Ultra-high-performance concrete (UHPC) is a type of cement-based composite for new construction and/or restoration of existing structures to extend service life. UHPC features superior workability, mechanical properties, and durability compared with conventional concrete. However, some challenges limit the wider application of UHPC, such as low workability for large-volume production, high autogenous shrinkage, insufficient flexural/tensile properties, and unpredictable durability after concrete cracking. Therefore, this paper reviews the state-of-the-art technologies for developing UHPC mixtures with improved properties. This review covers the following aspects: (1) the existing design methodologies; (2) the typical ingredients (e.g., binders, aggregates, chemical admixtures, and fibers) for preparation of UHPC and the underlying working principals; (3) the technologies for improving and controlling key properties (e.g., workability, autogenous shrinkage, compressive performance, tensile/flexural properties, and durability); and (4) the representative successful applications. This review is expected to advance the fundamental knowledge of UHPC and promote further research and applications of UHPC.

New development of ultra-high-performance concrete (UHPC)

The utilization of phosphorus slag (PHS) to replace the fly ash in the construction of hydraulic projects has attracted a growing attention in China. In this study, the influence of PHS fineness an...

https://www.worldscientific.com/doi/pdf/10.1142/S0218348X21400041

Effects of fineness and content of phosphorus slag on cement hydration, permeability, pore structure and fractal dimension of concrete

Comparison between the effects of phosphorous slag and fly ash on the C-S-H structure, long-term hydration heat and volume deformation of cement-based materials

A new hydration model of OPC [1, 2] was used in this study. The quantities of hydration products were calculated for saturated state hydration and for samples that have been dried to 11% rh after hydration. The chloride binding of several hydrated phases (C-S-H, monosulfate, hydroxy-AFm, AFt, CH, and Friedel's salt) has been studied and estimated in relation to the chloride content of the pore solution. Combining two new isotherms, for C-S-H and AFm chloride binding in hardened cement paste, and the computed quantities of all hydration products, a new formula for the chloride binding capacity of OPC pastes has been deduced. The new model is based on the chloride binding abilities of each hydrated phase, and therefore can distinguish between their contributions at different free chloride concentrations. When compared to experimental data, the results obtained using this new chloride binding isotherm have proven to accurately describe the chloride binding capacity of OPC pastes, results being within 12% of the experimental values for the whole range of free chloride concentrations considered, of up to 3 M.

Chloride binding related to hydration products part I : Ordinary Portland cement

Geopolymer is a new environment-friendly cementitious material, and the development of geopolymer can reduce the carbon dioxide emission caused by the development of cement industry. Geopolymer materials not only have excellent mechanical properties, but also have a series of excellent properties such as fire resistance and corrosion resistance. Most industrial solid waste and waste incineration bottom ash are piled up at will, which not only occupies land resources, but also has a bad impact on the environment. Recycling them can be used as raw materials for preparing geopolymers. Geopolymer materials can effectively adsorb heavy metals, dyes, and other radioactive pollution, which is very beneficial to society's future development. However, due to the excellent properties of geopolymer materials, its application goes beyond that. Some useful information about geopolymer materials was introduced in this paper. The paper included the geopolymerization, the source of raw materials, the types of activators, the preparation methods, and the different application fields of geopolymer materials. The factors affecting the fresh properties and mechanical properties of geopolymer materials were discussed. In this paper, the shortcomings and application limitations of geopolymer materials were summarized, and their progress was summarized to lay a theoretical foundation for the long-term development of geopolymer materials.

Advances in geopolymer materials: A comprehensive review

Low carbon design of an Ultra-High Performance Concrete (UHPC) incorporating phosphorous slag

In this paper, a type of typical locally available manufactured sand (MS) was utilized, and its effect on the properties of Ultra-High Performance Concrete (UHPC) were studied, based on physical and chemical points of views. According to the modified Andreasen and Andresen [1] (MAA) model, the natural river sand (RS) were partially replaced by manufactured sand to design UHPC. Then, the properties of the developed UHPC were evaluated. The obtained experimental results shown that the addition of angular MS can disturb the particle packing skeleton of UHPC. Moreover, the flowability and volume stability of the developed UHPC can also be negatively affected by the inclusion of MS. Especially the UHPC autogenous shrinkage, which could be even increased by 39.2%, when 50% of RS was replaced by MS. Additionally, based on the chemical reaction and microstructure development points of view, the use of MS at replacement levels up to 50% has limited influence on the hydration process and pore size distribution of UHPC, while the micro-hardness and SEM measurements showed that the connection of cementitious matrix with MS was more compact than that with RS, which should be attributed to the typical surface characteristics of the utilized MS particles.

Xu Gao

Papers

Low carbon design of an Ultra-High Performance Concrete (UHPC) incorporating phosphorous slag

The physical and chemical impact of manufactured sand as a partial replacement material in Ultra-High Performance Concrete (UHPC)

Utilizing coral waste and metakaolin to produce eco-friendly marine mortar: Hydration, mechanical properties and durability

Environmental and economical friendly ultra-high performance-concrete incorporating appropriate quarry-stone powders

Possibility and advantages of producing an ultra-high performance concrete (UHPC) with ultra-low cement content