Yes / Traditional concrete fulfills the mechanical requirements for marine infrastructures but lacks durability. This study employed nano-engineering techniques to address the durability challenges in marine concrete infrastructures by enhancing the chloride ions penetration resistance of low- and medium-strength concrete to be comparable to that of high-strength concrete without increasing cement dosage. Meanwhile, nano-engineered concrete is also expected to reduce the cost and CO2 emissions of concrete structures over the life cycle. For this purpose, the effect and mechanisms of nanofillers on the durability and microstructures of concrete were investigated. Moreover, CO2 emission, cost, and sustainability of nano-engineered concrete were evaluated. The results indicated that a small content of nanofillers remarkably inhibited the penetration of chloride ions into concrete, without increasing cement content. The chloride ions diffusion coefficient of concrete with nanofillers is as low as 3.9010-12 m/s, representing a reduction of 62.8% compared to blank concrete. Moreover, nanofillers effectively refine the concrete microstructure by inducing hydration products into short rods, blocks, and lamellae. The thickness of the interfacial transition zones (ITZs) between cement mortar and gravel as well as cement paste and river sand decreases by 40.7%-55.9%/36.1%-47.4%, respectively, while the porosity of ITZs decreases by 8.7%-17.8%, after adding nanofillers. In addition, the cost and CO2 emission of nano-engineered concrete during production are reduced by 18.1%-27.8% and 14.4%-22.2%, respectively, compared to traditional concrete. These findings demonstrate that nano-engineered concrete can serve as a viable construction material with reasonable strength, high durability, low carbon footprint, and low cost for marine concrete infrastructures. / National Science Foundation of China (52308236, 52308243 and 52368031), Natural Science Joint Foundation of Liaoning Province (2023-BSBA-077), (LH2023E069), and the Major Science and Technology Research Project of the China Building Materials Federation (2023JBGS10-02). / The full-text of this article will be released for public view at the end of the publisher embargo on 04 Dec 2026.

Yes / This paper investigated the bond characteristics between eight types of nanofillers modified reactive powder concrete (RPC) and plain steel bars, aiming to explore the modifying mechanisms and establish a bond-slip relationship model for nanofillers modified RPC and steel bar interface. The experimental results indicated that the incorporation of nanofillers can increase the bond strength and reduce the slip between RPC and plain steel bars. It was shown that a 2.15 MPa/20.5% of absolute/relative increase in cracking bond strength, a 1.25 MPa/10.3% of absolute/relative increase in ultimate bond strength, a 2.35 MPa/22.4% of absolute/relative increase in residual bond strength, a 0.592 mm/56.5% of absolute/relative reduction in ultimate bond slip, and a 1.779 mm/52.1% of absolute/relative reduction in residual bond slip were the best achieved due to the addition of various nanofillers. The enhancement of nanofillers on RPC-steel bar interface has been mainly attributed to RPC microstructure improvement, optimization of intrinsic compositions, and elimination of defects in the interface, especially the underside near steel bar, due to the nano-core effect of nanofillers enriched in the interface. In addition, the bond-slip relationship of nanofillers modified RPC-steel bar interface can be accurately described by the proposed model considering an initial branch. / The authors would like to thank the funding offered by the National Science Foundation of China (51978127 and 51908103), and the Fundamental Research Funds for the Central Universities (DUT21RC(3)039).