Three-dimensional (3-D) printed concrete is a new technology for civil engineering. In this paper, 3-D printed concrete was prepared for a study on static and dynamic properties. The best fluidity of the concrete was researched and the optimization mixture ratio for better mechanical performance was discussed. The mechanical performances of the concrete were tested and the anisotropy phenomenon in 3-D printed concrete was found. The computed tomography (CT) scanning and imaging progress methods were used to discuss the reason for the phenomenon. The penetration experiments were carried out to research the dynamic performance of the 3-D printed concrete. The results of the penetration tests were compared with the empirical formulas. The Young formula was improved according to the results.

The light-transmitting cementitious materials (LTCM) in a homemade device were produced with plastic fiber-optics, luminescent powder, reflective powder, and cement. The mechanical strength of LTCM was greatly enhanced by the incorporation of optical fiber, luminescent powder, and reflective powder. The maximum increase of the 3-day, 7-day, and 28-day compressive strengths and 3-day flexural strength of the LTCM are 15.33, 19.05, 13.10, and 5.15 MPa, respectively. The optical test results show that the absorption rate increases slowly with the increasing wavelength in the visible light range, and the 7 × 7 fiber arrangement mode obtains the best average absorption rate up to 0.58%. The reflectivity rate reached the peak values of 40.9, 37.2, and 29.2% in the range of the green light wavelength with 5 × 5, 6 × 6, and 7 × 7 of the fiber meshes. The transmittance rate of concrete with 5 × 5, 6 × 6, and 7 × 7 jumps to 0.28, 0.82, and 2.0% at the wavelength of 400 nm and then remains stable with the increase of the wavelength.

In the study presented in this paper, the quasi-static compressive behaviors of coral aggregate concrete (CAC) were further investigated using the mesoscale modeling method. Three-dimensional (3-D) random particle mesoscale models for CAC with different concrete strength grades were developed and validated through the comparison of numerical and test results. The effect of strength grade on the failure pattern and failure process of CAC subjected to uniaxial compression was numerically studied. The numerical stress-strain curves of CAC obtained by the mesoscale approach were compared with corresponding test results. The results indicate that CAC with a higher strength grade would show obvious brittle failure and the failure surface in concrete would penetrate through coral aggregate. The visible failure formation of CAC is the result of internal microcracks propagating from coral aggregate to the interfacial transition zone (ITZ)/mortar matrix and connecting with each other until main cracks generate in the concrete. Based on the regression analysis of test and numerical data, a new constitutive model for CAC was proposed and verified, which is of great significance for the structure design and performance analysis of CAC engineering. Furthermore, the mesoscale modeling approach has been confirmed for the property prediction of CAC and is expected to be applied further in the field of engineering design.

Wet-mix shotcrete has been used more and more for structural applications in the past few decades. Recently, wet-mix shotcrete was successfully used to construct a mass structural wall with congested reinforcement and minimum dimensions of 1.0 m in a sewage treatment plant. A low-heat shotcrete mixture that included up to 40% slag was proposed for shotcrete application. A preconstruction mockup was shot to established proper work procedures for shotcrete application and qualify the shotcrete mixture and shotcrete nozzlemen. Extraction of cores and cut windows from the mockup confirmed proper consolidation around the congested reinforcement. A thermal control plan was developed, which included laboratory and field testing requirements, thermal analysis modeling with a three-dimensional (3-D) finite element program, and thermal control requirements, including installation of cooling pipes and thermal blankets. Shotcrete proved to be an efficient means for mass concrete structural construction. Thermal control for mass shotcrete construction was studied, and the proposed thermal control plan was proved to function properly. The general guidance for mass shotcrete construction is provided.

Unlike traditional experimental testing, some procedures have been developed for the characterization of microstructures of cement-based materials. Based on the microstructure of the cement hydration model obtained from a digital image-based model, the parameters of pore structure were in-place continuously determined by CEMHYD3D. The characteristic parameters of pore include total porosity, the continuous pore, isolated pore, dead-end pore, connectivity, pore size distribution, specific surface area, and tortuosity. According to the combustion algorithm, the three-dimensional (3-D) voxel-erosion method, the mercury intrusion porosimetry simulation, the continuous PSD algorithm, and the random walk algorithm, the physical models are developed into program to obtain the characteristic parameters of pore structure evolution. The results show that the dead-end pores and the isolated pores begin to decrease after the continuous pores disappear. The pore size distribution of the pore structure is calculated with finer resolution. The water-cement ratio (w/c) and hydration degree have a significant effect on the specific surface area of the pores. With the increase of the degree of hydration, the tortuosity of the pore structure increases gradually. Finally, the simulation results are compared to the experimental values and the literature data that have a good agreement.