Advanced Materials Research Vols. 535-537

Abstract: Reactive powder concrete (RPC) has a higher strengths, as well as excellent durability and corrosion resistance. So, it is expected to be increasingly used in marine engineering. In this study, After the RPC samples had been subjected to gradually increased high-pressure seawater for 30 days, the chloride contents in the samples along with the infiltration direction were calibrated on an energy dispersive spectrometer. On the basis of second Fick’s law, the chloride ion diffusion model and service life prediction model of reactive powder concrete in sea water are established. The service life of an actual reactive powder concrete structure could be predicted.

Abstract: The influence of air content on compressive strength of C20，C30，C40 and C50 concrete was investigated in this paper. The result shows that this relationship varied with concrete strength grade. For C20~C40 concrete, the air content increases with addition of air entraining agent, while a maximum air content value appears for C50 concrete. The compressive strength of C20 decrease slightly with the air content, on the other hand, that of C40 significantly decreases relatively.

Abstract: Longxihe dangerous rock is located on both sides of gully of Longxi river in Chongqing. The complex geological environmental condition made dangerous rock a typical geological hazard to Chongqing. Through field investigation of dangerous rock zone and analysis of geological environment condition, we researched the formation mechanism and unstable mode of dangerous rock and done qualitative analysis and analytical analysis to the dangerous rock. Under the condition of dead weight and surface load , the stability coefficient is 1.16~1.29, which illustrates that dangerous rock is basically stable; under the condition of dead weight, surface load and hydrostatic pressure, stability coefficient is 0.95~1.04, which illustrates that dangerous rock is not stable. The emergency capacity is so slow that it’s urgent to take treatment measures to control dangerous rock. And the control measures of clearing dangerous rocks, bolting, concrete spray protection and local hanging net to support should be adopted immediately.

Abstract: In this research, based on neural network, thirty typical moraine-dammed lakes were selected as the training set. In accordance with the rules defined, ten evaluation indexes were made dimensionless and used to train the model. Then the research could get the applicable model that evaluated the probabilities of moraine-dammed lake outburst in the Himalayas region of Tibet, China. Then the probability of outburst was predicted for the Laqu Lake based on the developed model, and the predictive value was 0.538. In terms of risk level standards divided, the Laqu Lake was high-risk, which is consistent with the field survey. It well demonstrated the applicability that using the neural network to assess the probabilities of moraine-dammed lake outburst.

Abstract: An experimental study was carried out to examine the non-uniform corrosion of plain steel bars in reinforced concrete beams partially placed in 5% sodium chloride solution under conditions of accelerated corrosion. 4 reinforced concrete beams with different concrete strength were made. The crack distributions of the beams due to pre-loads and expansion of corrosion product, and the sectional corrosion characteristics of plain steel bars are described in detail. The sectional area loss relating to mass loss and change along pure bending length of the beams are discussed. These can be used as the basis of test for further studies to build the numerical models of serviceability of corroded reinforced concrete beams.

Abstract: The compacting curves of mud solidified by some curing agents, including cements, HSC301, CVC and CDK, were studied by heavy compaction tests. Based on this, prediction formulas for optimum water content and maximum dry density of solidified mud were regressed. Experimental results showed that the optimum water content of mud was increased and the maximum dry density reduced with the increasing amount of curing agent. Regression formulas were offered as a basis for the selection of mud curing agents.

Abstract: The purpose of the present paper is to show that the problem of geometrically non linear steady state periodic forced response of symmetrically and asymmetrically laminated composite beams with immovable ends can be reduced to that of isotropic homogeneous beams with effective bending stiffness and axial stiffness parameters. This simple formulation is developed using the governing axial equilibrium equation of the beam in which the axial inertia and damping are ignored. The theoretical model is based on Hamilton’s principle and spectral analysis, to determine the effect of the excitation frequency and level of the applied harmonic force on its dynamic response at large vibration amplitudes, which are found to be in a good agreement with the published results.

Abstract: In present work the paths for obtaining the road oil bitumen are presented from the wastes of coal oil of the Karazhyra field. For the improvement of the quality of obtained bitumen the modification was carried out of elementary sulfur. The processes of modification by elementary sulfur allow to obtain the viscous road oil bitumen of high quality.

Abstract: It’s a chemical method that adding TOR into asphalt rubber to be TOR asphalt rubber mixture. In this study, 70# basic asphalt from Nanjing Jinling Company and 60 mesh waste rubber powder from Jiangyan Honglei Company were chosen for the SMA13 grading and SUP13 grading by the best preparation technology. The high temperature stability, anti-cracking performance and water stability of TOR asphalt rubber mixture were studied and the influence of dry and wet molding process on road performance of TOR asphalt rubber mixture was compared. The results show that both the dynamic stability and the low-temperature cracking performance of wet forming specimens are better than the dry process. The water stability of wet molding process is also slightly better than the dry process. And expansion rate tests were carried out on asphalt mixtures prepared by dry and wet forming processes on continuous gradation and discontinuous gradation to validate the applicability of discontinuous gradation to asphalt rubber.

Abstract: This paper reviews the state-of-art of researches on the carbonization of concrete. The influencing factors are concluded as two aspects as the internal concrete and the external environment and service conditions. The main internal factors include the cement and admixtures, the water to cement ratio, the concrete strength and others such as the type, grading and size of aggregate and the additives. The main external factors include the concentration and pressure of carbon dioxide, the temperature and relative humidity of environment, the curing and service conditions and the loading states. The typical forecast models of carbonized depth of concrete based on the fundamental reaction engineering principles, the lab experimental results and the practical engineering investigations are summarized for the reference of further study.