• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.593-600
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• 2014

Normal rice starch (NRS) possesses high gelling and retrogradation tendencies, with poor freeze-thaw stability. This study investigated the effects of partial replacement of waxy rice starch (WRS) with gums on the pasting and viscoelastic properties as well as the freeze-thaw stability of the WRS paste. Xanthan gum (XAT), locust bean gum (LBG), and their mixtures were individually mixed with WRS at a ratio of 1:19 (w/w). WRS-gum mixtures were pasted using a rapid visco-analyzer at 5% total solid content, and analyzed with respect to the pasting and viscoelastic characteristics, and freeze-thaw stability. Pasting properties of WRS were retarded in pasting temperature and enhanced in pasting viscosity (although peak viscosity was varied) by partial replacement with gum and gum mixtures. Storage moduli of WRS-XAT:LBG pastes became similar to those of NRS paste with increasing angular frequency from 1 to 10 rad/s. Finally, WRS-XAT and WRS-XAT:LBG possessed more enhanced freeze-thaw stability than NRS.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.71-77
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• 2010

Anti-freezing layer does not used in case of non frost heaving in subgrade soils. In this case, the modulus of subgrade soils were varied with freezing and thaw cycles under non frost heaving. That effect should be properly considered in pavement design. Impact resonance test that is nondestructive testing method was used for continuously determining the modulus of subgrade soils during freezing and thaw cycle. The modulus of subgrade soils was identical with freezing and thaw cycles under closed freezing and thaw system which is no water supplement into specimen during testing. There was also no difference in the modulus of subgrade soil between before and after freezing-thaw cycles for all specimens with different water content and density. That is thaw-weakening of subgrade soils do not occur under closed freezing and thaw system. The moduli at freezing conditions are varied with water content and density, but it can be ignored in practical design sense.

• Journal of the Korea Institute of Building Construction
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• v.7 no.3
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• pp.107-113
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• 2007

This study is to investigate adhesive properties depending on the temperature, humidity, and freeze-thraw of the Steel plate adhesive strengthening method by the epoxy resin. The results are summarized as following. For the temperature variation, the debonding failure appear only after 1 cycle of temperature varoation because the coefficient of thermal expansion of the epoxy resin is comparatively large, and the bonding strength is decreased. The deformation properties and ultrasonic pulse velocity on each materials are similar until 4 cycles on the dry and moisture test. As the freeze-thraw test, the epoxy resin is degraded easily subjected to freeze-thaw cycle, comparatively easy, so the debonding failure may occur in short term because of the freeze-thaw repeatition.p

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.26-32
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• 2012

Recently, concrete using multicomponent blended cement has been required to increase the freeze-thaw and sulfate resistances of concrete structures exposed to a marine environment. Thus, the purpose of this study was to propose the use of concrete containing multicomponent blended cement as one of the alternatives for concrete structures exposed to a marine environment. For this purpose, batches of concrete containing ordinary portland cement (OPC), binary blended cement (OPC-G, G: ground granulated blast slag), ternary blended cement (OPC-GF, F: fly ash), and quaternary blended cement (OPC-GFM, M: mata-kaolin) were made using a water-binder ratio of 50%. Then, the durability levels, including thesulfate and freeze-thaw resistances, were estimated for concrete samples containing OPC, OPC-G, OPC-GF, and OPC-GFM. It was observed from the tests that the durability levels of the concrete samples containing OPC-G and OPC-GF were found to be much better than that of the concrete containing OPC. The optimum mixing proportions were a40% replacement ratio of ground granulated blast slag for the binary blended cement and a30% replacement ratio of ground granulated blast slag and 10% fly ash for the ternary blended cement.

• Journal of the Korean GEO-environmental Society
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• v.7 no.1
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• pp.29-39
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• 2006

Recently, Korea brings to remarkable levels about industrialization, modernization, population and development of technology. Especially, the rapidly growing from this technology has increased the burden on existing industrial waste landfills. The purpose of this research is to existing knowledge base of landfill cover liner behavior during periods freeze/thaw. Although these tests have been invaluable in clarifying the problem of freeze/thaw, extending the results of such experimental studies to prototype landfills are questionable. For this investigation, the author utilized a large scale laboratory simulation allowing inclusion of the field depth of the cover systems, layered soil profiles, rainfall simulation, a cold climate and boundary conditions similar to those encountered in the landfill. And the soil materials used stabilized soils (mixed clays, cements, and minerals) instead of clays. The bottom liners are made up of drainage layer (30cm), stabilized layer (75cm), and leach collection layer (60cm). The stabilized layers are made up of supporting layer (45cm) and impermeable layer (30cm) - consisted of $P_A$ and $P_B$ layer.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.1
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• pp.4599-4613
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• 1978

This study was intended to investigate the effects of bituminous material content of soil-cement mixtures on their durability. For the purpose, unconfined compressive strength test, Freeze-thaw test, and wet-dry test were performed with three types of soil. Each type of soil was mixed with three levels of cement content and each soil-cement mixture was mixed with four levels of bituminous material content. For the unconfined compressive strength test, Freeze-thaw test and wet-dry test, 324, 108, and 108-specimens were prepared respectively. Unconfined compressive strength was measured at age of 7-days, 14-days and 28-days using 108-specimens in each age. The soil-cement loss rate due to freeze-thaw and wet-dry were calculated after 12 cycles of test using 108-specimens in each test. The results are summarized as follows : 1. Optimum moisture content was increased with increase of cement content, but maximum dry density was changed irregulary with increase of the cement content. 2. The unconfined compressive strength was increased with increase of cement content, bituminous material content and curing age. Cement is more effective factor than bituminous material on unconfined compressive strength of soil-cement Mixture. 3. It is estimated as the most economical cement content that the recommended cement content of A.S.T.M. because increasing rate of unconfined compressive strength at age of 28-days was low when cement content is above the recommanded cement content of A.S.T.M. among all types of soil. 4. Although a portion of cement content is substituted for bituminous material, the necessary unconfined compressive strength can be obtained. 5. The soil-cement loss was more influenced by wet-dry than Freeze-thaw 6. The bituminous material is more effective on the decrease of soil-cement loss than increase of unconfined compressive strength 7. The void ratio of soil-cement mixture was changet irregularly with increase of cement content, but that was decreased in proportion to the increase of bituminous material content. 8. The regression equation between the unconfined compressive strength and soil-cement loss rate were obtained as table 7.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.145-150
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• 2011

Variations of physical properties such as weight loss rate, wave velocity and uniaxial compressive strength after performing freeze-thaw cyclic test were measured in order to define weathering characteristics of sandstone and andesite. Weight change in specimens of the two rocks decreased with increasing the repetition number of freeze-thaw cyclic test. In particular, weight loss of andesite specimens was very irregular. P-wave velocity of sandstone specimens decreased more than 5%. On the other hand, P-wave velocity of andesite specimens do not vary up to 500 cycles and decreased more than 5% after 1000 cycles. This implies that the sandstone are easily weakened and loosened by weathering processes, while the andesite are relatively strong. In addition, the wave velocity changes of the andesite specimens coincident with the weight change. Uniaxial compressive strengths of the sandstone specimens slightly decreased at the early stage of the freezing-thawing cyclic test, then tended to be irregular after 64 cycles. In conclusion, the rock specimens showed smaller weight loss, less had lower strength reduction rate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.227-233
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• 2008

Porous concrete has large continuous voids of 20-30 % by volume, and this concrete is attractive as environmental material in Japan i.e. permeable road pavement, river bank protection with vegetation and green roof system which influence thermal environment. It is necessary to confirm the frost resistance when constructing porous concrete structure in cold region. However applicable test method and evaluation criterion of porous concrete has not defined yet. Therefore, the object of this study is to investigate the frost resistance of porous concrete and this investigation attempts to address this concern by comparing 4 kinds of specified freezing and thawing tests methods (JIS A1148 procedure A/B and RILEM CIF/CDF test) in consideration of actual environment. RILEM freeze-thaw tests are different from JIS A1148 freeze-thaw tests, which are widely adopted for evaluating the frost resistance of conventional concrete in Japan, in water absorption, cooling rate, length of freezing and thawing period, and number of freezing and thawing cycles. RILEM CIF test measures internal damage and is primarily applicable for pure frost attack. CDF test is appropriate for freeze-thaw and de-icing salt attack. JIS A1148 procedure A/B showed extremely low frost resistance of porous concrete if the large continuous voids were filled with water and the ice expansion in the large continuous voids set in during cooling. Frost resistance of porous concrete was improved by mixing coarse aggregate (G7) which particle size is smaller and fine aggregate in JIS freezing and thawing tests. RILEM CIF/CDF test showed that freeze-thaw and de-icing resistance of porous concrete was seems to be superior in that of conventional concrete.

• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.387-394
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• 2008

The Physical property changes of calcined clay by carburization were investigated studied. The carburization mechanism is the penetration of carbon which occurred during incomplete fuel combustion into crevice of clay structure. The experiments for elasticity and freeze-thaw resistance were conducted, and the results can be summarized as follows: Dynamic modulus of elasticity and also freeze-thaw resistance of calcined clay by carburization treatment increased more than 92% after testing 300 cycle, which was more improved than 88% of calcined clay. Therefore, it can decrease the possibility of winter-sowing, which is one the weakness of calcined clay. It is on the basis of the fact that the porosity of calcined clay by carburization treatment is about 12%, which indicates smaller pore spaces comparing with the 14% of porosity of calcined clay and those values were calculated by apparent porosity show and also supported by SEM images. Infrared emissivity of calcined clay by carburization treatment and calcined clay were respectively 0.92 and 0.9l at $80^{\circ}C$. However, those values were 0.91 and 0.88 at $200^{\circ}C$, which means infrared emissivity of calcined clay by carburization treatment shows 3.6% higher than the calcined clay. Moreover, within the wavelength range from 3 to $7\;{\mu}m$, while the calcined clay had low infrared emissivity, the calcined clay by carburization treatment had increased infrared emissivity. It is inferred that it was affected by carbon element that has high infrared absorptivity within this wavelength range.

• Journal of the Korean Geosynthetics Society
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• v.8 no.1
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• pp.53-59
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• 2009

A new system of modified freeze-thaw testing apparatus is introduced. This system is developed to evaluate the geotechnical parameters and their dependence upon freezing-thawing history of frost-susceptibility soil. A necessary condition for stationary frost heaving is clarified in this paper. The method changes the thermal boundary condition up to the net heat flow at the freezing frost becomes zero. The effectiveness of this method is verified by freeze-thaw tests. Frost heaving observed after the application of the method is found to be due to another frost heaving action called long-term frost heaving. This frost heaving has already been studied and is considered ignorable as engineering factor because of its small heaving amount.