scholarly journals Influence of Inertia and Low Active Mineral Admixture on Strength and Microstructure of Cement-Based Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Meijuan Rao ◽  
Wan Tang ◽  
Wei Zhou ◽  
Yaning Kong ◽  
Shuhua Liu
Keyword(s):  
Fly Ash ◽  
Early Stage ◽  
Heat Of Hydration ◽  
Mineral Admixture ◽  
Limestone Powder ◽  
Mineral Admixtures ◽  
Inert Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials

Cement-based materials were investigated by comparing the strength and microstructure of pastes and mortar containing limestone powder or low quality fly ash. The compressive strength of the mortar at 28 and 90 d was examined whose microstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, and differential thermal analysis (TG-DTA). The results indicated that the strength of mortar decreased with increasing mineral admixtures. The limestone powder mainly acted as inert filler and hardly took part in the chemical reaction. Low quality fly ash may accelerate the formation of hydration products in samples with more chemically bonded water. This further resulted in a higher degree of cement hydration and denser microstructure, while the overall heat of hydration was reduced. At the early stage of hydration, low quality fly ash can be considered as an inert material whereas its reactivity at the later stage became high, especially for ground low quality fly ash.

Influence of Fly Ash on Thaumasite Form of Sulfate Attack in Cement-Based Materials

2013 ◽  
Vol 377 ◽  
pp. 74-79
Author(s):  
Chang Cheng Li ◽  
Fu Jie Jia ◽  
Xu Nan Wu
Keyword(s):  
Fly Ash ◽  
Activity Index ◽  
Early Stage ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Minor Role ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials ◽  
A Minor

A low temperature sulfate attack research was carried out to investigate the effects of fly ash on thaumasite form of sulfate attack (TSA) in cement-based materials. Cement-limestone-fly ash samples were immerged in 5% magnesium sulfate solution at (5±2) oC. The appearance of samples was observed, and strength was also tested. Besides, the corrosion products were analyzed by infrared spectrum (IR) and X-ray diffraction (XRD) methods. Cement was equally replaced by fly ash with 20%, 30%, and 50% proportions. The results show that: Effects of fly ash on TSA were closely related to the composition, content and fineness of fly ash. Fly ash with an activity index larger than 80% could improve the resistance to TSA in cement-based materials when the replacement reached 50% while fly ash only played a minor role in early stage with 20%-30% content.

scholarly journals Influence of Mineral Admixtures on Corrosion Inhibition Effect of Nitrites

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Mengna Yang ◽  
Junzhe Liu ◽  
Hui Wang ◽  
Yushun Li ◽  
Yanhua Dai ◽  
...  
Keyword(s):  
Fly Ash ◽  
Corrosion Inhibition ◽  
Ion Concentration ◽  
Mineral Admixtures ◽  
X Ray Diffraction ◽  
Nitrite Ion ◽  
X Ray ◽  
Inhibition Effect ◽  
Diffraction Patterns ◽  
Micro Analysis

Chemical quantitative analysis of effective anticorrosion component and micro-analysis of hydration products of fly ash and slag on the influence of the nitrites corrosion inhibition was studied by the free nitrite ion concentration and X-ray diffraction pattern. The free nitrite ion concentration was used to describe the corrosion inhibition effect of nitrites. And the X-ray diffraction patterns were used to analyze the adsorption properties. The research results show that fly ash and slag were beneficial for improving the corrosion inhibition effect of nitrites. Cement-based materials with slag at low content presented high free nitrite ion concentration, but the addition of low content of fly ash harmed the corrosion inhibition effect of nitrites. The specimens incorporated with both fly ash and slag can reach the highest free nitrite ion concentration when the compounding proportion was 1:1. It was concluded that the extent of mineral admixtures of the corrosion inhibition effect of nitrites was affected by its type and content.

Accelerate Thaumasite Formation in Cement-Limestone Powder Paste by Internal Adding Method

2011 ◽  
Vol 250-253 ◽  
pp. 22-27 ◽  
Author(s):  
Chang Cheng Li ◽  
Yan Yao ◽  
Ling Wang
Keyword(s):  
Magnesium Sulfate ◽  
Sodium Sulfate ◽  
Calcium Sulfate ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials ◽  
Internal Sulfate Attack

Cement-limestone powder pastes added with 10% magnesium sulfate, sodium sulfate, and calcium sulfate respectively were stored in water at (5±2) °C to accelerate thaumasite formation. The pastes were inspected visually at intervals. And the formation of thaumasite was identified and confirmed by X-ray diffraction (XRD), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The results show that internal adding sulfate in cement-limestone powder paste is an efficient way to accelerate thaumasite formation, and the accelerated effect is magnesium sulfate> sodium sulfate> calcium sulfate. Cement-limestone paste containing 10% magnesium sulfate totally turns into grey-white mushy materials after 6 months immersion, and products are mainly thaumasite and gypsum. In addition, the amount of thaumasite increases along with time of internal sulfate attack in 15 months. XRD, IR, and NMR are powerful and reliable tools for identification of thaumasite in cement-based materials.

Research on Polypropylene Fiber and Mineral Admixtures on Fluidity of Cement-Based Materials

2011 ◽  
Vol 328-330 ◽  
pp. 1301-1304
Author(s):  
Xue Fei Li ◽  
Tao Guo
Keyword(s):  
Fly Ash ◽  
Cement Mortar ◽  
Polypropylene Fiber ◽  
Maximum Flow ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Polypropylene Fibers ◽  
Intensity Level ◽  
Reticular Fibers ◽  
Cement Based Materials

The purpose of this paper is based on the cement-based materials by adding fibers and mineral admixtures for composite, to cement the improvement of liquidity. Experiment with the intensity level of 42.5 ordinary portland cement, by adding polypropylene fibers, slag and fly ash cement mortar as a mineral admixture, the production of cement mortar matrix for the test, were conducted on a variety of mix Fluidity test. Experiments show that the addition of polypropylene fiber is not conducive to the mobility of mortar, especially monofilament fiber was more obvious than the reticular fibers. To join the slag, fly ash, mortar fluidity increased, indicating that slag and fly ash added to improve the workability of cement-based materials. When the fiber content reaches the maximum degree of maximum flow, indicating that slag, fly ash and polypropylene fibers will increase the combined effect of fluidity value. This innovation is obtained by adding fiber cement-based materials for toughening effect, with the use of mineral admixture can improve the overall performance of cement based materials, with further research and promotion value.

Mechanical Characteristics of Concrete Exposed to External Flexural Load, De-Icing Salt and Freeze-Thaw Cycles

2011 ◽  
Vol 250-253 ◽  
pp. 33-39
Author(s):  
Xiao Lu Yuan ◽  
Bei Xing Li ◽  
Shang Chuan Zhao ◽  
Shi Hua Zhou
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Ordinary Portland Cement ◽  
Mechanical Characteristics ◽  
Concrete Strength ◽  
Mineral Admixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Freeze Thaw

This paper investigates mechanical characteristics of concrete exposed to external flexural load, de-icing salt and freeze-thaw cycles. Concrete specimens made with ordinary Portland cement or ordinary Portland cement incorporating fly ash with the replacement of 10% or 20%, or 0.7/10000 air-entraining agent and 20% fly ash, or ground blast furnace slag with the replacement of 15% or 30%, were made and exposed to flexural load, freeze-thaw and de-icing salt environment. Mechanical properties of concrete including compressive strength and flexural strength were measured. Phase composition of samples was determined by means of x-ray diffraction (XRD). Results indicate that increasing flexural stress ratios reduced compressive strength and flexural strength of concrete, and presented higher improvement of mineral admixtures in concrete strength. Incorporation of mineral admixtures and air-entraining agent decreased the loss of concrete strength. X-ray diffraction analysis showed the presence of abundant calcium chloroaluminate and ettringite in paste samples.

scholarly journals A Research on Durability Degradation of Mineral Admixture Concrete

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1752
Author(s):  
Xupeng Chen ◽  
Zhuowen Sun ◽  
Jianyong Pang
Keyword(s):  
Fly Ash ◽  
Circle Method ◽  
Mineral Admixture ◽  
X Ray Diffraction ◽  
Complex Ions ◽  
Sulfate Ions ◽  
X Ray ◽  
Relational Analysis ◽  
Grey Relational ◽  
Compressive Tests

In order to study the degradation laws and mechanisms of admixture concretes with single-added SO42− and composite of Mg2+ and SO42−, respectively, the durability tests were conducted on three types of mineral admixture concretes (concretes with single-added metakaolin (MK), single-added ultra-fine fly ash (UFA), and composite of metakaolin and ultra-fine fly ash (MF), and one reference concrete. In these tests, the 10% Na2SO4 solution and the 10% MgSO4 solution were used as the erosion medium, and the drying-wetting circle method was applied. It can be seen from the compressive tests and grey relational analysis that the MK admixture can improve the anti-Na2SO4-erosion capability of the concrete significantly, but weaken its anti-MgSO4-erosion capability; the UFA admixture can improve both the anti-Na2SO4-erosion and the anti-MgSO4-erosion capability of the concrete; and the composite admixture has superimposed effects and can enhance erosion resistance against these two erosion mediums. The phase composition and the changes of the macro morphology and the micro structure during the erosion process caused by mono sulfate ions and complex ions has been observed through X-ray diffraction (XRD), FTIR spectrum (FTIR), and scanning electron microscope (SEM), based on which it was determined that the erosion of single-added SO42− ions can produce erosive outputs of ettringite, gypsum, and mirabilite in the concrete, and cause corner scaling or deformation. Mg2+ and SO42− reacted in the concrete and produced brucite, M-S-H, ettringite, and gypsum, etc. The erosion of complex ions can cause scaling of the cement mortar and aggregate from the surface or the desquamation of corners.

Quantitative X-ray diffraction of free, not chemically bound water with the PONKCS method

2018 ◽  
Vol 51 (6) ◽  
pp. 1535-1543 ◽  
Author(s):  
Sebastian Scherb ◽  
Nancy Beuntner ◽  
Karl-Christian Thienel ◽  
Jürgen Neubauer
Keyword(s):  
Fly Ash ◽  
Bound Water ◽  
Free Water ◽  
Limestone Powder ◽  
X Ray Diffraction ◽  
Water Addition ◽  
Continuous Increase ◽  
X Ray ◽  
Wide Range ◽  
Scattering Contribution

The free water in calcined phyllosilicate–water mixtures exhibits a distinctly different behaviour in its X-ray amorphous scattering contribution as opposed to fly ash– or limestone powder–water mixtures. While fly ash and limestone powder yield a continuous increase in the scattering contribution when water is added, the scattering contribution stagnates for calcined phyllosilicates over a wide range of water addition. There is a direct correlation between the consistency of the sample and the X-ray amorphous scattering contribution caused by the water. The same correlation can also be found in in situ X-ray diffraction measurements of hydrating systems. As long as the sample has a pasty consistency, the scattering contribution of the water decreases with progressive reaction. After the transition from fresh paste to final set, there is no further reduction of the X-ray amorphous scattering contribution caused by the free water, which means that the free water cannot be quantified correctly from this point in time.

scholarly journals Physical and chemical effects of limestone filler on the hydration of steam cured cement paste and mortar

2020 ◽  
Vol 10 (2) ◽  
pp. 191-205
Author(s):  
Mohmmad Aqel ◽  
Daman Panesar
Keyword(s):  
Thermal Analysis ◽  
Material Properties ◽  
Dilution Effect ◽  
Heat Of Hydration ◽  
Inert Material ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
X Ray ◽  
Chemical Effects ◽  
Physical And Chemical

The aim of the paper is to decouple the physical and chemical effects of limestone filler (LF), when used as a cement replacement. The effects were decoupled using LF and a chemically inert material (brucite Mg(OH)2). Paste, and mortar specimens were steam cured for 16 hours at 55°C. The heat of hydration, thermal analysis, x-ray diffraction, and compressive strength, were evaluated at 16 hours and at 28 days. LF can adversely affect the properties through dilution effect. However, heterogeneous nucleation compensates for the dilution effect at 16 hours while the production of mono-carboaluminate compensates for the dilution effect at 16 hours and 28 days. The study could be broadened by considering a wider temperature range. The originality lies in the method of decoupling the physical and chemical effects. Measurable effects of the physical and chemical contribution of LF are evident on the mechanical and transport material properties.

scholarly journals Study on Strength and Microstructure of Cement-Based Materials Containing Combination Mineral Admixtures

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Meijuan Rao ◽  
Jianpeng Wei ◽  
Zhiyang Gao ◽  
Wei Zhou ◽  
Qiaoling Li ◽  
...  
Keyword(s):  
Testing Machine ◽  
Steel Slag ◽  
Pozzolanic Reaction ◽  
Mineral Admixture ◽  
Limestone Powder ◽  
Mineral Admixtures ◽  
Strength Development ◽  
Hydration Products ◽  
Cement Based Materials ◽  
Aggregate Effect

The compressive strength of complex binders containing two or three blended mineral admixtures in terms of glass powder (GP), limestone powder (LP), and steel slag powder (SP) was determined by a battery solution type compressive testing machine. The morphology and microstructure characteristics of complex binder hydration products were also studied by microscopic analysis methods, such as XRD, TG-DTA, and SEM. The mechanical properties of the cement-based materials were analyzed to reveal the most appropriate mineral admixture type and content. The early sample strength development with GP was very slow, but it rapidly grew at later stages. The micro aggregate effect and pozzolanic reaction mutually occurred in the mineral admixture. In the early stage, the micro aggregate effect reduced paste porosity and the small particles connected with the cement hydration products to enhance its strength. In the later stage, the pozzolanic reaction of some components in the complex powder occurred and consumed part of the calcium hydroxide to form C-S-H gel, thus improving the hydration environment. Also, the produced C-S-H gel made the structure more compact, which improved the structure’s strength.

Physical and Mechanical Properties of Cement Paste Were Used Partially with Fly Ash and Kaolin Waste

2017 ◽  
Vol 866 ◽  
pp. 199-203
Author(s):  
Chidchanok Chainej ◽  
Suparut Narksitipan ◽  
Nittaya Jaitanong
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Partial Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lime Water ◽  
Diffraction Patterns ◽  
Iron Mold

The aims of this research were study the microstructures and mechanical properties for partial replacement of cement with Fly ash (FA) and kaolin waste (KW). Ordinary Portland cement were partially replaced with FA and KW in the range of 25-35% and 10-25% by weight of cement powder. The kaolin waste was ground for 180 minutes before using. The specimen was packing into an iron mold which sample size of 5×5×5 cm3. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the incubation lime water bath at age of 3 days. After that the specimens were dry cured with plastic wrap at age of 3, 7, 14 and 28 days. After that the compounds were examined by x-ray diffraction patterns (XRD) and the microstructures were examined by scanning electron microscopy (SEM). The compressive strength was then investigated.

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