Influence of Uranium on the Hydration Properties of the Cement Clinker Minerals

2021 ◽  
Vol 1036 ◽  
pp. 199-207
Author(s):  
Lang Du ◽  
Xiang Zhou ◽  
Liang Li ◽  
Yu Xiang Li ◽  
Xue Ma
Keyword(s):  
Waste Water ◽  
Hydration Product ◽  
Test Methods ◽  
Cement Clinker ◽  
Hydration Products ◽  
Hydration Properties ◽  
Simulated Waste

The influence of uranium simulated waste water on the hydration properties of the cement was studied by modern test methods such as TAM air, XRD, FTIR, and SEM-EDS. The results show that uranium can promote the hydration of mineral C3S, and inhibit the hydration of mineral C3A. By comparing scanning of hydration products, it was found that the existence of uranium significantly changed the morphology of clinker hydration products , but uranium had little effect on the type of clinker hydration product.

scholarly journals Comparative study on mechanisms for improving mechanical properties and microstructure of cement paste modified by different types of nanomaterials

2021 ◽  
Vol 10 (1) ◽  
pp. 370-384
Author(s):  
Tao Meng ◽  
Kanjun Ying ◽  
Xiufen Yang ◽  
Yongpeng Hong
Keyword(s):  
Mechanical Properties ◽  
Cement Paste ◽  
Cement Hydration ◽  
Inhibitory Effect ◽  
Test Methods ◽  
Cement Clinker ◽  
Hydration Products ◽  
Nucleation Effect ◽  
Nano Graphene ◽  
Nano Titanium Dioxide

Abstract Filling and nucleation are the mechanisms of modifying cement paste with nanomaterials, as investigated by previous studies, and are difficult to reflect the different effects of nanomaterials, especially on the changes of cement clinker and hydration products in the cement hydration process. In this study, the mechanisms of modifying cement paste with nano-calcium carbonate (NC), nano-graphene oxide (NG), nano-silica (NS), and nano-titanium dioxide (NT) were investigated by determining the mechanical properties of cement paste treated with nanomaterials and analysing the changes in the cement clinker (tricalcium silicate and dicalcium silicate), hydration products (portlandite and ettringite), and microstructure through many micro-test methods. The results indicate that the incorporation of nanomaterials could improve the early strength of cement paste specimens due to more consumption of cement clinker. Meanwhile, different nanomaterials promote the formation of different hydration products at early ages. C–A–S–H gel, flower-like ettringite, and C–S–H seeds are widely distributed in the cement paste with the incorporation of NC, NG, and NS, respectively. NT exhibits insignificant nucleation effect and has inhibitory effect on portlandite precipitation. This study provides key insights into the mechanism of nanomaterials from the perspective of cement hydration, which may promote the further research and application of nanomaterials in the cement and concrete industries.

scholarly journals Alkali-Activated Slag/ Fly Ash Concrete: Mechanism, Properties, Hydration Product and Curing Temperature

2020 ◽  
Vol 9 (9) ◽  
pp. 204-215
Keyword(s):  
Fly Ash ◽  
Hydration Product ◽  
Test Methods ◽  
Curing Temperature ◽  
Environmental Friendliness ◽  
Alkali Activated Slag ◽  
Fly Ash Concrete ◽  
Activated Slag ◽  
Alkali Activated Concrete ◽  
Alkali Activated

Alkali-activated concrete (AAC) is mounting as a feasible alternative to OPC assimilated to reduce greenhouse gas emanated during the production of OPC. Use of pozzolana results in gel over-strengthening and fabricate less quantity of Ca(OH)2 which provide confrontation to concrete against hostile environment. (AAC) is potential due to inheriting the property of disbursing CO2 instantly from the composition. Contrastingly an option to ordinary Portland cement (OPC), keeping this fact in mind the goal to evacuate CO2 emits and beneficiate industrial by-products into building material have been taken into consideration. Production of alkali-activated cement emanates CO2 nearly 50-80% less than OPC. This paper is the general assessment of current report on the fresh and hardened properties of alkali-activated fly ash (AAF), alkali-activated slag (AAS), and alkali activated slag and fly ash (AASF) concrete. In the recent epoch, there has been a progression to blend slag with fly ash to fabricate ambient cured alkali-activated concrete. Along with that the factors like environmental friendliness, advanced studies and investigation are also mandatorily required on the alkali activated slag and fly ash concrete. In this way, the slag to fly ash proportion impacts the essential properties and practical design of AAC. This discusses and reports the issue in an intensive manner in the following sections. This will entail providing a good considerate of the following virtues like workability, compressive strength, tensile strength, durability issues, ambient and elevated-temperature curing of AAC which will improve further investigation to elaborate the correct test methods and to commercialize it.

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

scholarly journals Synthesis of Titanium Containing SBA-15 and Its Application for Photocatalytic Degradation of Phenol

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Lili Yang ◽  
Zeyu Jiang ◽  
Sufeng Lai ◽  
Chongwen Jiang ◽  
Hong Zhong
Keyword(s):  
Waste Water ◽  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Physicochemical Properties ◽  
Phenol Degradation ◽  
Titanium Content ◽  
Structure Change ◽  
Cyclic Performance ◽  
One Pot ◽  
Simulated Waste

We synthesized Ti-containing SBA-15 by one-pot hydrothermal method and extensively investigated its physicochemical properties and examined its photocatalytic activity to degrade phenol. It’s shown that appropriate amount of titanium could be effectively incorporated into the framework of SBA-15 without provoking structure change and the tetrahedrally coordinated titanium species were well-ordered in Ti-incorporated SBA-15. Under UV-irradiation, the Ti-containing SBA-15 exhibits good photocatalytic activity for phenol degradation in the simulated waste water. The higher photocatalytic activity of Ti-containing SBA-15 to degrade phenol was ascribed to the more titanium content and anatase titanium dioxide. In addition, the new photocatalyst displays a good regeneration and cyclic performance after six runs.

Study on the Calcinations of Recycled Cement Clinker Using Waste Concrete and Waste Clay Brick

2014 ◽  
Vol 629-630 ◽  
pp. 337-342
Author(s):  
Hong Mei Ai ◽  
Su Feng Zhu
Keyword(s):  
Hydration Product ◽  
Raw Material ◽  
Cement Clinker ◽  
Sintering Process ◽  
Clay Brick ◽  
Cement Production ◽  
Construction Waste ◽  
Industry Waste ◽  
Waste Concrete ◽  
Hydration Characteristics

Utilizing construction waste, mainly waste concrete, to produce recycled cement, provides possibility for realizing the closed circulation between concrete and cement, which is an effective way for sustainable development of cement and concrete industry. Waste clay brick (WCB) and its surface-coated waste mortar are inevitably introduced into the raw meals while waste concrete is used in cement production. So on the basis of the composition characteristics of construction waste, considering of optimizing the performance of recycled cement and improving the adaptability of recycled cement to complex raw material, it's necessary to study the effect of raw meal mixing waste concrete and WCB on sintering process and property of recycled cement clinker. Mixing waste concrete and WCB in three different proportions, the burnability of raw meal, clinker mineral composition, clinker mineral morphology and hydration characteristics of recycled cement have been studied in this paper. The results indicate, the presence of WCB is beneficial for the generation and development of silicate minerals; with increasing proportion of WCB, the content of f-CaO in recycled cement clinker rises, the structure of C-S-H gel from hydration product presents higher densification and the compression strength of 3d and 28d curing period are enhanced.

Xonotlite and Hillebrandite as Model Compounds for Calcium Silicate Hydrate Seeding in Cementitious Materials

2020 ◽  
pp. 036119812094320
Author(s):  
Elisabeth John ◽  
Christian Lehmann ◽  
Dietmar Stephan
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Model Compound ◽  
Hydration Product ◽  
Cementitious Materials ◽  
Nucleation Site ◽  
Hydration Products ◽  
Sem Images ◽  
Pit Formation ◽  
Nanoparticle Additives

The demand for more environmentally friendly cement with no disadvantages in relation to hydration activity has led to the development of various additives to accelerate cement hydration. As calcium silicate hydrate (C-S-H) is the major hydration product of cement and is responsible for its mechanical properties, it plays an outstanding role in the discussion of nanoparticle additives. Nevertheless, the investigation of its mechanism of action is complicated by the similarity of its properties to those of the C-S-H that forms as an initial hydration product. Crystalline C-S-H phases, on the other hand, can be easily distinguished from the original hydration products, which makes them a valuable model compound for studying the mechanisms of nucleation seeding in cementitious materials. In this paper, the effect of crystalline types of C-S-H as nucleation seeds are presented. Xonotlite and hillebrandite were thoroughly characterized using nuclear magnetic resonance, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR) and were then used as an admixture for alite pastes. Low-vacuum SEM images of the hydrated pastes revealed that xonotlite can significantly promote the visible etch pit formation on C3S clinker particles, which was not found to be true for hillebrandite. Whether the phases act as a nucleation site is assumed to be strongly dependent on the mineralogy: hillebrandite appeared to be heavily overgrown, but xonotlite did not show any hydration products on its surfaces after the same hydration time of up to 24 h. The diverse effect of the minerals was confirmed by the accelerating behavior in isothermal heat flow calorimetry and by XRD.

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