The chemical and phase composition of Portland cement

2007 ◽  
pp. 92-117
Keyword(s):  
Phase Composition ◽  
Portland Cement

The Effect of Boron and its Compounds on Setting of Portland Cement

2014 ◽  
Vol 1000 ◽  
pp. 16-19 ◽  
Author(s):  
Jiří Kratochvíl ◽  
Tomáš Opravil ◽  
Pavel Diviš
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Portland Cement ◽  
Boric Acid ◽  
Cement Paste ◽  
Kinetics Of

The aim of this work is to study the influence of boron and its compounds, boric acid and borax, on the hydration of Portland cement. The samples – cement paste modified by the addition of boron, borax and boric acid in different concentrations were prepared. The results are obtained from the evaluation of calorimetric curves, mechanical properties and phase composition. The goal is to describe the kinetics of targeted retarded process of hydration and to find such addition which would suspend the setting of boron modified system entirely. The comparison of effects of each boron-containing compound is based on its concentration and on its kind.

The Increase of Hydration Activity of Portland Cement by Additives of Crystalline Hydrates

2019 ◽  
Vol 974 ◽  
pp. 195-200
Author(s):  
Yury R. Krivoborodov ◽  
Svetlana V. Samchenko
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Cement Hydration ◽  
Bound Water ◽  
Cement Stone ◽  
Pulsation Apparatus ◽  
Rotary Pulsation Apparatus ◽  
Calcium Hydrosilicates ◽  
Crystalline Hydrates

The article presents the results of a study of the effect of synthesized microdisperse additives of crystalline hydrates based on calcium sulfoaluminates on the properties of cement stone. The effectiveness of the use of a rotary pulsation apparatus (RPA) to obtain microdispersed additives is identified. The possibility of accelerating the hardening of cement stone by entering microdispersed additives into its composition is shown. It has been established that in the presence of microdispersed additives of crystalline hydrates in the cement stone, the phase composition of hydrate tumors changes, the amount of calcium hydrosilicates and ettringite increases, the porosity decreases and the strength of the cement stone increases. This provision is confirmed by the increase in the degree of cement hydration, the amount of bound water in all periods of hardening of the stone. It is proposed to use microdisperse additives, which play the role of primers for the crystallization of ettringite and calcium hydrosilicates, to increase the strength of cement stone in the early stages of hardening.

Preparation and its Application Performance of Backfilling Cementation Material Based on Blast Furnace Slag

2011 ◽  
Vol 239-242 ◽  
pp. 2389-2394
Author(s):  
Shu Gang Hu ◽  
Hai Li Niu ◽  
Xian Jun Lu
Keyword(s):  
Blast Furnace ◽  
Phase Composition ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Superior Performance ◽  
Application Performance ◽  
Potential Activity ◽  
Furnace Slag ◽  
Optimal Formula

The blast-furnace slag （BFS）has been characterized by chemical and phase composition to evaluate its hydration reactivity. It has high potential activity for its glassy structure, so its use to prepare new filling cementation material is possible. New backfilling cementation material composition has been formulated and optimized by activation of BFS. The optimal formula of new backfilling cementation material SL(Slag activated by lime) and SLG(Slag activated by lime and desulfurization gypsum) was 87% BFS, 13% lime and 78.4% BFS, 11.8% lime, 9.8% desulfurization gypsum respectively. Finally, the feature of application performance was analyzed through comparison between new cementation material and ordinary Portland cement with paste and sand mortar experiment. The result showed that material SL and SLG have superior performance to ordinary Portland cement used to mining cemented filling.

Chemical Changes Occurring During the Early Hydration of PFA-OPC Mixtures

1985 ◽  
Vol 65 ◽  
Author(s):  
K. Luke ◽  
F. P. Glasser
Keyword(s):  
Phase Composition ◽  
Steady State ◽  
Fly Ash ◽  
Portland Cement ◽  
Aqueous Phase ◽  
Early Hydration ◽  
Chemical Changes ◽  
Class F

ABSTRACTThe course of the initial set reactions of Portland cement-PFA blends is markedly influenced by the presence of fly ash. Data are presented on the effect of two Class F PFA materials blended with cement in 30:70 ratio. Selected analyses of the aqueous phase compositions at lh to 336h are presented. During the first 6h a nearly steady state aqueous phase composition is achieved with respect to Na, K and Ca concentrations. Following a renewed burst of hydration activity, Ca decreases rapidly in the interval 6–24 h while Na and K contents rise more gradually.

scholarly journals MICROSCOPIC AND PHASE ANALYSIS OF CEMENT PASTE CONTAINING WASTE MICRONIZED MARBLE POWDER

2018 ◽  
Vol 15 ◽  
pp. 94-98
Author(s):  
Zdeněk Prošek ◽  
Pavel Tesárek ◽  
Jan Trejbal
Keyword(s):  
Electron Microscopy ◽  
Phase Composition ◽  
Portland Cement ◽  
Phase Analysis ◽  
Cement Paste ◽  
Reference Sample ◽  
Hydration Process ◽  
Cement Composites ◽  
Marble Powder ◽  
The Impact

The article focuses on the impact of waste marble powder on resulting cement composites. We investigate of influence waste marble powder on the hydration process and hence the resulting phase composition. The hydration process was investigated using calorimetry and phase composition of the resulting composite by electron microscopy. The results are compared with a reference sample composed of Portland cement.

scholarly journals CHANGES IN THE STRUCTURAL AND PHASE COMPOSITION OF CEMENT CONCRETE DURING MICROBIOLOGICAL CORROSION

2021 ◽  
Vol 6 (11) ◽  
pp. 106-113
Author(s):  
K. Strokin ◽  
D. Novikov ◽  
V. Konovalova ◽  
N. Kasiyanenko
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Portland Cement ◽  
Cement Stone ◽  
Cement Concrete ◽  
Microbiological Corrosion ◽  
Crystalline Phases ◽  
X Ray ◽  
Calcium Hydrosilicates ◽  
Black Mold

The article considers the change in the structural and phase composition of cement stone made of Portland cement of the CEM I 42.5 N brand in the process of bacterial and fungal corrosion during 6 months when humidified. The X-ray images of cement stone show peaks that characterize the non-hydrated components of Portland cement alite, belite, tricalcium aluminate, four-calcium aluminoferrite and gypsum. By the method of X-ray phase analysis, it is found that during microbiological corrosion, the content of all phases of cement stone decreases. The aspergillus niger van Tieghem fungi have a stronger effect on the structural and phase composition of cement stone. Fungal microorganisms destroy the crystalline phases and absorb amorphous phases – calcium hydrosilicates C-S-H (I) and C-S-H (II) and tobermorite. When bacteria Bacillus subtilis affects the cement stone, the content of the calcite phase increases, which is a product of corrosion, while the action of black mold reduces the intensity of CaCO3 peaks. A decrease in the content of low-base calcium hydrosilicates and ettringite, as well as other crystalline phases, leads to a decrease in the compressive strength of the cement stone. During 6 months of microbiological corrosion of cement concrete under conditions of constant wetting, the compressive strength decreases by about 35 %.

scholarly journals STUDY OF THE CHEMICAL INTERACTION OF GLASS FIBER WITH CEMENT HYDRATION PRODUCTS

2021 ◽  
Vol 5 (12) ◽  
pp. 119-125
Author(s):  
N. Bondarenko ◽  
D. Bondarenko ◽  
E. Evtushenko
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Glass Fiber ◽  
Chemical Interaction ◽  
Fluorescence Analysis ◽  
Hydration Products ◽  
Alumina Cement ◽  
X Ray ◽  
Negative Effect ◽  
The Stability

Reinforcement of concrete with fiberglass improves the performance properties of concrete. The object of the study is fiberglass concrete, where Portland cement or alumina cement is used as a binder, and silica fiberglass is used as a filler. The chemical and phase compositions of Portland cement and alumina cement have been studied. The influence of the products of hydration of Portland cement and alumina cement on the chemical resistance of glass fiber has been investigated. The phase composition of Portland cement and alumina cement after hydration is studied using X-ray phase analysis. It is revealed that the following phases are present in alumina cement: CaОAl2O3, MgОAl2O3, 12CaO•7Al2O3, 2CaO•Al2O3•SiO, the phase composition of Portland cement is Ca6Al2(SO4)3(OH)12•12H2O, Ca2,25(Si3O7,5(OH)1,5)•(H2O), Ca(OH)2, CaCO3. It has been found that when hydrated, Portland cement has a negative effect on fiberglass due to the presence of Ca(OH)2 in it. The phase composition of the alumina cement after hydration shows the absence of Ca(OH)2. The chemical composition of fiberglass is investigated using X-ray fluorescence analysis. The use of alumina cement when using non-alkali-resistant fiberglass in a composite material is substantiated. The study of the stability of fiberglass in the environment of cement drawing has been carried out. Studies have shown that KV-11 grade fiberglass interacted less with hydration products of alumina cement than with hydration products of Portland cement.

scholarly journals Plasma modification of construction mortar components, an efficient method of increasing their performance

Vestnik MGSU ◽  
2019 ◽  
pp. 548-558
Author(s):  
Anton Yu. Kalyadin ◽  
Grigor V. Nalbandyan ◽  
Vadim G. Soloviev ◽  
Anfisa A. Bogdanova ◽  
Valentin A. Ushkov
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Plasma Treatment ◽  
Granulometric Composition ◽  
Raw Materials ◽  
Setting Time ◽  
Silica Sand ◽  
Plasma Modification ◽  
Mechanical Parameters ◽  
Mixing Water

Introduction. The article considers the enhancement of physical and mechanical parameters of construction mortars used for recovering and repairing of building structures of communication collectors by using low-temperature nonequilibrium plasma. The study vindicated the expediency of treatment of construction mortar raw materials with LTNP to enhance their physical and mechanical parameters. The effect of plasma modification of raw materials on Portland cement phase composition, granulometric composition of the sand and mortar properties are analysed. The influence of multiplicity of silica sand and mixing water plasma treatment on the construction mortar strength is considered. Materials and methods. Cement-sand mortars are obtained from Portland cement of the CEM I 32.5N and CEM I 42.5N brands and silica sand with the fineness moduli of Mf = 0.32 and Mf = 0.63 and a separate fraction of less than 0.16 mm. Setting time and strength of the building mortars are defined according to GOST state standards in effect. Granulometric composition of the cement is explored by means of Analysette-22 particle size microanalyser, while ARL Optim’X spectrometer is used for studying phase composition of the cement stone, silica sand and cement-sand mortars. Results. It is determined that the plasma treatment of Portland cement reduces the grout normal consistency by 15 to 17 % and decreases its setting time by a factor of 3 to 4. Treatment of mixing water with the nonequilibrium low-temperature plasma removes its hardness, forming additional crystallization nuclei. The plasma-treated mixing water increases the curing rate of cement-sand mortars up to 50 % at the early stages of hardening and up to 30 % on the 28th day of hardening. Using plasma-treated silica sand decreases size of its particles and results in partial transition of the crystalline structure into the amorphous one. This reduces water demand of the sand by 10 to 18 %. Conclusions. The expedience of plasma treatment of raw materials to enhance the physical and mechanical properties of mortars is vindicated. Owing to the plasma modification of raw materials, quality and process characteristics of construction mortars are improved. The presented method of the plasma treatment of raw materials used to prepare the construction mortars is characterized with high degree of efficiency and convenience of application.

Effect of environmental pH values on phase composition and microstructure of Portland cement paste under sulfate attack

2021 ◽  
Vol 216 ◽  
pp. 108862
Author(s):  
Gaozhan Zhang ◽  
Cong Wu ◽  
Dongshuai Hou ◽  
Jun Yang ◽  
Daosheng Sun ◽  
...  
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Cement Paste ◽  
Sulfate Attack ◽  
Ph Values ◽  
Portland Cement Paste
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