• Cement
• /
• s.180
• /
• pp.27-35
• /
• 2008

• Cement Symposium
• /
• s.39
• /
• pp.184-191
• /
• 2012

• Cement Symposium
• /
• s.48
• /
• pp.10-17
• /
• 2021

• Cement Symposium
• /
• s.49
• /
• pp.69-74
• /
• 2022

• The Journal of Korean Academy of Prosthodontics
• /
• v.37 no.5
• /
• pp.651-657
• /
• 1999

This study was performed to investigate the retrievability of the cementation type implant abutments. The cements used in this study were Cavitec, Tembond and Zinc Phosphate Cement. The types of surface conditioning were no treatment, 50 microne sandblasting, 250 microne sandblasting, fine diamond finishing point and coarse diamond point. The retention of cast crown was measured with Instron Universal Testing Machine(Instron Engineering Co., U.S.A.). The results were as fellows: 1. The Maximium retention was obtained by the group of Z.P.C. cementation and Coarse diamond point surface conditioning. 2. Z.P.C. shows maximum retention, and reduced in orders Tembond, Cavitec, No cement. 3. The value of retention of surface condition was highest in coarse diamond point, lowest in no tretment. 4. The similar results were obtained between fine diamond point and 50 microne sandblasting, coarse diamond point and 250 microne sandblasting. 5. The were no direct corelation between mechanical retention and cementation retention.

• Journal of the Korean Ceramic Society
• /
• v.44 no.11
• /
• pp.633-638
• /
• 2007

The setting time of alkali activated slag cement tends to be much faster than ordinary Portland cement, and its compressive strength had been higher from the 1 day but became lower than that of the cement on the 28 days. According to the results of the surface observation, weight loss, compressed strength, and erosion depth tests on the sulphuric acid solution. It has been drawn that alkali activated slag cement has a higher sulphate resistance than ordinary Portland cement, and in particular, the alkali activated slag cement added 5 wt% alumina cement has little deterioration on the sulphuric acid solution. The reason why the alkali activated slag cement has higher sulphate resistance than other hardened cement pastes is that it has no $Ca(OH)_2$ reactive to sulphate ion, and there is little $CaSO_4{\cdot}2H_2O$ production causing volume expansion, unlike other pastes. And it is supposed that $Al(OH)_3$ hydrates with high sulphate resistance, which is produced by adding the alumina cement increases the sulfate resistance.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.16 no.3
• /
• pp.3533-3538
• /
• 1974

This study was attempted in order to search for physical properties of sail cement. In this study, soil samples were specified according to soil particle analysis and used for compaction, strength, abrasion, absorption tests respectively according to different cement contents. Cement content sused in each treatment were 6%, 8%, 10% and 12% of total weight of soil-consent mixture. In the test, compressise strengths of the specimens were measured at the following ages; 3 days, 7-days, 14-days, 21-days and 28-days. Abrasion and absorption tests of the specimens were carried out at the 7-days age only. The results obtained from the tests are summarized as follows; 1. As the cement contents were in creased, the compressive strengths of soil-cement were almost proportionally increased. 2. The Compressive strength of soil-cement was not always proporportional to ages. The gradient of compressive strength of the soil-cement was steeper as the cement content was rucreased. 3. As the cement content was increased, the amount of the weight loss of the samples due to the abrasion was decreased remarkably, giving no abrasion for about 8% of the cement content. 4. As the cement content was increased, the absorption ratio of the specimens was not changed remarkably.

• International Journal of Concrete Structures and Materials
• /
• v.7 no.2
• /
• pp.119-125
• /
• 2013

Carbonation is a natural ageing process for cement. This study focuses on how the carbonation rate varies with selected hydration times and atmospheric conditions during the early stages of reacting dried cement paste. Diffuse reflection Fourier transform infrared spectroscopy is shown to be a suitable technique to monitor the formation of carbonates in cement. Combined with a previously developed freeze drying technique, carbonation can be studied at specific hydration stages. In ambient air both calcium hydroxide and calcium silicate hydrate (C-S-H) in cement are carbonated. Increased hydration time enhances the carbon dioxide uptake, which indicates that the calcium in the hydration products reacts more easily than the calcium in the clinker phase. In a humid $CO_2$ atmosphere, the carbonation process is so pronounced that it decomposes C-S-H into calcium carbonate and silica. In a moist $N_2$ atmosphere no carbonation occurs, but the sulfate chemistry of the cement seems to be affected due to the formation of ettringite.

• Restorative Dentistry and Endodontics
• /
• v.20 no.1
• /
• pp.173-182
• /
• 1995

The purpose of this study was to evaluate the adaptability of light-cured glass ionomer cement to cavity walls. Class V cavities were prepared on the labial surfaces of extracted bovine incisor teeth. The cavities were restored with Fuji II as self-cured glass ionomer cement and Fuji II LC, Vitremer as light-cured glass ionomer cement. Fluorescent markers (fluoreceine and rhodamin B) were incorperated into liquid and primer for a better image of microscopic observation. Restored teeth were sectioned by longitudinal and labiolingual direction. The adaptability at the tooth-restoration interface was assessed incisally, axially and cervically by confocal scanning laser microscope. Following results were obtained : 1. Chemical-cured glass iomomer cement restoration showed close adaptation on the all of the cavity walls, but, cracks formed within the cement. 2. Light-cured glass ionomer cement restoration was well adapted to the cavity walls, but showed crack in the cement adjacent to axial dentinal wall. 3. There' was no significant difference in adaptability between two light-cured glass ionomer cement restorations.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.11a
• /
• pp.102-103
• /
• 2020

In this study, the effect of the change in the cement contents on the basic properties of the concrete and the estimation of the cement contents of hardened concretes using the hydrochloric acid melting heat. As a result of the study, as the cement contents increased, the fluidity and compressive strength increased, and there was no significant difference in the air contents and the unit volume mass. In addition, it showed a high correlation when compared with the estimated cement contents derived using the hydrochloric acid melting and the cement contents at the time of mixing. Therefore, it is considered that the hydrochloric acid melting is possible as a method of estimating the cement contents of concrete.