Effects of viscosity modifying agents on fresh and hardened properties of concrete

Name: Neupane, Upendra

keyword: Bleeding

LCSH: Concrete -- Testing

; Pressurized dewatering

LCSH: Strains and stresses

; High pressure

; Bored piles

; Viscosity modifying agents

Abstract: This study emphasizes the effects of viscosity modifying agents (VMAs) on fresh and hardened properties of concrete. The properties of concrete were examined in terms of initial slump, bleeding, air content, setting time, compressive strength of concrete, and dewatering of mortar under high pressures. Additionally, the effect of surfactant type VMA on blending between concrete and bentonite fluid was also examined. Two different types of VMA, which are a surfactant type and a starch ether type with various dosages were used with or without water reducing admixtures in the tested mortar and concrete mixtures. From the experiments, it was found that the tested surfactant type VMA was not compatible with type D admixtures. The surfactant type VMA with type F admixtures increased the initial slump and air content, significantly reduced the bleeding, slightly reduced the compressive strength and had a negligible effect on setting time of the concrete. However, surfactant type VMA slightly increased the setting time of fly ash concrete. Furthermore, it effectively reduced blending between bentonite fluid and concrete. On the other hand, the use of starch in concrete mixtures slightly increased the air content, moderately reduced the bleeding, and slightly reduced the compressive strength of concrete. The increase of air by starch is less significant when compared to the case of surfactant type VMA. In the case of mortar test, the addition of surfactant type VMA slightly increased the mortar flow and v-funnel flow time due to enhancement of the air content and viscosity, respectively, of the mixtures, whereas starch ether decreased the mortar flow and increased the v-funnel time due to viscosity increase. By using dosages of surfactant type VMA equal to or higher than 3%, the pressurized dewatering of the mortars was significantly reduced. Furthermore, the use of surfactant type VMA in mortar mixtures with polycarboxylate based superplasticizer effectively reduced the pressurized dewatering of mortar whereas use of surfactant type VMA with naphthalene based superplasticizer was ineffective to reduce the dewatering of mortars under high pressure. Similarly, the use of starch in mortar mixtures was ineffective to reduce dewatering of mortars under high pressure

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Parnthep Julnipitawong

Role: advisor

Created: 2016

Modified: 2021-06-01

Issued: 2021-06-01

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2016.520

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Engineering and Technology

Grantor: Thammasat University

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