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XRD pattern of C3S + C3A mixture after 3 hours of hydration: A-alite, B-belite, C-tricalcium aluminate, P-portlandite, W-C3A·CaCO3·11H2O.
Source publication
The paper presents the results of investigation over influence of 0.3% addition of hydroxypropyl methylcellulose (MC) of 40 and 70 Pa·s viscosity on the hydration process of main clinker phases: C3S and C3A and also their mixture, both in presence and absence of gypsum.During the research it has been indicated that methylcellulose inhibits the hydr...
Contexts in source publication
Context 1
... and tricalcium aluminate were the dominating phases after three hours from the start of the process, while the intensity of portlandite characteristic peak was low ( fig. 2). Contrary, the peak intensity of portlandite was significant after three hours of hydration of alite alone [2]. The hydration process of alite and tricalcium aluminate progresses with time. After 168 hours of hydration high intensity peaks of portlandite appear next to the peaks of alite and C 3 A ( fig. 3). ...
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Citations
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Ceramic tiles and ceramic tile adhesives (CTA) are two impressive materials that have changed construction history. Ceramic tiles could not provide their beauty and durability for buildings when used as a covering both for the inside and exterior finishing without CTA. Nowadays, they are complex multi-component systems. Among the various CTAs, cementitious products are the most commonly used. This article presents an extensive review of the literature, showing how they are perceived in the scientific literature today. In this paper, an attempt is made to review individual adhesives’ ingredients’ effects on their properties, with particular reference to redispersible polymer powders and methylcellulose ethers. The article presents the basics of the CTAs, assessing and verifying the constancy of their performance in force in European Union countries. Furthermore, it gives a critical review of CTA’s normalized measurement methodologies. The study also draws attention to the need to consider measurement uncertainty in decision-making and conformity assessment, supported by an analysis of the results of multi-annual inter-laboratory studies and market surveillance tests. Future research suggestions are also made based on the review, mainly from the adhesive manufacturer’s perspective.
This study compares the performance of light-emitting cement and polymeric mortars. To accomplish this objective, cement, polyester, and epoxy mortars were prepared with and without strontium aluminate (SrAl2O4: Eu2+ Dy3+) based light-emitting phosphor (LEP). The water absorption, compressive strength, ultrasonic pulse velocity, and luminescence intensity tests were performed to compare and assess the characteristics of LEP-based cement and polymeric mortars. The results show that using strontium aluminate phosphor improved the mechanical performance of cement and polymer-based mortars. Notably, polymeric mortars demonstrate significantly lower water absorption compared to their cement counterparts. Furthermore, afterglow performance investigation confirmed that light-emitting polymeric mortars exhibit more persistent luminosity than cement counterparts. Analytical characterizations employing X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy elucidated the effective role of light-emitting phosphors within cement and polymeric matrices. Based on the test results, it is deduced that employing strontium aluminate-based light-emitting phosphor in producing light-emitting polymeric composites could be a promising strategy for sustainable and resilient building design.
This study investigated the microstructure of ordinary Portland cement paste subject to early age ambient pressure carbonation curing in a flexible enclosure. The high-pressure carbonation at 5 bar and the normal hydration were used as references. Both ambient-pressure and high-pressure carbonation was carried out with pure gas (99.9% CO2) for 12 h. It was found that ambient pressure carbonation could achieve comparable carbon uptake and strength gain as high pressure at both early and late age. Nevertheless, ambient carbonation was more economic and practical for precast products of different sizes and shapes. In order to examine this mechanism, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), ²⁹Si nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and nitrogen adsorption/desorption (NAD) were adopted to characterize the microstructural development after early carbonation curing under both ambient pressure and high pressure. Ambient pressure carbonation reaction took place more on the surface than in the core due to the limited CO2 diffusion so that the surface layer was more densified. The NAD results showed that ambient pressure performed better than high pressure in terms of reducing the cumulative pore volume and refining the capillary pore size. Ambient pressure could produce well crystalline carbonates as high pressure as deduced by XRD, TGA, FTIR and SEM images. The generation of calcium carbonate and its intermingling effect with hydration products were the main reasons for the strength gain and microstructural development of paste after early carbonation. Besides, SEM images showed that ambient pressure tended to produce calcium carbonates along the surface of C-S-H filling pore structure. As subsequent hydration proceeded, the increase of well crystalline carbonates was seen more in ambient pressure carbonation than high pressure based on TGA. NMR revealed that ambient pressure could enhance the polymerization of silicon in C-S-H promoting the early strength gain and maintain high Ca/Si ratio.
This work has presented an analysis of the consolidation process of dry set mortars, using the oscillatory rheometry technique as a method of approach. The method was applied to a set of mortar mixtures, whose proportions between its components were varied within limits stipulated by the author by means of an experimental planning, following the Central Composite Rotational Design (CCRD) methodology, in which the proportions between the dry set mortars components represented the independent factors. The samples were subjected to a shear strain controlled by the device, while both the resulting shear stress (τ) and the phase angle (δ) were measured. The strain was applied to the sample in a 1Hz frequency, resulting in one extraction per minute over 200 minutes. In the proposed approach the compactness properties of mixtures were evaluated as dependent factors, from the Wet Packing Method (WPM), as also were the fundamental rheological properties, interpreted from the oscillatory rheometry, and their derived factors, calculated from the former ones. This work aimed to comprehend the consolidation process as an inherent phenomenon of dry set mortar, as well as to relate their kinetics to the parameters assumed as independent factors. The analyzing methodology involved qualitative and quantitative evaluations of the rheological quantities over the performed tests, in addition to a statistical analysis which related the τ and δ values to the independent factors. The results showed that the consolidation process of dry set mortars is a continuous phenomenon that occurs at least since the first 30 minutes after the mixture. It was also evidenced that the chosen fundamental rheological properties can describe the phenomenon from their measurement via oscillatory rheometry. The independent factors presented, at different levels, influence on the observed consolidation phenomenon. It was observed that the contents of moisture and sand tend to delay the process as a whole and that the polymers contents used (EVA and HEC) have the opposite effect. It was possible to notice a relationship between the granular mixtures compactness and the consolidation process, as the mixtures with compacter granular structure tend to delay the consolidation process more than mixtures with lower compactness levels, due to their bigger content of excess water.
