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Nanoscale impact can bring big changes in micro-meso-macroscale behaviors of the composites. addition of nano fillers makes cementitious materials stronger, more durable and multifunctional/smart. This paper aims at investigating the underlying mechanism for understanding and controlling the nano-engineered cementitious composites. The nano-core effect is proposed through integrating core-effect with nano effect, and is proved by experimental evidences for the cementitious composites with different nano fillers. The nano-core effect is closely relative to the intrinsic properties of nano fillers, composition and processing of the cementitious composites. The behaviors of the nano-engineered cementitious composites are governed by nano-core effect zone, i.e. nano-core-shell element. It is therefore concluded that the nano-core effect is fundamental for design, fabrication and application of the nano-engineered cementitious composites.

Nanographite platelets (NGPs) are used as multi-functional fillers to develop cementitious composites because the unique carbon-carbon hexagonal plane structure makes NGPs have excellent mechanical, electrical, dielectric and thermal properties. In this paper, cementitious composites filled with NGPs are fabricated to investigate the effect of NGPs on mechanical, thermal and electromagnetic properties of cementitious composites. Experiment results show that the addition of NGPs can effectively modify the above-mentioned properties of cementitious composites. When the content of NGPs reaches 5%, the hardness of the composites increases 1.5-fold, the abrasive loss per unit area of the composites reduces by 71%, the abrasion depth of the composites reduces by 73%, the thermal conductivity of the composites increases by 77%, the specific heat of the composites decreases by 17.7%, the damping ratio of the composites increases by 20%, and the electromagnetic wave reflectivity of the composites decreases by 38% compared with pure cementitious composites.

The mechanical and electrical properties of reactive powder concrete (RPC) with nano-ZrO 2 (NZ) are investigated in this research. The reinforcing mechanisms of NZ to RPC are studied through thermogravimetry (TG) analysis, scanning electron microscope (SEM) observation and X-Ray powder diffraction (XRD) analysis. Research results indicate that the NZ has obvious modifying effect to RPC. The flexural, compressive and splitting strengths of RPC with NZ at curing age of 28 days achieve increases of 36.6%/4.19 MPa, 16.3%/16.18 MPa and 34.0%/1.08 MPa, respectively, compared to plain RPC. The addition of NZ makes a 20% decrease in the electrical conductivity of RPC. The NZ does not accelerate the hydration process of RPC. However, the microstructures of NZ filled RPC are denser than that of plain RPC. This leads to the reduction of the growth space of calcium hydroxide (CH) crystals, thus the size of CH crystals is reduced. Furthermore, NZ can reduce CH crystal orientation to improve the microstructures of the composites.

This article simulates the stress state and strain compatibility of the sensor embedded into concrete member to provide theoretical support for design and application of cement-based sensor. The effect of sensor dimension, voltage electrode separation, and surface roughness on strain compatibility between the embedded sensor and the concrete surrounding it is analyzed. The optimally designed sensor is embedded into concrete for health monitoring, and its stress state is investigated. A modified method for the monitoring results is proposed by studying the effect of embedded location and small deflection angle of the sensor, strength grade of concrete, amplitudes, and types of load on stress/strain compatibility. The results show that the optimum dimension and voltage electrode separation of the sensor are 20 mm × 20 mm × 40 mm and 10 mm, respectively. The sensors are nearly subjected to a uniaxial stress state when the sensor is embedded in internal strain-homogeneous area of concrete structure. The presence of the sensor will affect the stress distribution of the concrete around the sensor. The strain of the sensor is approximately coordinated with that of concrete surrounding it. The monitoring results need to be modified with the correction coefficient of corresponding effect factors to ensure monitoring accuracy.