Cementitious materials can be reinforced by adding different fibers. However, the effect of different fiber reinforcements on the mechanical properties of cement-based materials remains to be further studied. This paper studies the influencing factors of different fiber cement-based materials by combining experimental and theoretical methods. The tests used carbon fiber, glass fiber, and polyvinyl alcohol (PVA) fiber-reinforced cement-based materials. The addition ratios of fibers are 0%, 0.5%, and 1% by volume respectively. The compressive strength, bending strength, and drying shrinkage are studied for 3 to 28 d. The relationship between bending strength, compressive strength, dosage, and shrinkage is analyzed. The test results show that carbon fiber cement-based materials’ bending, and compressive strength increase the fastest, followed by glass and PVA fibers. The presented mathematical model accurately predicted the strength of the three fiber cement-based materials at different curing times. Compared to glass fiber and PVA fiber, carbon fiber shrinks less. It can be shown that the fiber significantly affects the early strength change of the fiber cement-based material by changing the shrinkage size of the fiber-cement-based material. The bending strength of carbon fiber, glass fiber, and PVA fiber increases with the increase of fiber volume fraction. On the other hand, the compressive strength increases and then decreases. Mechanical tests show that carbon fiber has the best reinforcement effect. The number of fibers, center spacing, and ultimate tensile length are all important factors that affect the strength of different fiber cement-based materials. Moreover, applied ABAQUS software established compression and bending finite element models of fiber-cement composites. It can predict the mechanical performance concerning fiber cement-based materials’ different types and volume fractions.

Recycled powder (RP) is a by-product of preparing recycled aggregates from construction waste through debris removal, step-by-step crushing, screening, and mechanical strengthening. It is a fine powder with a particle size of less than 75 μm. Reasonable use of RP can increase the utilization rate of construction waste and reduce dust pollution. This study introduces the current research status of RP. It describes the source of RP; the activation mode of activity; the effect on several aspects, such as early performance and mechanical properties of cement-based materials; and its mechanism of action in light of the research and development. Moreover, the linear regression analysis method was used to obtain the mathematical model between the content of RP and the performance of cement-based materials. The correlation degree between the content of RP and the performance of cement-based materials was obtained based on the gray relation analysis method. It was concluded that the change of the content of RP had the most significant influence on the compressive strength of foamed concrete over 28 d. Finally, some feasible suggestions and prospects for RP are provided.

Epoxy resin, CFRP (Carbon Fiber Reinforced Polymer) sheet, and concrete flexural specimens are selected to study the durability of carbon fiber strengthened cementitious materials in a cold region. Two exposure environments, chloride immersion and salt-freeze coupling, are set up, and the mechanical deterioration is discussed utilizing a microscopic observation mechanical test and finite element analysis. The damage to the epoxy resin, CFRP sheet, and concrete exerts a more severe performance degradation in the salt-freeze coupling environment when compared with the chlorine salt immersion environment. The freeze–thaw action destroys the bonding surface of CFRP and concrete based on the microscope observation. The flexural strength of the specimens strengthened with CFRP is 3.6 times higher than that of the specimens without CFRP, while the degradation rate is only 50%. These observations show that the strengthened CFRP effectively improves the cementitious material’s flexural performance in the cold region. The finite element model of epoxy and CFRP subjected to chloride immersion and salt-freeze coupling environment is established. The degradation formula of bond performance between CFRP and concrete is proposed. In addition, the flexural mechanical numerical model is established with and without CFRP strengthened concrete, respectively. Research results provide a technical reference for applying CFRP reinforced cementitious materials in a cold region.

Three reinforcement ratios (0, 50, and 100%) of carbon fiber reinforced plastics (CFRP) were selected to improve the mechanical properties of recycled brick concrete in this study. Utilizing axial compression test, X-ray diffractometer analysis, the evolution of parameters such as compressive strength, peak stress, and elastic modulus of reclaimed concrete were analyzed. The reclaimed brick concrete’ stress distribution and damage mechanism were revealed. The aggregate internal failure and CFRP reinforcement effect mechanism are discussed. The finite element model of red brick concrete reinforced by CFRP under uniaxial compression is established. The constitutive model for CFRP-reinforced recycled brick concrete is proposed.

During the ice-breakup period in cold regions, the impact of drifting ice floes on bridge piers readily induces extreme ice loads and structural damage, and because the ice is transported continuously by the flow, a pier is subjected to a sustained crushing process rather than a single free collision. Conventional protective techniques suffer from insufficient durability, whereas fiber-reinforced polymer (FRP) offers protective advantages owing to its light weight, high strength, and corrosion resistance. However, the differences in ice-impact protective performance among carbon (CFRP), glass (GFRP), basalt (BFRP), and aramid (AFRP) fiber composites remain unclear. In this study, ANSYS/LS-DYNA is employed to construct an explicit dynamic finite element model of continuous ice-floe impact on an FRP-strengthened bridge pier, in which the sustained driving action of the flow is represented by a constant-velocity boundary prescribed at the trailing edge of the ice. The elastic constants of ice are calibrated and the material parameters verified against published ice-concrete collision test data, reducing the relative error of the maximum impact stress from 22.5% to 7.89%; a purpose-designed scaled-model ice-pier impact flume test is further used for qualitative verification of the collision process. On this basis, 20 full-factorial parametric cases are designed to systematically examine the influences of ice-floe velocity, ice volume, and FRP type on the impact force, stress distribution, displacement response, and energy dissipation. Within the investigated parameter ranges and modeling assumptions, the results show that: (1) the peak impact force is governed mainly by the effective ice-pier contact area and the crushing strength of ice; for the unstrengthened pier, doubling the ice velocity raises the peak force by only 3.3–4.7%, and doubling the ice volume changes the peak force by only 1.5–2.7%; (2) the reduction in the peak impact force by FRP is strongly dependent on the ice condition, material differences appearing only under the small-volume, low-velocity condition (21.7–29.5%) and amounting to less than 0.1 percentage point under the other conditions; in terms of the mean impact force, CFRP is the only scheme that achieves a reduction under all ice conditions, with a mean reduction of 18.0% over the four conditions, superior to AFRP (12.3%), GFRP (9.5%) and BFRP (9.1%), although this ranking applies to the 5 mm equivalent shell and is thickness-dependent; (3) at the representative instant t = 0.2 s the peak von Mises stress of the pier decreases from 3.201 MPa to 1.111–1.693 MPa, a reduction of 47.1–65.3%, showing a far higher sensitivity to FRP type than the peak impact force; (4) the peak stress in the four FRP sheets amounts to only 0.21–0.36% of their fiber-direction tensile strength and their internal energy is close to zero, indicating that, within the present configuration (a 5 mm equivalent FRP shell held against the pier by a frictional, unbonded contact interface), the protective effect of FRP derives mainly from local stiffness enhancement and load diffusion rather than from tensile load carrying or energy absorption. The above mean impact forces and energy quantities are values truncated at t = 0.5 s. This study quantifies the differences in ice-impact protective performance among FRP types and provides a numerical reference for FRP selection and ice-resistant design of bridge piers in cold regions within the investigated parameter ranges. These findings, in particular the weak velocity sensitivity, are conditional on the adopted rate-independent ice model, which does not represent the strain-rate dependence of ice strength.