Influence of polyvinyl alcohol fiber and fly ash content on compressive creep properties of high ductility cementitious composites

Bo Chen,Xiongfeng Wang,Lihui Zhang,Wenxiao Zhang,Liping Guo,Yin Bai,R Ruan

doi:10.1051/e3sconf/202127202014

Abstract

The influence of polyvinyl alcohol (PVA) fiber volume fraction and fly ash content on the creep behavior of high ductility cementitious composites (HDCC) under compression was investigated. For this investigation, the creep behavior of four HDCC groups with cube compressive strength of 30–50 MPa, PVA fiber volume fraction of 1.5% and 2.0%, and fly ash content of 60% and 80% at 7 d and 28 d loading periods, respectively, were evaluated. A compressive creep model, which reflects the loading age and holding time, was established. The results revealed that when the load was applied at 7 d and 28 d, and then maintained for 245 d, the specific creep of HDCC ranged from 95×10-6/ MPa to 165×10-6/ MPa and from 59×10-6/ MPa to 135 × 10−6/ MPa, respectively. The corresponding creep coefficients ranged from 1.48 to 2.25 and from 1.10 to 1.94, respectively. The PVA fiber volume fraction and fly ash content were the main factors affecting the specific creep of HDCC, which increased with increasing fiber fraction and fly ash content. Under short-term loading, the fiber volume fraction played a leading role in the specific creep, and the fly ash content played the leading role during long-term loading. Furthermore, the specific creep and creep coefficient decreased significantly with increasing loading age. The classical creep model described by a power exponent function is suitable for HDCC.

Highlights

Concrete creep refers to an increase in deformation of concrete with time under a long-term constant load
High ductility cementitious composites (HDCC) is a kind of fiber-reinforced cementbased composites, which are based on the theory of micromechanics and fracture mechanics, and have been systematically designed to exhibit high ductility under tensile and shear loads.[1]
HDCC differ significantly from the ordinary concrete in raw materials, which are mainly reflected in the fact that: the maximum aggregate size of HDCC is only 1.18 mm or less, coarse aggregates are absent, while the maximum fine aggregate size of ordinary concrete is 5 mm, and the coarse aggregate size ranges from 5 mm to 31.5 mm or greater; the maximum volume content of the polyvinyl alcohol (PVA) fiber in HDCC ranges from 2.0% to 3.0% or greater, which is significantly higher than the 0.1% fiber volume content of ordinary concrete; the maximum fly ash content of HDCC is 40% to 80%, which is considerably higher than the 10%

Summary

Introduction

Concrete creep refers to an increase in deformation of concrete with time under a long-term constant load. Creep will lead to the elimination of stress concentration from the concrete structure, lead to a uniform stress redistribution, and reduce the temperature stress of concrete. The creep will increase the deflection of flexural members by 2-3 times, increase the additional eccentricity of slender columns, and lead to a prestress loss of prestressed members. HDCC differ significantly from the ordinary concrete in raw materials, which are mainly reflected in the fact that: the maximum aggregate size of HDCC is only 1.18 mm or less, coarse aggregates are absent, while the maximum fine aggregate size of ordinary concrete is 5 mm, and the coarse aggregate size ranges from 5 mm to 31.5 mm or greater; the maximum volume content of the PVA fiber in HDCC ranges from 2.0% to 3.0% or greater, which is significantly higher than the 0.1% fiber volume content of ordinary concrete; the maximum fly ash content of HDCC is 40% to 80%, which is considerably higher than the 10%

Methods

Results

Conclusion