s):  
Bearing Capacity ◽  
Bending Strength ◽  
Positive Impact ◽  
Wood Quality ◽  
Chemical Properties ◽  
Basalt Fibre ◽  
Reinforced Polymers ◽  
Physical And Chemical ◽  
The Impact ◽  
And Chemical Properties

The article presents the testing designating the impact of structural non-uniformity on the effectiveness of reinforcing bent wooden beams reinforced with basalt fibre (BFRP—Basalt Fibre Reinforced Polymers) rods. The obtained results demonstrate a positive impact of the strengthening in improving the bearing capacity and rigidness of the wooden beams. The article presents the impact of selected physical and chemical properties of wooden elements on the achieved strengthening reliability, increase in bearing capacity and the estimation of the reduction of deflections and stresses of bent beams, made from various wood quality classes and reinforced using BFRP rods. The conducted testing featured an analysis of the ability of using lower quality class lumber to strengthen the beams with pre-stressed basalt fibre rods. This solution allows for reducing the cross-section or lower the class of used wood with simultaneous maintenance of comparable rigidity and bending strength of beams, as in the non-strengthened beams.

scholarly journals Evaluation of Weld Joint: Cupro – Nickel with Aluminium 5083

2019 ◽  
Vol 8 (3) ◽  
pp. 5457-5463
Keyword(s):  
Weld Joint ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Metal Plates ◽  
Dissimilar Alloys ◽  
Ni Alloy ◽  
Sem Imaging ◽  
Physical And Chemical ◽  
The Impact ◽  
And Chemical Properties

Cupro-Nickel and Aluminium alloy to their series, Al 5083 and 70Cu30Ni are the critical alloys in ship building mainly in piping section. Due to the reason of having a huge difference in their physical and chemical properties, obtaining a good bonding between them by welding is rather a tough job. The welding was conducted by giving waviness to the torch and allowing the molten pool of Cu-Ni to flow towards the Al 5083 and thereby joining them without melting the aluminium. The microstructure was studied by welding plain plates as well as Nickel coated plates. The microstructural study showed that there is a good bonding between the two alloys. The SEM imaging confirms the bonding of the two alloys at the welded region. The elemental composition of the weld joint was found by EDS analysis. The formation of intermetallics was confirmed by XRD analysis. Then the hardness at the weld joint was studied. The hardness value obtained from testing was promising and there with showing a good properties at the welded joint. The Ni coated welded alloys showed significant and improved results when comparing with the non-nickel plated metal plates. With the hardness value varying from the non Ni coated plates was found to be high compared to the hardness value of the Al and Cu-Ni alloy. But the further study showed that that hardness value adds much to the weld stability by the formation of good bonds between the alloys and that of the intermetallics formed. The impact tests conducted on the welded specimen shows good results with regards to the comparison with the impact strength of 70Cu30Ni and the energy absorbed by the welded specimen. The results showed that welding is possible between these alloys and the nickel coated alloys shows better results in strength and bonding than non- nickel coated alloys. This study also confirms that GTAW can be very effective in joining these dissimilar alloys.

Preparation of Porous Ceramics Using Different Pore-Forming Agents

2013 ◽  
Vol 647 ◽  
pp. 711-714 ◽  
Author(s):  
Fang Zhang ◽  
Chao Kai Wen
Keyword(s):  
Bending Strength ◽  
Chemical Properties ◽  
Porous Ceramics ◽  
Physical And Chemical Properties ◽  
Crystalline Phases ◽  
Study Results ◽  
Two Samples ◽  
Physical And Chemical ◽  
And Chemical Properties

In this study, porous ceramics having cordierite crystalline phases were made from kaolin, talc and α-alumina at 1200 °C for 1 h. Coal powders and starch were used as pore-forming materials, respectively. Physical and chemical properties and microstructure of two samples were studied. The study results indicate that the pores of starch samples are homogeneous. Compared to coal powders samples, the porosity of starch samples is higher, but the bending strength is lower than that of coal powders samples.

Analysis on Causes of Corrosion in the Sleeve Joint of Certain Offshore Pipeline System

2015 ◽  
Vol 1088 ◽  
pp. 697-700
Author(s):  
Hong Wang ◽  
Xian He Liu
Keyword(s):  
Flow Field ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Pipeline System ◽  
Corrosion Mechanism ◽  
Physical And Chemical Properties ◽  
Offshore Pipeline ◽  
Field Action ◽  
Physical And Chemical ◽  
And Chemical Properties

Leakage was found in certain oilfield offshore pipeline system and investigation results showed that the cause of the leak was corrosion perforation in the sleeve joints of pipeline system. In order to avoid the leak occurring again, it was necessary to analyze corrosion mechanism of the sleeve joints. Macro and micro analyze, test on physical and chemical properties and microstructure, XRD analysis on corrosion products was accomplished on the sleeve joints. Results obtained from analysis and test show that corrosion was stronger because there are some CO2 and H2S in the pipeline together. Corrosion perforation was brought by flow velocity suddenly increase and turbulent flow and flow field action.

scholarly journals Characteristics of Kaolin Clay on Alluvial Formation Subdistrict Mataraman Based on Physical Properties and Chemical Properties

2019 ◽  
Vol 280 ◽  
pp. 03009
Author(s):  
Annisa ◽  
Marselinus Untung Dwiatmoko ◽  
Uyu Saismana ◽  
Rizal Maulanai
Keyword(s):  
Physical Properties ◽  
Analytical Method ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Kaolin Clay ◽  
Chemical Characteristics ◽  
Clay Deposit ◽  
Physical And Chemical ◽  
Alluvial Formation ◽  
And Chemical Properties

The kaolin clay deposit is found in the Quarter AlluviumFormation (Qa) which is located in the Mataraman Subdistrict and aroundBanjar Regency, South Kalimantan Province, with a monoclinic geologicalstructure. The purpose of this study was to identify types of clay mineralsand physical and chemical characteristics. The analytical method used inthis study is the method of analysis of physical properties and chemicalproperties The study area clay has physical characteristics, elastic clay, easy to form with a mixture of sand and cricket such as quartzite andwhite. Based on the results of XRD analysis, the types of clay mineralsfound were Kaolinit, Mica and Quartz, the chemical requirements of theclay of the study area could be used as material for making ceramics and pottery.

scholarly journals Influence of Nano-SiO2on the Consistency, Setting Time, Early-Age Strength, and Shrinkage of Composite Cement Pastes

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yu Chen ◽  
Yi-fan Deng ◽  
Meng-qiang Li
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Raw Materials ◽  
Setting Time ◽  
Active Role ◽  
Early Age ◽  
Cement Pastes ◽  
Composite Cement ◽  
Setting Times ◽  
Physical And Chemical

The study outlined the raw materials and mix proportions to prepare composite cement pastes with the addition of silica-based micro- and nanoparticles. The effects of amorphous nano-SiO2on the early-age properties, including the consistency, setting time, early-age strength, and chemical and autogenous shrinkages, were investigated. Under the condition of the same dosage of superplasticizer used, the consistency of cement paste with nano-SiO2is higher than that with silica fume. Significant reductions of the initial and final setting times are observed especially for nano-SiO2addition groups, and the time difference between the initial and final setting times goes up with the increasing proportions of nano-SiO2. The addition of nano-SiO2is more helpful to the improvement of early-age strengths of the paste with or without fly ash admixed than silica fume additive for the same mass proportion. Both the chemical and autogenous shrinkages of cement paste develop with the increasing amount of micro- or nanolevel silica particles; however, nano-SiO2plays a more active role than silica fume in inspiring early-age shrinkage. The physical and chemical mechanisms of nano-SiO2in cement paste are also discussed.

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