1. Effect of water absorption of SAP on the rheological properties of cement-based materials with ultra-low w/b ratio.
- Author
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Ma, Xianwei, Yuan, Qiang, Liu, Jianhui, and Shi, Caijun
- Subjects
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ABSORPTION , *RHEOLOGY , *THIXOTROPY , *CEMENT , *VISCOSITY , *SHEAR strength - Abstract
Highlights • Rheological properties have a good relation with the absorption of SAP. • The thixotropy shows the effect of SAP absorption behavior compared with plastic viscosity and maximum shear stress. • Large SAP's particles led to a high absorption rate and a long absorption time. Abstract Superabsorbent polymer (SAP) is an important internal curing agent for concrete with low or ultra-low water-to-binder ratio (w/b). When SAP is added, it will absorb water from fresh concrete fast. Thus, water absorption of SAP will affect the rheological properties of cement-based materials, especially at low w/b. Moreover, SAP with different particle size has a different absorption rate which will also affect the rheological properties. In this paper, two SAPs with different particle size are used to investigate its effects on the maximum shear stress, yield stress, plastic viscosity and thixotropy of cement-based materials within 80 min. Basic w/b of 0.18 was specified as reference values. Rheological results show that the absorption of SAP changed the evolution of yield stress, plastic viscosity and thixotropy of fresh mortar with time. Large SAP's particles led to a high absorption rate and a long absorption time which increased the yield stress and plastic viscosity. The above effects of SAP are closely related to the availability of water near SAP in cement mortar which causes to be a nonlinear relationship between the amounts of SAP and extra water required. In addition, the amount of extra water should be adjusted according to particle size of SAP and the addition level of SAP. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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