scholarly journals Mineral reactions in a model mantle: prediction of mineral compositions and assemblages

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The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.


2019 ◽  
Vol 770 (5) ◽  
pp. 51-56
Author(s):  
Yu.G. BORISENKO ◽  
◽  
R.M. AZAN ◽  
D.P. SHVACHEV ◽  
D.A. VOROBIEV ◽  
...  

2021 ◽  
Vol 13 (12) ◽  
pp. 6536
Author(s):  
Yanrong Zhao ◽  
Pengliang Sun ◽  
Ping Chen ◽  
Xiaomin Guan ◽  
Yuanhao Wang ◽  
...  

In this paper, a new method of basic oxygen furnace (BOF) slag component modification with a regulator was studied. The main mineral was designed as C4AF, C2S and C3S in modified BOF slag, and the batching method, mineral compositions, hydration rate, activation index and capability of resisting sulfate corrode also were studied. XRD, BEI and EDS were used to characterize the mineral formation, and SEM was used to study the morphology of hydration products. The results show that most inert phase in BOF slag can be converted into active minerals of C4AF and C2S through reasonable batching calculation and the amount of regulating agent. The formation of C4AF and C2S in modified BOF slag is better, and a small amount of MgO is embedded in the white intermediate phase, but C3S is not detected. With the increase in the CaO/SiO2 ratio in raw materials, the CaO/SiO2 ratio of calcium silicate minerals in modified BOF slag increases, the contents of f-CaO are less than 1.0%, and the activity index improves. Compared with the BOF slag, the activity index and exothermic rate of modified BOF slag improved obviously, and the activity index of 90 days is close to 100%. With the increase in modified BOF slag B cement, the flexural strength decrease; however, the capability of resisting sulfate corrode is improved due to the constant formation of a short rod-like shape ettringite in Na2SO4 solution and the improvement of the structure densification of the hydration products.


2021 ◽  
pp. 108201322199125
Author(s):  
Margaret A Olorunfemi ◽  
Olugbenga O Awolu ◽  
Victor N Enujiugha

Gluten-free flours that are nutritionally balanced with appropriate functional characteristics were developed by supplementation of native and modified acha flours with protein, dietary fiber and antioxidants-rich mango kernel and soy cakes flours. Acha flour was subjected to chemical and enzymatic modifications. The proximate, mineral compositions, bioactive and antinutrients properties of the composite flours were evaluated. The water content of the composite flours with native and chemically modified acha flour was between 7.62 and 9.30%, while that of enzymatic acha flour was between 10.12 and 10.79%. However, samples made with 20 and 30% incorporated mango kernel flour had around 13 and 19% increase in the protein content respectively, others including sample with enzymatically modified acha flour had lower protein content. On the other hand, all samples with enzymatically modified acha flour had between 83 and 100% increase in fibre content. The Na/K ratio of all the samples were less than one, as nutritionally required. Samples with enzymatically modified acha flour had best total flavonoid (0.03–0.77 mgGAE/g), total phenol (2.35–11.99 mgTAE/g) and DPPH radical scavenging activities (58.29–94.02%) contents. In addition, samples with enzymatically modified acha flour had the least antinutritional values. Although all the samples had values that were significantly (p ≥ 0.05) different, the samples had significant protein, dietary fiber, minerals and antioxidants contents, while the antinutritional contents were well lower than the standard.


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