Experimental Study on the Influence of Curing Conditions on Capillary Absorption of Concrete

Both the hardening process and formation of microstructure of concrete are significantly influenced by the curing condition. The capillary absorption of concrete is closely related to the structure and distribution of the pores within the material. This paper presents an experimental study on the influence of four curing conditions, i.e., standard curing, natural curing, water curing, and sealed curing, on the capillary absorption of normal concrete. Compressive strength tests on the cylinder specimens that are core drilled from concrete slabs are carried out. The “pie” samples cut from three different locations along the height direction of cylinder specimens are then conducted to measure the ultrasonic pulse velocity (UPV) and porosity, which quantitatively characterize the internal state of concrete after 28 days initial curing. In order to realize the continuous observation of water absorption testing, an improved gravimetrical test setup for measuring the sorptivity (the rate of water absorption) of concrete is designed to investigate capillary absorption of the “pie” samples. The experimental results indicate that the curing condition has an important influence on compressive strength, ultrasonic pulse velocity, and porosity of concrete. The temperature and relative humidity are the key factors to ensure strength development during the curing procedure and to determine the internal pore structure and the compactness of concrete. For the same curing conditions, the cumulative water content, sorptivity, and porosity of concrete gradually decrease with the increase of distance from the surface, but the ultrasonic pulse velocity reverses

Optimal View Angle in Collective Dynamics of Self-propelled Agents

We study a system of self-propelled agents in which each agent has a part of omnidirectional or panoramic view of its sensor disc, the field of vision of the agent in this case is only a sector of a disc bounded by two radii and the included arc. The inclination of these two radii is characterized as the view angle. Contrary to our intuition, we find that, the non-omnidirectional-view for swarm agents with periodic boundary conditions in noiseless Vicsek model can accelerate the transient process of the emergence of the ordered state. One consequent implication is that, there are generally superfluous communications in the Vicsek Model, which may even obstruct the possible fast swarm emergence. This phenomenon may invoke further efforts and attentions to explore the underlying mechanism of the emergence in self-propelled agents.Comment: 4 pages, 6 figure

Experimental Study on the Feasibility of Using Water Glass and Aluminum Sulfate to Treat Complications in High Liquid Limit Soil Subgrade

The feasibility of using water glass and aluminum sulfate to treat high liquid limit soil subgrade diseases is studied through laboratory experiments, and the following results were observed. After improving the high liquid limit clay with water glass and aluminum sulfate, the liquid limit decreases, the plastic limit increases, and the plasticity index decreases. Compared with untreated soil, the clay content of the improved soil decreases, while the silt and coarse contents increase. The absolute and relative expansion rates of the improved soil are both lower than those of the untreated soil. With the same number of dry and wet cycles, the decreased degrees of cohesion and internal friction angle of the improved soil are, respectively, one-half and one-third of those of the untreated soil. After three dry and wet cycles, the California bearing ratio (CBR) of the untreated soil does not meet the requirements of specifications. However, after being cured for seven days and being subjected to three dry and wet cycles, the CBR of the improved soil, with 4% water glass solution and 0.4% aluminum sulfate, meets the requirements of specifications

Noise in Genotype Selection Model

We study the steady state properties of a genotype selection model in presence of correlated Gaussian white noise. The effect of the noise on the genotype selection model is discussed. It is found that correlated noise can break the balance of gene selection and induce the phase transition which can makes us select one type gene haploid from a gene group.Comment: 8 pages, 4 figure