Abstract
Supplementary cementitious materials (SCMs) have been widely used to replace cement in UHPC, which benefits to reducing CO2 emissions and declining construction costs. However, the influence of SCMs on the dynamic compressive properties of Ultra-high performance concrete (UHPC) paste has not been well understood. Here, the workability, pore structure, quasi-static compressive strength and dynamic compressive properties of UHPC paste with different SCM systems are comprehensively studied. The results show that the substitution of cement by ground granulated blast furnace slag (GGBS) and limestone powder (LP) increases workability. With the substitution rate of 10% LP, the microstructure of M2 becomes denser. With the further increasing replacement of GGBS and LP, the porosity increases, while the quasi-static compressive strength and dynamic compressive properties trend to decrease, but the extent is limited. The compressive properties such as dynamic compressive strength, dynamic increase factor (DIF), peak strain and toughness are highly dependent on the strain rate. An applicable DIF model for UHPC is established at the strain rate of 53.9 - 170.7 s−1. The fractal dimension increases with the rising of GGBS and LP. Additionally, a positive linear relationship is observed between the fractal dimension and the denary logarithms of the strain rate.
Highlights
Ultra-high-performance concrete (UHPC) is a relatively advanced cementitious composite with superior mechanical properties, excellent durability, and good impact resistance [1,2,3]
The results show that the substitution of cement by ground granulated blast furnace slag (GGBS) and limestone powder (LP) increases workability
Fluidity is an important property of Ultra-high performance concrete (UHPC), and insufficient fluidity will have a negative impact on its mechanical properties [42]
Summary
Ultra-high-performance concrete (UHPC) is a relatively advanced cementitious composite with superior mechanical properties, excellent durability, and good impact resistance [1,2,3]. The low water-to-binder ratio (0.16 ~ 0.22) and high cement content are often used to achieve ultra-high strength, resulting in high cost, energy consumption and intensive CO2 emission [4]. Very low water-to-cement ratios are generally utilized to decrease the porosity and promote the strength in UHPC. The matrix plays an essential role in the dynamic performance of UHPC It is of great intrinsically scientific and engineering significance to study the influence of SCMs on the dynamic compressive properties of UHPC paste for analyzing and designing UHPC structures under impact loads. The workability is of great signif icance to engineering applications and the pore structure of UHPC pastes can benefit the comprehension of quasi-static compressive strength and dynamic compressive properties.
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