• 한국세라믹학회지
• /
• 제13권2호
• /
• pp.3-7
• /
• 1976

Influences of chlorides(CaCl2, MgCl2, NaCl) on the colouring effect of Fe component in white portland cement was investigated. Chlorides enhance the whiteness of the white portland cement owing to volatilization of Fe2O3 and translation of ferrite composition toward C2F. This translation is caused by consumption of alumina at the formation of C12A7, the formation of which is promoted in the presence of chloride. With decrease of p in ferrite composition C6F1-pAp, transfer of Fe3+ from 4 to 6 coordinated cite is occurred, and as a result, whiteness is raised. Hydration process of the cement containing a small amount of chloride differs little from the one without chloride.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
• /
• pp.66-71
• /
• 1998

Recently, it has been increased to construct massive concrete structures, like under-ground structure, offshore structure etc., ie. concrete construction have become larger and higher and are demanding lower heat concrete to prevent thermal cracking. It has been progressed to replace cements with fly-ash and slag to lower heat of hydration, but it is hard to control quality of the mineral admixtures in stage of adjusting of real construction. Application of low heat portland(Belite Rich) cement for the mass concrete is the best solution to satisfied those requirements. Here are explained the basic properties of fresh concrete as well as hardened concrete of using low heat portland cement(LHPC). Also, we compare the results of adiabatic temperature rise test using LHPC and OPC.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.297-302
• /
• 2001

SRC pier at KTE 6-1 construction area is a very important structure. Precise control of quality is needed. This pier has 3.50m$\times$3.73m section and 38.20m length. So this structure must be treated as mass concrete and thermal crack caused by hydration heat should be controled. In this project belite cement concrete is used to control the thermal crack. As a result of adapting belite cement concrete perfect control is achieved. Finally, hydration heat FEM analysis of horizontal element is executed for Ordinary Portland Cement concrete and belite cement concrete. In comparison of two results, it is confirmed that using low heat portland cement concrete is necessary.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.303-308
• /
• 2001

Recently, concrete structures have become larger and higher and are demanding high performance concrete with lower heat to prevent thermal cracking, far greater workability, high strength and durability, Application of low heat portland(Type IV) cement for the high performance concrete is the best solution to satisfied those requirements. Here are explained the effect on the properties of high flowing concrete using low heat portland cement by material and mixing variations. Variables for sensitivity test were selected items like finess modulus of aggregates, particle size of limestone powder, unit water, superplasticizer, viscosity agent and concrete temperature. The results of this study were be applied to slurry wall of #215 and #216 of underground LNG tank in Inchon.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
• /
• pp.224-227
• /
• 2004

The cement can be influenced by the temperature. Especially, when it is cold weather, it causes some problems in such properties as mixing, placing and curing of concrete. According to the Concrete Standard Specification(2003), in case of the average daily outdoor temperature below $4^{\circ}C$, it recommends to use the cold weather concrete. In this research, the on-site quality characteristics of the cold weather concrete using high early strength portland cement(Type III cement) were studied. As a result, the cold weather concrete using high early strength portland cement can obtain its excellent properties and benefit the cost of construction.

• Computers and Concrete
• /
• 제6권5호
• /
• pp.391-401
• /
• 2009

This paper presents a study of the strength and chloride penetration of blended Portland cement mortar containing ground palm oil fuel ash (POA) and ground river sand (GS). Ordinary Portland cement (OPC) was partially replaced with POA and GS. Compressive strength, rapid chloride penetration test (RCPT) and chloride penetration depth of mortars were determined. The GS only asserted the packing effect and its incorporation reduced the strength and the resistance to chloride penetration of mortar. The POA asserted both packing and pozzolanic effects. The use of the blend of equal portion of POA and GS also produced high strength mortars, save cost and excellent resistance to chloride penetration owing to the synergic effect of the blend of POA and GS. For chloride depth, the mathematical model correlates well with the experimental results. The computer graphics of chloride depth of the ternary blended mortars are also constructed and can be used to aid the understanding and the proportioning of the blended system.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.603-606
• /
• 2005

Strength development of low heat portland cement(Type IV) concrete according of addition of fly-ash in high strength range is tested. In this study strength development according to water-binder ratio, strength development according to age, effect of fly ash are tested. This study tests effect of low heat portland cement in high strength range concrete and provide guide line concrete mix design for later study and construction.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
• /
• pp.445-448
• /
• 2006

In order to control the temperature crack of massive dam concrete, the selection of appropriate materials like binder, aggregates etc., is essential. To select the optimal mix proportion, ordinary portland cement(Type I) plus 25% of fly ash and low heat portland cement(Type IV) are used as binder, and 80mm of coarse aggregates are used to reduce the amount of binder and compare the compressive strength, hydration temperature and crack index. The results of this study are as following. 1. The strength of Type IV cement is advantageous on the long-term age. 2. According to the temperature measured on mock-up$(1.5m{\times}1.5m{\times}1.5m)$, and realized the thermal analysis, the Type IV cement carried out advantageous to control the thermal crack.

• 한국세라믹학회지
• /
• 제22권4호
• /
• pp.21-25
• /
• 1985

For studying the influence of addition of Polyvinyl alcohol (PVA)-montmorillonite complex on the hydration of Portland cement the PVA-montmorillonite derivatives were prepared in advance an characterized system-of Portland cement the PVA-montmorillonite derivatives were prepared in advance and characterized systema-tically. PVA with the polymerizationdegree ranging from 500 to 2000 have been intercalated into the lamellar structure of hydrated montmorillonites which were fractionated under 2㎛ by Stock's rule. In all cases the constant basal spacing of ∼20Å was determined whatever the molecular weight of PVA used. And the carbon chain orientation of PVA in the interfoliar space has been deduced to be parallel with bilayer structure.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
• /
• pp.44-47
• /
• 2003

High flowing concrete has not spread whole in the normal concrete structure, because it requires special quality control technique. Recently owing to the lack of natural resources and reinforcement of environmental standard, the construction cost of cement is rapidly increased. Also ready mixed concrete industry has gone through various economical difficulty as the manufacture cost of concrete is increased. So, the purpose of this study is to evaluate the qualities of middle fluidity concrete using the fly-ash and portland blast-furnace slag cement in order to decrease the amount of cement and resolve the problem of the quality control of high flowing concrete and the manufacture cost. The results of this study show that it reduces the amount of addition of superplasticizer and develope properties of concrete to the use the fly-ash and portland blast-furnace slag cement.