• Geomechanics and Engineering
• /
• v.18 no.4
• /
• pp.427-437
• /
• 2019

Waste materials are being produced in huge quantities globally, and the usual practice is to dump them into legal or illegal landfills. Recycled tiles (RT) are being used in soil stabilisation which is considered as sustainable solution to reduce the amount of waste and solve the geotechnical problems. Although the stabilisation of soil using RT improved the soil properties, it could not achieve the standard values required for construction. Thus, this study uses 20% RT together with low cement content (2%) to stabilise soft soil. Series of consolidated undrained triaxial compression tests were conducted on untreated and RT-cement treated samples. Each test was performed at 7, 14, and 28 days curing period and 50, 100, and 200 kPa confining pressures. The results revealed an improvement in the undrained shear strength parameters (cohesion and internal frication angle) of treated specimens compared to the untreated ones. The cohesion and friction angle of the treated samples were increased with the increase in curing time and confining pressure. The peak deviator stress of treated samples increases with the increment of either the effective confining pressures or the curing period. Microstructural and chemical tests were performed on both untreated and RT-cement treated samples, which included field emission scanning electron microscopic (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX). The results indicated the formation of cementation compounds such as calcium aluminium hydrate (C-A-H) within the treated samples. Consequently, the newly formed compounds were responsible for the improvement observed in the results of the triaxial tests. This research promotes the utilisation of RT to reduce the amount of cement used in soil stabilisation for cleaner planet and sustainable environment.

• Cement Symposium
• /
• no.1
• /
• pp.23-30
• /
• 1973

In this paper, the reaction of the formation of portland cement clinker is reviewed. 1. When the specimen is heat-treated, the glassy phase melt with increasing temperature, and the starting materials are dissolved into the melt. After the melt is saturat

• Journal of Microbiology and Biotechnology
• /
• v.22 no.11
• /
• pp.1568-1574
• /
• 2012

Microbiological calcium carbonate precipitation (MCCP) has been investigated for its ability to improve the durability of cement mortar. However, very few strains have been applied to crack remediation and strengthening of cementitious materials. In this study, we report the biodeposition of Bacillus subtilis 168 and its ability to enhance the durability of cement material. B. subtilis 168 was applied to the surface of cement specimens. The results showed a new layer of deposited organic-inorganic composites on the surface of the cement paste. In addition, the water permeability of the cement paste treated with B. subtilis 168 was lower than that of non-treated specimens. Furthermore, artificial cracks in the cement paste were completely remediated by the biodeposition of B. subtilis 168. The compressive strength of cement mortar treated with B. subtilis 168 increased by about 19.5% when compared with samples completed with only B4 medium. Taken together, these findings suggest that the biodeposition of B. subtilis 168 could be used as a sealing and coating agent to improve the strength and water resistance of concrete. This is the first paper to report the application of Bacillus subtilis 168 for its ability to improve the durability of cement mortar through calcium carbonate precipitation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2002.10a
• /
• pp.345-348
• /
• 2002

The dredged soils of rural streams can be treated with cement for recycling. It is very important to know whether the treated soils have achieved some required qualities for further treatments if the soils are mixed with cement. In this study, fall-cone test was used to examine changes in workability and compactibility during an curing time of soil-cement mixture. Test results showed that fall-cone apparatus can be satisfactorily used for this purpose. Although there was some difference of initial curing time and cement contents, the engineering properties of treated soils were little affected.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.3
• /
• pp.379-386
• /
• 2003

Statement of problem. Resin cements are widely used in adhesive dentistry specially on all ceramic restorations. It is needed to find out adequate bonding strength between different porcelain surface treatments, commercially available porcelains, and different resin cement systems. Purpose. The purpose of this study was to evaluate shear bond strength of resin cements bonded to porcelains in three different modalities; 5 different porcelain surface treatments, 3 different resin cement systems and 3 different commercially available pressable porcelains. Material and Method. This study consisted of 3 parts. Part I examined the effect of five different surface treatments on the pressable porcelain. Fifty discs (5 mm in diameter and 3 mm in height) of Authentic porcelain were randomly divided into 5 groups (n = 10). The specimens were sanded with 320 grit SiC paper followed by 600 grit SiC paper. The specimens were treated as follow: Group 1-Sandblasting (aluminum oxide) only, Group 2 - sandblasting/ silane, Group 3 - sandblasting/ acid etching/ silane, Group 4 - acid etching only, Group 5 - acid etching/ silane. Part II examined the shear bond strength of 3 different resin cement systems (Duolink, Variolink II, Rely X ARC) on acid etching/ silane treated Authentic pressable porcelain. Part 3 examined the shear bond strength of Duolink resin cement on 3 different pressable porcelains (Authentic, Empress I, Finesse). All cemented specimens were stored in distilled water for 2 hours and tested with Ultradent shear bond strength test jig under Universal Instron machine until fracture. An analysis of variance(ANOVA) test was used to evaluate differences in shear bond strength. Result. The shear bond strength test resulted in the following: (1) Acid etched porcelains recorded greater shear bond strength values to the sandblasted porcelains. (2) Silane treated porcelains recorded greater shear bond strength values to non-silane treated porcelains. (3) There was no significant difference between sandblasting/ acid etching/ silane treated and acid etching/ silane treated porcelains. However those values were much higher than other three groups. (4) The shear bond strength with Variolink II was lower than the value of Duolink or Rely X ARC. (5) The shear bond strength of Finesse was lower than the value of Authentic or Empress I.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.123-126
• /
• 1999

On this study, CaCO3(CF) treated with H2SiF6 as a fluorine copmpound and analyzed its basic property. When CF added with cement and mortar, we also examined effect of CF on the physical property of cement and mortar.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.43 no.3
• /
• pp.77-84
• /
• 2001

A few study has been performed on the durability of subbase treated with geo-cement for the farm road although many papers for the road treated with soil-cement were published. The objectives of the study are to develop the stabilizing method of subbase using additives of cement groups and 2nd additives such as gypsum and MgO, etc. A series of test was performed to investigate possible mixing ratios with geo-cement A, B, C, D and 2nd additives on the various soft soils from the rice paddy. Based on test results, durability index was greatly affected by geo-cement D which was mainly composed with gypsum. Compressive strength of clayey soil such as Soil I was less than threshold strength(30kgf/$\textrm{cm}^2$) but the strength was increased as addition of gypsum and MgO. It is recommended that geo-cement for soil stabilization has to be carefully chosen because strength characteristics of subbase are varied not only with soils but also with addition of geo-cement and 2nd additives. The developed method in this study can be used subbase treatment of low-cost agricultural roads.

• Structural Engineering and Mechanics
• /
• v.89 no.4
• /
• pp.349-362
• /
• 2024

High-performance fiber-reinforced cement composites (HPFRCC) are new materials created and used to repair, strengthen, and improve the performance of different structural parts. When exposed to tensile tension, these materials show acceptable strain-hardening. All of the countries of the globe currently seem to have a need for these building materials. This study aims to create a low-carbon HPFRCC (high ductility) that is made from materials that are readily available locally which has the right mechanical qualities, especially an increase in tensile strain capacity and environmental compatibility. In order to do this, the effects of fiber volume percent (0%, 0.5%, 1%, and 2%), and determining the appropriate level, filler type (limestone powder and silica sand), cement type (ordinary Portland cement, and limestone calcined clay cement or LC3), matrix hardness, and fiber type (ordinary and oxygen plasma treated polypropylene fiber) were explored. Fibers were subjected to oxygen plasma treatment at several powers and periods (50 W and 200 W, 30, 120, and 300 seconds). The influence of the above listed factors on the samples' three-point bending and direct tensile strength test results has been examined. The results showed that replacing ordinary Portland cement (OPC) with limestone calcined clay cement (LC3) in mixtures reduces the compressive strength, and increases the tensile strain capacity of the samples. Furthermore, using oxygen plasma treatment method (power 200 W and time 300 seconds) enhances the bonding of fibers with the matrix surface; thus, the tensile strain capacity of samples increased on average up to 70%.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.1195-1203
• /
• 2006

Water that is treated by passing through a magnetic field of certain strength is called Magnetic Field Treated Water(MFTW). Previous research indicate that use of MFTW can save 5% of cement dosage, decrease bleeding of concrete, and improve resistance to freezing. The reason why MFTW can improve characteristics of concrete can be explained by the molecular structure of water. Magnetic force can break apart water clusters into single molecules or smaller ones, therefore, the activity of water is improved. While hydration of cement particles is in progress, the MFTW can penetrate the core region of cement particles more easily. Hence, hydration takes place more efficiently which in turn improves concrete compressive strength. Test results demonstrate that the compressive strength of the sodium silicate cement grout homogel increases by approximately 20 - 50% by using the MFTW.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.2
• /
• pp.285-291
• /
• 1998

The purpose of this study was to asses the shear bond strengths of 3 types of glass ionomer cement and 1 type of composite resin to dentinal surface with or without ZOE pretreatment. 80 extracted tooth specimens are divided into two groups; the control group (40 specimens) is not treated with ZOE and the other(40 specimens) is ZOE pretreated during 24 hours before bonding procedure. Shear bond strengths were measured with universal testing machine (Instron, Model 4301) and statistically processed by ANOVA and t-test. The results were as follows: 1. Bond strength of the ZOE treated experimental group showed lower than the control group, except chemical cured glass ionomer cement(p<0.05). 2. After ZOE surface treatment, the bond strength of composite resin was superior than glass ionomer cement and all experimental group was decreased (p<0.05). 3. It has nothing to do with ZOE surface treatment, that chemical curing glass ionomer cement was showed lowest bond strength.