신규 증점제를 사용한 모르터의 유동성에 관한 연구

임서형,서원택 진주산업대학교 2000 산업과학기술연구소보 Vol.- No.7

The purpose of this study is to estimate the fluidity of mortar with a new viscosity modifying admixture. For this pupose, selected test variables were the ratio of water to cement and cement to fine aggregate, contents of superplasticizer and viscosity modifying admixture. As a rusult of this study, it is considered that the loss of flow with time of mortar occurs much faster with a superplasticizer and no viscosity modifying admixture. Also, it has been found that addition of viscosity modifying admixture to mortar modfies its fluidity and reduces its segregation by increasing the mortar viscosity.

Influence of viscosity modifying admixtures on the rheologicalbehavior of cement and mortar pastes

R. Bouras,A. Kaci,M. Chaouche 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.

Influence of viscosity modifying admixtures on the rheological behavior of cement and mortar pastes

Bouras, R.,Kaci, A.,Chaouche, M. 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.

폴리카본산계 고성능 감수제와 증점제 조합에 따른 보통강도 고유동 콘크리트의 유동 및 강도특성에 관한 실험적 연구

공태웅(Kong, Tae-Woong),이한승(Lee, Han-Seung) 대한건축학회 2021 대한건축학회논문집 Vol.37 No.4

High fluidity concrete has a high level of fluidity with the segregation resistance and the self-compacting property without the extra work for compaction. Therefore this concrete represents high quality concrete with excellent workability and enables the easy production of heavily reinforced concrete structures of complex geometry. Despite its obvious advantages, the high cost of high fluidity concrete prevents its wider use. Also the application of typical high fluidity concrete is limited in the normal strength range (18~35 ㎫) because of the uneconomical strength development due to large amount of binder. It is required to design the formulation of an economical binders, proper materials and mixtures for normal strength and high fluidity in order to expand the usability of such high fluidity concrete for general application. But if the usage of binders is low in concrete, it is reduced the fluidity and segregation resistance due to the decrease in self-compacting reduction by lack of viscosity. The aim of the study is to evaluate the fluidity and strength of high fluidity concrete for normal strength range using the combination of polycarboxylate viscosity modifying admixture (P-VMA) and methyl cellulose viscosity modifying admixture (C-VMA). To improve the fluidity of concrete, this paper investigated the effects of VMA on the slump flow, passing ability, self-compacting and segregation resistance. In addition, the effect of VMA on compressive strength was investigated. The dosage of P-VMA and C-VMA in the mixtures was 0.2%, 0.4%, 0.6% and 0.1%, 0.2%, 0.3% by weight of the total biders, respectively. As a result of this study it has been found that addition of VMA to concrete improves its fluidity and segregation resistance by increasing the viscosity of concrete, but the compressive strength decreased with increase of VMA.

일반강도 콘크리트의 재료분리 발생 방지를 위한 증점제 사용 범위 분석

이유정 ( Lee Yu-jeong ),한동엽 ( Han Dong-yeop ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.2

The purpose of this study is to achieve a sufficient fluidity without segregation for normal compressive strength grade concrete mixture. The major obstacle of achieving fluidity of normal compressive strength grade concrete mixture is segregation. Therefore, in this research, the proper use of VMA was suggested to prevent segregation.

일반강도 콘크리트의 재료 분리 발생 방지를 위한 증점제의 성능 분석

이유정 ( Lee Yu Jeong ),이향선 ( Lee Hyang Sun ),한동엽 ( Han Dong Yeop ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.1

The purpose of this study is to achieve a sufficient fluidity without segregation for normal compressive strength grade concrete mixture. The major obstacle of achieving fluidity of normal compressive strength grade concrete mixture is segregation. Hence, in this research, VMA was used to prevent segregation.

중유동 콘크리트의 재료분리 경계 판단을 위한 레올로지 정수 범위 분석

이유정 ( Lee Yu Jeong ),김영기 ( Kim Young Ki ),한동엽 ( Han Dong Yeop ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.1

The purpose of this study is to analyze the extent of the rheology parameters at the segregation boundary of mid-range workability concrete. In addition, it was intended to present the extent of the rheology parameters of the normal strength concrete with segregation resistance using the determination of segregation occurrence of concrete and the use of the rheology parameters. However, it was confirmed that segregation occurs even if the measured rheology parameters is in the range of the suggested rheology parameters. Therefore, it is determined that the conditions under which segregation occurs will provide fundamental data that can be rheological defined. Additional studies are also needed on the relationship between rheological parameters and segregation.

배합변수가 고유동 콘크리트의 특성에 미치는 영향

이근수(Lee Keun-Su),최열(Choi Yeol) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.5

High-fluidity concrete(HFC) or Self compacting concrete(SCC) is considered as a new generation of concrete which can be used widely in case of heavily reinforced or relatively larger size of structural members in concrete structures without any vibration efforts. The researches on HFC are being conducted to verify its flowability, filling ability and segregation resistance since late 1980. There are a variety of factors that affect on these characteristics such as water-binder ratio, SP(superplasticizer) and VMA(viscosity modified admixture) contents. The present work is aimed to figure out the variations of flowability, filling ability, passing ability and compressive strength of HFC in accordance with water-binder ratio and contents of mixing variables. From the test results, the slump flow is increased linearly when water/binder and SP ratio increased within significant segregation is not occurred. Also the compressive strength is decreased linearly when water-binder ratio and SP ratio increases, and increased linearly when VMA content increases. However, passing ability showed an irregular change under various mixing variables.

배합변수가 고유동 콘크리트의 특성에 미치는 영향

이근수,최열 대한건축학회 2010 大韓建築學會論文集 Vol.26 No.5

<P>High-fluidity concrete(HFC) or Self compacting concrete(SCC) is considered as a new generation of concrete which can be used widely in case of heavily reinforced or relatively larger size of structural members in concrete structures without any vibration efforts. The researches on HFC are being conducted to verify its flowability, filling ability and segregation resistance since late 1980. There are a variety of factors that affect on these characteristics such as water-binder ratio, SP(superplasticizer) and VMA(viscosity modified admixture) contents. The present work is aimed to figure out the variations of flowability, filling ability, passing ability and compressive strength of HFC in accordance with water-binder ratio and contents of mixing variables. From the test results, the slump flow is increased linearly when water/binder and SP ratio increased within significant segregation is not occurred. Also the compressive strength is decreased linearly when water-binder ratio and SP ratio increases, and increased linearly when VMA content increases. However, passing ability showed an irregular change under various mixing variables.</P>

고로슬래그 미분말을 혼입한 보통강도 고유동 콘크리트 배합에 관한 실험적 연구

장현오(Jang, Hyun-O),지남용(Jee, Nam-Yong) 대한건축학회 2013 大韓建築學會論文集 : 構造系 Vol.29 No.6

High fluidity concrete is the concrete that has a high level of fluidity without the separation of materials while it is not hardened and has the self-compacting property without the extra work for compaction. In order to expand the usability of such high fluidity concrete for general usage, the formulation of an economical binder through the recycling of resources and reasonable mixing conditions for normal strength and high fluidity concrete are required. Therefore, this study formulated concrete binders at Level Six using ground granulated blast furnace slag for W/B 0.45 and 0.55, and then, performed a fluidity securing experiment according to the addition rates of a air entraining and high-range waterreducing agent. Accordingly, for the mixes in which the separation of materials occurred, the fluidity securing experiment was run after adding a viscosity agent in the concrete, which was 0.05% of the amount of the powder. According to these results, the optimal mixing ratios regarding the mixing of normal strength and high fluidity concrete using ground granulated blast furnace slag were BFS 15% and a air entraining and high-range waterreducing agent 1.25% for W/B 0.45, and were BFS 30% and a air entraining and high-range waterreducing agent 0.75% for W/B 0.55.