The Development and Application Status of Advanced Cement-Based Materials

1. Introduction

Cement-based materials exhibit excellent properties, such as plasticity, castability, high compressive strength, fire resistance, durability, and cost-effectiveness [1,2]. As a result, they are now among the most widely utilized building materials globally and are vital for infrastructure development in contemporary society [3]. However, traditional cement-based materials tend to be brittle and possess drawbacks such as low tensile strength and inadequate toughness [4]. Cracks in cement-based materials can significantly heighten the risk of water, carbon dioxide, oxygen, chloride ions, and other harmful substances infiltrating their internal structure. This unwanted intrusion not only accelerates the deterioration of the material but also compromises the durability of the entire structure, jeopardizing the overall service life of the project. To combat these issues, it is crucial to enhance the mechanical properties and durability of cement-based materials. By integrating reinforcing materials such as fibers and admixtures, we can make significant advances in creating more resilient structures that stand the test of time.

To improve the low tensile ductility of concrete, fibers are added to create fiber-reinforced concrete (FRC), which optimizes its performance [5]. These fibers help prevent the initiation of cracks, effectively reducing both their size and quantity. During the stress process, the fibers not only inhibit the growth and spreading of cracks but also reduce stress concentration at the crack tip. As a result, they significantly enhance the tensile strength, deformation capacity, and resistance to dynamic loads in concrete. Numerous factors play a vital role in determining the tensile strength of fiber-reinforced concrete (FRC), with the characteristics of the fibers, the substrate, and the fiber content being the most significant [5,6,7,8,9]. In the realm of concrete, fibers act as essential crack arresters, effectively dissipating localized internal stress. By interrupting the pathways of developing cracks caused by these stresses, as well as mitigating the effects of existing cracks, fibers not only strengthen the material but also provide a preventive mechanism against the formation of plastic shrinkage cracks during the crucial initial curing phase. Incorporating fibers into concrete is not just a choice; it is a powerful strategy for enhancing durability and longevity. From the perspective of material properties, the mechanical behavior of the interface between fiber and matrix has become an important topic in micromechanics research into advanced composite materials. Fruitful results have been achieved in both theory and experiment [5,6,7,8,9]. Researchers and experts have made significant strides in enhancing the engineering properties of concrete by integrating a variety of fibers. This innovative approach aims to solve common issues linked to high fiber content in conventional fiber concrete—such as excessive weight and the problematic knotting effect—while simultaneously boosting its toughness. By embracing these advancements, we can unlock the full potential of concrete, making it stronger and more efficient for future applications [10,11,12,13,14].

On the other hand, cement manufacturing is an energy-intensive and water-intensive process, and the carbon dioxide it emits seriously harms the environment, thus raising sustainability issues [15,16,17]. To promote the sustainable development of ultra-high-performance cement-based materials, it is essential to focus on their design and proportions. For instance, increasing the cement content in ultra-high-performance concrete (UHPC) can lead to higher production costs and impact both the heat of hydration and volume stability. Moreover, increasing cement content makes the sustainability problem worse. Therefore, incorporating pozzolanic materials to partially replace cement is beneficial for conserving energy and reducing carbon emissions. This approach also enhances the fresh mix properties, mechanical performance, and durability of the concrete materials [18,19,20]. In addition, since the water–cement ratio of UHPC is very low, only part of the cement is hydrated, and the unhydrated cement can be replaced by fine particles. For example, up to 30%, 36%, and 40% (volume) of cement in UHPC can be replaced by crushed quartz, fly ash, and slag, respectively, without compromising its compressive strength [21]. The addition of nanoparticles made of silica (SiO₂), alumina (Al₂O₃), iron oxide (Fe₂O₃), titanium dioxide (TiO₂), or zirconium dioxide (ZrO₂) can fill the pores between micron-sized cementitious materials and fine aggregates, thereby reducing the porosity and achieving a higher particle packing density [22,23]. These materials are essential nuclei for the cement phase, greatly enhancing hydration and driving the formation of calcium silicate hydrates through the Pozzolanic Reaction. This process significantly reduces calcium leaching and eliminates weak zones caused by calcium hydroxide, ensuring stronger and more resilient cement structures [24,25].

Considering life cycle costs, the high toughness and damage tolerance of UHPC significantly reduces future maintenance, repair, and reinforcement expenses. As engineering construction worldwide shifts toward high quality, UHPC offers numerous advantages. These include enhancing environmental protection, conserving energy, reducing labor needs, improving construction quality, and advancing construction technology. Thus, UHPC is poised to become an essential construction material.

2. An Overview of Published Articles

The progress of advanced cementitious materials depends on innovative approaches to enhance their mechanical properties, sustainability, and durability. Janus et al. [26] proposed a new method to obtain photoactive cement. During the cooling process of cement clinker, amorphous TiO₂ is added to the cooler. Amorphous TiO₂ was obtained from a device that produces titanium dioxide using the sulfuric acid process. In the study, amorphous TiO₂ was added to the clinker at 300, 600, 700, and 800 °C. The properties of the resulting cement were tested for flexural and compressive strength. Initial and final setting times were also measured. The adhesion of the resulting materials to concrete blocks, ceramic tiles, and gypsum boards was evaluated as well. The photocatalytic activity of the obtained materials in the decomposition of NO and BTEX (decomposition of benzene, toluene, ethylbenzene, p-, m-, and o-xylene) was studied under ultraviolet irradiation. The results indicated that cement with different percentages (by weight) of TiO₂ added to the clinker at 700 °C exhibited the highest photocatalytic activity and the best mechanical properties.

Premature debonding between carbon fiber-reinforced polymer (CFRP) and concrete often results in a significant reduction in the load-bearing capacity of the system. This failure mode is usually caused by insufficient interfacial bonding, thus hampering the effectiveness of CFRP in reinforcing the structural performance of concrete components. To this end, Babba et al. [27] studied the effect of silica sand on the mechanical and adhesion properties of epoxy resin composites. Firstly, the physical and mechanical properties of epoxy resin composites were studied when the volume fraction of silica sand varied from 0% to 15%. Subsequently, the effectiveness of these composites as sealing materials to enhance the bond strength between CFRP and concrete was investigated. The study showed that the addition of 10% silica content improved the mechanical properties of epoxy resin, with the tensile strength increasing from 29.47 MPa to 35.52 MPa and the elastic modulus increasing from 4.38 GPa to 5.83 GPa. In addition, silica sand enhanced the bond strength between CFRP and concrete, and the pull-off force increased from 14.21 kN to 18.79 kN. This confirms that silica particles improve the surface roughness and interlocking, contributing to better load distribution and stress transfer at the interface.

Masonry structures are vulnerable to damage and collapse during earthquakes. To address this issue, researchers are exploring the application of fiber-reinforced mortar as a strengthening overlay system. Almeida et al. [28] investigated the use of synthetic polyacrylonitrile (PAN) fibers as a reinforcement material in natural hydraulic lime (NHL) mortar. Their study aimed to understand the impact of these fibers on both the fresh behavior and mechanical properties of the mortar. Research has shown that the fresh performance of fiber-reinforced mortar (FRM) is suitable for applications with fiber volume fractions below 0.50%. The increase in fiber volume fraction has different effects on compressive strength and flexural strength, with compressive strength decreasing and flexural strength increasing. The maximum compressive strength achieved was 13.3 MPa with a fiber content of 0.25%. In contrast, the maximum flexural strength recorded was 6.70 MPa at a fiber content of 1.00%. Both compressive and flexural toughness, which relate to the material’s performance after cracking, increase as the fiber content rises. Even with a fiber content as low as 0.25%, there is a significant enhancement in the material’s ability to dissipate energy.

3. Conclusions

The performance of cement-based materials can be improved using innovative methods and additives. The addition of titanium dioxide (TiO₂) to cement enhances its environmental performance by effectively degrading harmful pollutants while also maintaining the structural integrity required for construction applications. Additionally, incorporating silica sand into epoxy resin formulations strengthens the material and optimizes the performance of composite structures. Consequently, the use of such modified epoxy resins could lead to more durable and resilient applications in construction and engineering fields. The fibers were able to enhance the workability and bonding properties of the mortar mixtures at lower fiber volume fractions without significantly altering their setting time. Further research could explore these materials’ long-term stability and performance under realistic conditions.