This paper presents the experimental findings of a study on the influence of combining usage of supplementary cementitious materials (SCMs) on the performance of high-strength concrete (HSC) subjected to elevated temperatures. In this study, four types of HSC formulations were prepared: HSC made from cement and fly ash (FA), HSC made from cement and ultra-fine fly ash (UFFA), HSC made from cement and UFFA-metakaolin (MK), and HSC made from cement and FA-UFFA-MK. Mechanical and physical properties of HSC subjected to high temperatures (400, 600, 800, and 1000 °C) were studied. Furthermore, the relation between residual compressive strength and physical properties (loss mass, water absorption, and porosity) of HSC was developed. Results showed that the combined usage of SCMs had limited influence on the early-age strength of HSC, while the 28-d strength had been significantly affected. At 1000 °C, the residual compressive strength retained 18.7 MPa and 23.9 MPa for concretes containing 30% UFFA-5% MK and 10% FA-20% UFFA-5% MK, respectively. The specimen containing FA-UFFA-MK showed the best physical properties when the temperature raised above 600 °C. Combined usage of SCMs (10% FA-20% UFFA-5% MK) showed the lowest mass loss (9.2%), water absorption (10.9%) and porosity (28.6%) at 1000 °C. There was a strongly correlated relation between residual strength and physical properties of HSC exposed to elevated temperatures.

This study proposes a new cement mortar incorporating damping aggregate (DA) and investigates the mechanical properties and damping property of the cement mortar. Four types of DA were prepared, lightweight aggregate presaturated water and three types of polymer emulsion. Further, the effects of polypropylene fiber and rubber powder on the performance of the cement mortar were studied. The experimental results showed that the damping ratio of specimens containing 70% DA was approximately three times higher than that of the reference mortar, with a slight decrease in the mechanical properties. Adding fiber was more effective than rubber powder in improving the damping ratio of the cement mortar, and the optimal dosage of fiber was 0.5%.

In this paper, a shell structure ceramsite has been prepared and researched in order to attempt a new method of producing lightweight ceramsite. In the experiment, raw material was made into slurry and polypropylene balls were treated with the soak-and-pick process in the slurry to make the green body; later, the green body was dried and fired in the furnace to make the shell structure ceramsite. The result showed that the shell structure ceramsite has an appropriate cylindrical compressive strength (0.87 MPa) with a bulk density at a low level (0.375 × 103 kg/m³), which can be used for lightweight concrete preparation, and with its special structure, it can be used for many other purposes.

Sintering solidification is an effective way to treat soil contaminated with nonvolatile heavy metal. The ceramsite prepared from contaminated soil after sintering can be used as lightweight aggregate in concrete. The preparation process of ceramsite can be divided into two steps: granulation and sintering. As one of the key processes, granulation is directly related to the final solidification and physical properties of ceramsite, and the properties of the clay are directly related to the granulation process. In this work, clays from different regions granulated with disc granulation were studied and compared. The results showed that different clays had significantly different performances in granulation with the same granulation system, and each clay had its own best process parameter. The significance analysis showed that the volume surface mean diameter and the reduction ratio had the most significant impact on the granulated fraction among all the factors. No matter which process parameter was used, as the particle size increased, the granulated fraction increased first and then decreased, and the best results were obtained when the average volume diameter was about 20.5 µm. Furthermore, as the reduction ratio increased, the granulated fraction decreased. These two factors are easy to measure and can be used for predicting the granulation effect of different clays, which can further guide industrial production.