The Mechanical Characteristics of High-Strength Self-Compacting Concrete with Toughening Materials Based on Digital Image Correlation Technology

Abstract

Brittle fracture is a typical mechanical characteristic of high-strength self-compacting concrete, and the research on its toughening modification remains the highlight in the engineering field. To understand the effect of toughening materials (including polymer latex powders, rubber particles, and polyethylene fibers) on the mechanical behavior of C80 high-strength self-compacting concrete under static loading, the failure mode, mechanical strength, strain field, and crack opening displacement (COD) of prepared high-strength self-compacting concrete under compressive, splitting, and flexural loads were studied based on digital image technology (DIC). The corresponding mechanism is also discussed. The results show that the hybrid of polymer latex powders, rubber particles, and polyethylene fibers can increase the crack path and inhibit the development of macrocracks in concrete, thus turning the fracture behavior of concrete from brittle to ductile. The addition of toughening materials reduced the compressive and flexural strengths of high-strength self-compacting concrete, but it increased the splitting strength. DIC showed that the incorporation of toughening materials promoted the redistribution of strain and reduced the degree of strain concentration in high-strength self-compacting concrete. The evolution of COD in high-strength self-compacting concrete can be divided into two stages, including the linear growth stage and the plastic yield stage. The linear growth stage can be extended by incorporating toughening materials. The COD and energy absorption capacity of concrete were enhanced with the addition of toughening materials, and the best enhancement was observed with the hybrid of polymer latex powders, rubber particles, and polyethylene fibers. Overall, this research provides a reference for exploring effective technical measures to improve the toughness of high-strength self-compacting concrete.

Keywords: crack; digital image correlation (DIC); high-strength self-compacting concrete; strength; toughening materials.

Figure 1

Particle size distributions.

Figure 2

Test device of (a) compressive strength test, (b) splitting strength test, and (c) three-point bending test.

Figure 3

Failure patterns of specimens under (a) compressive, (b) splitting, and (c) three-point bending actions.

Figure 4

(a) Compressive strength, (b) splitting strength, and (c) flexural strength of specimens incorporating toughening materials.

Figure 5

The influence rates of toughening materials on the strength of concrete.

Figure 6

The ratios of flexural strength to compressive strength (f_f/f_c) of specimens incorporating toughening materials.

Figure 7

Strain fields under compressive loads of specimens incorporating toughening materials.

Figure 8

Strain fields under splitting loads of specimens incorporating toughening materials.

Figure 9

Strain fields under flexural loads of specimens incorporating toughening materials.

Figure 10

A schematic diagram of the virtual extensometers of a specimen (taking specimen CAR as an example).

Figure 11

The relationships between the COD and P/P_max of specimens (a) C0, (b) CAR, and (c) CARF.

Figure 12

The load–COD curves of specimens with different toughening materials.