Advanced Materials Research Vols. 753-755

Abstract: Using iron tailings from northern Tangshan region of China as the main material, fly ash and clay as the accessories, fired bricks were prepared. The influences of iron tailings content, heating rate, firing temperature and holding time on water absorption and compressive strength of bricks were investigated. the phases of fired bricks was characterized by XRD. The most suitable conditions is as follows: the range of the iron tailings content is 80%~ 95%, no more than 8°C/min has little effect on the properties of fired bricks, the range of feasible calcined temperature could be adjusted in 1020 ~ 1050°C for 1.5~2h, which make the physical properties and durability of fired bricks accorded with Chinese Fired Common Bricks Standard (GB/T5101-2003). The main mineral phases mainly constituted the mechanical strength of fired product are hematite, quartz, anorthite and augite.

Abstract: Rutting test, residual stability test and freeze-thaw split test were used to measure the properties of asphalt mixture with different graduation and same mixing amount of fibers, the results were analyzed to obtain the influence of graduation types in the road performance of fiber-reinforced asphalt mixture. The results showed as follows: fibers could obvious improve the high temperature property and water stability of asphalt mixture; the graduation types have visible impact on the improvement of all properties of fibers-reinforced asphalt mixture; SMA-13 has the greatest influence in improving the performance of fibers-reinforced mixture; the improving effect of dense graduation AC mixture will gradually decrease when the nominal maximum aggregate size was becoming bigger; graduation optimization design should be used in mix design of fibers-reinforced mixture to enhance its road performance.

Abstract: A new kind of concrete was made by the combination of corn stalks which is the main crop in northern China,natural pumice resources and cement. The results show that wrapped cover pretreatment technology can not only greatly reduce the water absorption of pumice and stalks, but also effectively plug up sugars in the corn stalks,which is advantageous to the formation of hardened concrete. The incorporation of the stalks can reduce the apparent density and thermal conductivity of the concrete. The composite concrete characterized by energy-saving and environment protection is worth popularizing.

Abstract: Solid recycled coarse aggregate concrete bricks were produced by QTY4-40 brick machine with strength grades of MU15-MU30. Recycled aggregate replacement rate was up to 100%. Water absorption and moisture content were tested. Two methods were taken to test the drying shrinkage. The impact of recycled aggregate replacement rate and curing period on the drying shrinkage rate, water absorption, moisture content, density was analyzed, and the relationship between them was presented. The results indicate that recycled aggregate can increase the shrinkage of solid concrete brick. The shrinkage of recycled solid concrete bricks' (fully substitute) is larger than ordinary concrete bricks' by 1.6-2 times. Water reducer is helpful to improve the water retention and decrease the shrinkage of brick. One of the test results of shrinkage got by the methods recommended in relevant specification is smaller.

Abstract: In the paper, a set of analysis formulas of pile-group of variable stiffness composite foundations was derived.The reasonability and reliability of the proposed method were showed by the results of a large scale model experiment.It is valuable to the analysis of the pile-group of composite settlement, the design optimization and the study of mechanism of pile-to-pile interaction.

Abstract: Reinforced concrete structures have been increasingly widely used in numerous industrial fields. These structures are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain, and the seashore. Thus, corrosion problems of the steel bars embedded in concrete are very important from a safety and economic point of view. In this study, the effects of cover thickness on the corrosion properties of reinforced steel bar embedded in mortar specimen were investigated using electrochemical methods such as corrosion potentials, polarization curves, cyclic voltammograms, galvanostat and potentiostat. Corrosion potentials shifted in the noble direction, and the value of AC impedance also exhibited a higher value with decreasing cover thickness, furthermore, polarization resistance also increased with decreasing cover thickness. This is probably that the thinner cover thickness, it is easy for the dissolved oxygen and chloride ion to intrude and diffuse to the steel bar, thereby making it easier to corrode on the steel surface compared to thicker cover thickness, which is resulted in forming the corrosive products on the steel surface. Therefore, it is considered that the corrosive products plays a role to provide nobler value of corrosion potential and higher value of impedance. Consequently, it seems that the corrosion resistance of inner steel bar may depend on mainly not cover thickness but the resistance polarization due to corrosive products in the case of immerged for 5 years in this experiment.

Abstract: In this study, it was aimed to research and interpretation of interaction mechanism of stabilizer low-molecular organic complexes with phyllosilicates mineral ingredients of loamy soils. Model adsorbents were investigation by using infrared spectroscopy method. Cation capacity is proposed as the express-evaluation integral characteristic to find out efficiency level structuring of stabilized soil. Prognostic scheme at the usage of the ionic binders for stabilized a road soils with different petrofabric structure is developed. The results of this investigation can be used as a basis for creation of road-construction material with high-performance characteristics.

Abstract: It is mainly addressed the rare necessary components in the Zijin Stone, and its anion releasing phenomenon, using X-rayfluorescence spectrometer to analysis the composition of elements, and using the DLY-6A232, one large gas ion test to identify the mount of the anion released.Many kinds of trace elements containing in the stone necessary for human, such as KCaAlFeTiVCrSrCuMgMnZn, and the mount of anion released as much as 1409 ion/cm^-3 both are important and vital factors to benefits our health.

Abstract: The hydraulic permeability performance of geosynthetics is an important functional technical index in the field of engineering application. In this paper, the pore size characteristics of a series different specifications of spunbond and needlepunched nonwoven geotextile has tested through capillary flow aperture measuring instrument, including average pore diameter, maximum pore size and pore size distribution. The permeability characteristics of nonwoven geotextile has measured by vertical permeability measuring instrument, including flow index and vertical permeability coefficient. We study on the compressive properties of nonwoven geotextile under the different pressure, through the relationship between the average pore diameter and flow index to fit curve, and built the regression equation, so we can calculate and predict the water permeability performance through pore size Characteristics.

Abstract: In this study corn husk used as raw material, and achieved corn husk fiber through degumming properly. Then degradable fiberboard can be obtained with husk fiber and polylactic acid particles through blending and hot pressing. Taking mass fraction and length of corn husk fiber, hot-pressing time and temperature as factors, and taking tensile, bending and impact strength as index, through the L₉ (3⁴) orthogonal testing and range analyzing and achieved the optimal process parameters is: corn husk fiber mass fraction is 50%, corn husk fiber length is 10 mm, hot pressing time is 6 min, hot pressing temperature is 180 °C. Under the optimal process condition, a optimal fiberboard is obtained, whose tensile strength is 69.32 MPa, bending strength is 90.26 MPa, impact strength is 18.5 KJ/m². The conclusion of this paper provides the theoretical guidance for the reuse technology of corn husk fiber.