scholarly journals Hydration of Cement in the Presence of Biocidal Modifiers Based on Metal Hydrosilicates

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 292
Author(s):  
Anna N. Grishina ◽  
Evgenij V. Korolev ◽  
Vitaliy A. Gladkikh
Keyword(s):  
Silicic Acid ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Composite Binder ◽  
Modifying Additives ◽  
Barium Copper ◽  
Calcium Hydrosilicates ◽  
Cement Binder

This article presents the results of a study of the characteristics of hydration and properties of a composite biocidal cement binder containing hydrosilicates of barium, copper or zinc. It was found that copper hydrosilicates block hydration processes, and when zinc hydrosilicates are used, the rate of hydration is determined by the content of silicic acid. The limiting concentrations of biocidal modifiers have been established: zinc hydrosilicates—no more than 4% and copper hydrosilicates—no more than 0.5%, which are advisable to use for the manufacture of a biocidal composite binder. It is shown that modifying additives slow down the setting time, the amount of tricalcium silicate in cement stones increases, and their strength for some compositions decreases. Active binding of portlandite with the formation of calcium hydrosilicates occurs when the content of zinc hydrosilicates is 2%, which leads to an increase in the strength of the materials.

scholarly journals COMPOSITE BINDERS BASED ON CONCRETE SCRAP

2020 ◽  
pp. 8-18
Author(s):  
A. Ahmed ◽  
R. Lesovik ◽  
S. Al Mamouri ◽  
T. Gunchenko
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Setting Time ◽  
Normal Density ◽  
Composite Binder ◽  
Construction Products ◽  
Normative Documentation ◽  
Optimal Strength ◽  
Vibration Mill

The object of research is composite binders obtained from concrete scrap of destroyed buildings and structures for the production of various construction products and structures. Fractions of concrete scrap of 0,0–0,16 mm and 0,16–0,315 mm are used, since x-rayphase analysis of various fractions of concrete scrap shows that these fractions have the highest content of non-hydrated particles of alite and belite. The influence of the specific surface area on the normal density of cement dough and the setting time of binders is established. Comparative physical and mechanical indicators of hardening of binders with different specific surfaces indicate that the most stable results with a uniform increase in strength is the composition of a binder with a specific surface of 964 m2 / kg, with an increase in strength from 2 to 7 days – 27 % and from 7 to 28 days – 21 %. This binder is characterized by optimal strength at the age of 28 days – 25,5 MPa. With a specific surface of 964 m2/kg, the best conditions are created for the formation of the primary frame and its further fouling with various calcium crystalline hydrates, which ensure optimal density and strength. This composite binder has a specific surface area of 964 m2/kg and is more energyefficient. Composite binders obtained in a vibration mill from concrete scrap fractions (0,0–0,16 and 0,16–0,315 mm) meet the requirements of normative documentation on setting time and physico-mechanical parameters, which allows to recommend them for use as binders in the production of construction products and structures for various purposes.

scholarly journals Development of a Zero-Cement Binder Using Slag, Fly Ash, and Rice Husk Ash with Chemical Activator

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
M. R. Karim ◽  
M. F. M. Zain ◽  
M. Jamil ◽  
F. C. Lai
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Setting Time ◽  
Time Flow ◽  
Alumina Gel ◽  
Cement Binder ◽  
Increasing Demand ◽  
Chemical Activator

The increasing demand and consumption of cement have necessitated the use of slag, fly ash, rice husk ash (RHA), and so forth as a supplement of cement in concrete construction. The aim of the study is to develop a zero-cement binder (Z-Cem) using slag, fly ash, and RHA combined with chemical activator. NaOH, Ca(OH)2, and KOH were used in varying weights and molar concentrations. Z-Cem was tested for its consistency, setting time, flow, compressive strength, XRD, SEM, and FTIR. The consistency and setting time of the Z-Cem paste increase with increasing RHA content. The Z-Cem mortar requires more superplasticizer to maintain a constant flow of110±5% compared with OPC. The compressive strength of the Z-Cem mortar is significantly influenced by the amounts, types, and molar concentration of the activators. The Z-Cem mortar achieves a compressive strength of 42–44 MPa at 28 days with 5% NaOH or at 2.5 molar concentrations. The FTIR results reveal that molecules in the Z-Cem mortar have a silica-hydrate (Si-H) bond with sodium or other inorganic metals (i.e., sodium/calcium-silica-hydrate-alumina gel). Therefore, Z-Cem could be developed using the aforementioned materials with the chemical activator.

Improving Construction Engineering Properties of Soils Stabilized by a Cement Binder with Techno-Genic Products

2020 ◽  
Vol 299 ◽  
pp. 26-31
Author(s):  
Margarita A. Goncharova ◽  
Konstantin A. Korneev ◽  
German S. Dedyaev
Keyword(s):  
Engineering Properties ◽  
Strength Gain ◽  
Metallurgical Waste ◽  
Optimum Amount ◽  
Composite Binder ◽  
Construction Engineering ◽  
Soil Cement ◽  
Cement Binder ◽  
Soil Hardening ◽  
Furnace Slag

The article considers the method of stabilizing roadbed soils by introducing metallurgical waste in the structure of the composite binder. It was established during the analysis and experimental research that construction engineering properties are improved as a result of the method. The article provides the obtained results of laboratory tests. The optimum amount of ground blast furnace slag as a component to replace part of Portland cement in a soil cement mix is determined. The dependence of strength gain on the hardening time at different proportions of the composite binder is given. The efficiency of the considered method of soil hardening is estimated.

Physical, mechanical, and durability properties of gypsum–Portland cement–natural pozzolan blends

2001 ◽  
Vol 28 (3) ◽  
pp. 375-382 ◽  
Author(s):  
Adnan Çolak
Keyword(s):  
Portland Cement ◽  
Water Absorption ◽  
Setting Time ◽  
Strength Loss ◽  
Natural Pozzolan ◽  
Durability Properties ◽  
Gypsum Content ◽  
Mechanical Durability ◽  
Binder Ratio ◽  
Cement Binder

This paper deals with the effect of gypsum–Portland cement and gypsum–Portland cement–natural pozzolan ratios on the physical, mechanical, and durability properties of gypsum–Portland cement–natural pozzolan blends. The results indicate that the setting time of these paste decreases with the increase of gypsum content in the mixture, ranging from 8 to 11 min. The addition of superplasticizer increases the setting time from approximately 11 to 35 min. This increase is greatly dependent on the plasticizer admixture dosage. These blends show a kinetic of capillary water absorption very similar to that of the Portland cement binder. Sorptivity is strongly influenced by the type of binder, binder composition and water–binder ratio. Porosity of blended gypsum binders ranges from 12% to 37%. Their water absorption is high, reaching 27% in the blends with a greater proportion of gypsum. The gypsum–Portland cement blends themselves possess good water resistance, which is further enhanced by the addition of natural pozzolan and superplasticizer. The water-cured blends with the composition of 41:41:18 (gypsum : Portland cement : natural pozzolan) and 41:41:18S1 (gypsum : Portland cement : natural pozzolan : 1% superplasticizer) offer a compressive strength of approximately 20 MPa at room temperature. These blends give excellent properties retention after aging in water at 20°C for 95 days. Their good resistance to water decreases as the gypsum content in the mixture is raised. However, the strength loss for the gypsum–Portland cement–natural pozzolan blends is generally less than that observed for the gypsum binder.Key words: gypsum, Portland cement, natural pozzolan, physical, mechanical, durability.

scholarly journals Effects of Highly Crystalized Nano C-S-H Particles on Performances of Portland Cement Paste and Its Mechanism

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 816
Author(s):  
Yuli Wang ◽  
Huijuan Lu ◽  
Junjie Wang ◽  
Hang He
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Strength Development ◽  
Early Age ◽  
Hydration Products ◽  
X Ray ◽  
Early Strength ◽  
Portland Cement Paste

In order to improve the early age strength of ordinary Portland cement-based materials, many early strength agents were applied in different conditions. Different from previous research, the nano calcium silicate hydrate (C-S-H) particles used in this study were synthesized through the chemical reaction of CaO, SiO2, and H2O under 120 °C using the hydrothermal method, and the prepared nano C-S-H particles were highly crystalized. The influences of different amounts of nano C-S-H particles (0%, 0.5%, 1%, 2% and 3% by weight of cement) on the setting time, compressive strength, and hydration heat of cement paste were studied. The hydration products and microstructure of the cement paste with different additions of nano C-S-H particles were investigated through thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), and scanning electron microscope (SEM) tests. The results show that the nano C-S-H particles could be used as an early strength agent, and the early strength of cement paste can be increased by up to 43% through accelerating the hydration of tricalcium silicate (C3S). However, the addition of more than 2% nano C-S-H particles was unfavorable to the later strength development due to more space being left during the initial accelerated hydration process. It is suggested that the suitable content of the nano C-S-H particles is 0.5%−1% by weight of cement.

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.

Products of Reaction between Barium Chloride and Sodium Hyrdosilicates: Examination of Composition

2014 ◽  
Vol 1040 ◽  
pp. 347-350 ◽  
Author(s):  
Anna Nikolaevna Grishina ◽  
Evgeniy Valerjevich Korolev ◽  
Anton Borisovich Satyukov
Keyword(s):  
Ir Spectroscopy ◽  
Silicic Acid ◽  
Barium Carbonate ◽  
Barium Chloride ◽  
Main Reaction ◽  
Joint Analysis ◽  
Endothermic Effect ◽  
Main Reaction Product ◽  
Curing Agent ◽  
Calcium Hydrosilicates

One of the promising directions of quality improvement of building materials (based on various binders) is to use hydrosilicates of calcium and barium. In particular, it is known that the application of calcium hydrosilicates can improve the compression strength in two or three times; the fracture toughness can be increased in two times and more. Prospects of using barium hydrosilicates in cement systems are due to the similarity of the chemical composition (with calcium hydrosilicates) and advantages of barium cements compared to traditional cements. It is advisable to synthesize the barium hydrosilicates by means of low-temperature technology. To investigate the influence of the curing agent (barium chloride) to the properties of the reaction products in the present study the IR spectroscopy and differential scanning calorimetry (DSC) are used. Analysis of the results allowed to state that the main reaction product is a crystalline silicate phase. Reducing the amount of curing agent leads to an increase of the content of silicic acid. DSC results show that dehydration of barium hydrosilicates takes place in two stages. It is typical for systems BaO•SiO2•6H2O. Increasing the content of silicic acid is accompanied by an endothermic effect in temperature range of 120...130 °C. Joint analysis of the results of IR spectroscopy and DSC leads to the conclusion that there is a reaction of barium carbonate and silicic acid. In general case, reduction of the amount of the curing agent contributes to increase of content of the silica acid and barium carbonate. Therefore, it is advisable to use compositions prepared with reduced amount of BaCl2 in systems capable of interacting with the silica acid and forming the insoluble products.

scholarly journals Physicochemical Properties and Dentin Bond Strength of a Tricalcium Silicate-Based Retrograde Material

2017 ◽  
Vol 28 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Camila de Paula Telles Pires Lucas ◽  
Raqueli Viapiana ◽  
Roberta Bosso-Martelo ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
Josette Camilleri ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Physicochemical Properties ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Final Setting Time ◽  
Root Canal Dentin ◽  
Post Hoc ◽  
Push Out

Abstract The aim of this study was to evaluate the physicochemical properties and the apical dentin bond strength of the tricalcium silicate-based Biodentine in comparison to white MTA and zinc oxide eugenol-based cement (ZOE). Setting time and radiopacity were evaluated according to ISO 6876:2012 specification. Final setting time, compressive strength and pH were also assessed. Material’s bond strength to the apical root canal dentin was measured by the push-out assay. Data were analyzed by ANOVA and Tukey-Krammer post-hoc test. Biodentine presented the shortest initial (16.2±1.48 min) and final setting time (35.4±5.55 min). Radiopacity of Biodentine (2.79±0.27 mmAl) does not agree with ISO 6876:2012 specifications. On the other hand, Biodentine showed higher compressive strength after 21 days (37.22±5.27 MPa) and higher dentin bond strength (11.2±2.16 MPa) in comparison to white MTA (27.68±3.56 MPa for compressive strength and 2.98±0.64 MPa for bond strength) (p<0.05). Both MTA and Biodentine produced an alkaline environment (approximately pH 10) (p>0.05) compared to ZOE (pH 7). It may be concluded that Biodentine exhibited faster setting, higher long-term compressive strength and bond strength to the apical dentin than MTA and ZOE.

scholarly journals Physicochemical Properties and Antibiofilm Activity of Tricalcium Silicate Cement and its Association with Cetrimide

2021 ◽  
pp. 333-341
Author(s):  
Giulia Bueno Rodrigues ◽  
Mario Tanomaru-Filho ◽  
Gisselle Moraima Chavez-Andrade ◽  
Fernanda Ferrari Esteves Torres ◽  
Juliane Maria Guerreiro-Tanomaru
Keyword(s):  
Physicochemical Properties ◽  
Zirconium Oxide ◽  
Setting Time ◽  
Mass Gain ◽  
Positive Control ◽  
Tricalcium Silicate ◽  
The Other ◽  
Antibiofilm Activity ◽  
Setting Times ◽  
Root Dentin

Cetrimide (CTR) is a cationic surfactant detergent with antimicrobial and antibiofilm activity. The aim of this study was to evaluate setting time, pH, solubility and antibiofilm activity of tricalcium silicate cement (TSC) with zirconium oxide (ZrO2) and its association with 0.2 and 0.4% cetrimide. Initial and final setting times (IST and FST) were assessed based on ISO-6876. pH was evaluated at periods of 1,3,7,14 and 21 days. Solubility was analyzed by weight loss. A modified direct contact test (MDCT) on the biofilm of Enterococcus faecalis formed on bovine root dentin blocks was performed, after 6 hours of manipulation and 15 hours of contact time. The analysis was performed by UFC mL ­¯¹ counting. The data were analyzed by ANOVA and Tukey’s tests (α=0.05). Higher IST was observed for TSC/ZrO2+CTR in both concentrations than for TSC/ZrO2 and lower FST for TSC/ZrO2+0.4% CTR (p<0.05). On day 1, TSC/ZrO2 showed lower pH than the associations with CTR (p<0.05). During the other periods, TSC/ZrO2 and associations promoted similar alkalinization (p>0.05). All materials exhibited increased mass. TSC/ZrO2+CTR 0.4% had lower mass gain than the other materials (p<0.05). The highest antibiofilm activity was observed for TSC/ZrO2+CTR in both concentrations, when compared with the positive control (p<0.05). In conclusion, CTR exhibited potential to promote greater antibiofilm activity to tricalcium silicate cement, without harming its physicochemical properties of setting time, pH and solubility.

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