Bacteria-based self-healing concrete is a construction material used to repair cracks in concrete, in which the bacterial spores are immobilized by bacteria carriers. However, the currently available bacteria carriers are not always suitable due to a complicated procedure or high cost. To develop a more suitable bacteria carrier as well as improve the anti-crack capability of self-healing concrete, in this study we evaluate the feasibility of using rubber particles as a novel bacteria carrier in self-healing concrete. Two types of self-healing concrete are prepared with rubber particles of different sizes to quantify the crack-healing effect. In addition, the fluidity and mechanical properties of the self-healing rubber concrete are compared with those of plain concrete and normal rubber concrete. The experimental results show that the self-healing rubber concrete with a particle size of 1~3 mm has a better healing capacity than the self-healing rubber concrete with a particle size of 0.2~0.4 mm, and the width value of the completely healed crack is 0.86 mm. The self-healing rubber concrete has a higher slump than the plain concrete and normal rubber concrete. According to the strength tests, the compressive strengths of the self-healing rubber concrete are low early on but they exceed those of the corresponding normal rubber concrete at 28 days. Moreover, the self-healing rubber concrete has higher splitting tensile strengths than the plain concrete and a better anti-crack capability. The results of a comparison to the other two representative bacterial carriers indicate that rubber particles have potential to be a widely used bacteria carrier for practical engineering applications in self-healing concrete.

Preloaded foundation capacity has recently been a topic of major interest in offshore foundation engineering. The increase in undrained shear strength due to preloading and consolidation enables the foundation to resist a larger environmental load, thereby reducing the size of the footprint. This paper investigates the shape and size of the VHM (i.e., vertical, horizontal, and moment) capacity surface of a skirted circular foundation by comparing both the no-preload and the post-preload responses using coupled small strain finite-element analyses. The influence of the distribution of in situ undrained shear strength, the magnitude of vertical preload, and the duration of consolidation on the foundation’s combined capacity are considered. An approach to estimating the post-preload VHM capacity surface of the skirted circular foundation is provided using a new set of formulations that are compared with available solutions for other foundation geometries and soil conditions.