Advanced Materials Research Vols. 838-841

Abstract: The finite element software ANSYS/CivilFEM was applied to analyses the influence of steel bar restraint on creep and shrinkage of reinforced concrete. The analysis results are in good agreement with the experiment results. When the reinforcement ratio is low, the steel bar exerts less influence on creep and shrinkage, and the influence of steel bar can be neglected in engineering application. However, the reinforcement can effectively reduce creep and shrinkage development when the reinforcement ratio is high.

Abstract: The primary objective of this paper was to study the mechanical properties and durability of the cement stabilized gravel which added rubber particles by using macroscopic and microscopic test. Through tests of compression, splitting and frost resistance, relationships between mechanical properties of samples and rubber particles content were studied. Scanning electron microscope (SEM) was applied to analyze the micro-morphology and elemental composition of samples, X-ray diffraction (XRD) was engaged to identify the product phases. The tests results showed that compressive strength of mixtures decreased with the rubber particles content increasing and the early strength effect was obvious, splitting strength decreased slightly. It also indicated that the addition of rubber particles can improve the frost resistance of the mixtures. As a result, the frozen stability coefficient (K) of samples was improved from 0.89 to 0.97. XRD and SEM analyses showed that calcium silicate hydrate (CSH) was resultant and the interface bonding between sand and CSH was better than rubber particles and CSH, which the latter had interface cracks.

Abstract: Based on a wind turbine thick concrete raft foundation for the engineering background, through the adiabatic temperature rise test, the datum of the hydration heat of concrete are obtained; and concrete solidification temperature field numerical simulation and analysis are conducted by finite element analysis software ANSYS; by means of the temperature sensor measurement systems, the foundation concrete pouring process variation of the temperature field is obtained by real-time monitoring. Studies show that: the temperature rise inside the concrete points has the same trend, but the peak and the peak of the age are different. The maximum temperature inside the concrete is mostly shown in the initial 3-5d of concreting; temperature gradient along the thickness direction of the foundation is obvious; massive concrete is significantly affected by the outside temperature.

Abstract: Aim to produce metal strips in millimeter scale, the Top Side-pouring Single Roll Casting process and the Top Side-pouring Twin Roll Casting process were investigated in this paper, using commercially pure lead and commercial-purity aluminum as the experimental materials. Numerical simulation was conducted before the experiment. The results show that, the Top Side-pouring Single Roll Casting process and the Top Side-pouring Twin Roll Casting process can both realize the uniform flow distribution and rapid solidification, but the surface of the strips cast by the former are irregularity because of free solidification, while that from the latter present a state of rolling. And one can change the gauge of nozzle and the speed of cooling roll, to regulate the thickness of thin strips, and by changing the shape of the nozzle, the thickness distribution can be handled.

Abstract: This study focused on the performance of the Large Stone Permeable Asphalt Mixture (LSPM) with neat asphalt and its feasibility to use as asphalt pavement flexible base. For comparision, LSPM mixtures were designed respectively with neat 60/70-grade asphalt and modified asphalt and the performance of LSPM was studied and compared by volume index test, draindown test, Hamburg Wheel-tracking Test and dynamic modulus test. The results showed that the performance of LSPM with modified asphalt was superior to LSPM with neat asphalt and cellulose fiber, but draindown and rutting performance of LSPM with neat asphalt met requirements of corresponding specification and dynamic modulus of LSPM with neat asphalt had the same characteristic with LSPM with modified asphalt, which proven that LSPM with neat asphalt can use as asphalt pavement flexible base by properly mix design and pavement structure design.

Abstract: Several typical soil samples in Shanxi Province were selected. Laboratory experiments were adopted to study the CBR of the three kinds of soil samples with different compaction and different water content. Orthogonal experiment was used to analyze the impact of factors including water content, compaction and soil sample category on the CBR value. The result shows that the moisture content has great impact on CBR value and the CBR value is maximize under optimum moisture content and maximum degree of compaction condition, while the not flooded CBR is decrease with the increasing of water content.

Abstract: A nanoceramic composite is proposed to coat steel rebar used in reinforced concrete with the purpose of protecting it from corroding. This is a new material in the civil engineering field. For this reason several tests have been performed over coated steel rebar with the nanoceramic composite in order to know its viability and its properties. A bending test showed that the coating is stiff, and therefore not flexible enough to bend it as a stirrup. For this reason if a bended rebar were needed, it should be bent before coating it. While the pull-out test concluded, there is no significant loss of bond strength due to the contact of the coating with the concrete. The chemical test indicated that the coating cannot bear strong alkali and acid environments, but resisted without problems under saline environments with neutral pH. Finally a cathodic disbondment test and a corrosion test were performed. These tests showed problems with the coating process because the behavior of during the execution of the test differed from the expected.

Abstract: Mixed paraffins, which had low phase transition temperature and high enthalpy,were used as phase change material (PCM),light-weight clay ceramsite was used as carrier, paraffin/ceramsite PCM was prepared and which was encapsulated by epoxy resin and triethylenetetramine.The results show that the proportion of liquid paraffin to solid paraffin is 4:6 through both temperature-time curve test and DSC analysis.The quality of paraffin which is absorbed in vacuum condition for 2 hours is 95.5% and the minimum leakage quality of paraffin in the process of thermal cycling is 3.3% which is half of the unencapsulated.It takes 480min for paraffin ceramsite PCM drop its temperature from 24°C to 18°C,and it is 240min for normal concrete which could effectly prevent heat transfer inside and outside,then reduce the indoor temperature fluctuations and improve living comfort compared to ordinary concrete.

Abstract: Combining the South-to-North Water Diversion Middle Route Project, the effect of cellulose fiber on the mechanical property, ultimate tensile value, compressive elasticity modulus, durability and crack resistance property of high performance concrete was studied. The test results show that mixing with the cellulose fiber in concrete has less effect on the compressive strength, but can improve the splitting tensile strength, the axial tensile strength and ultimate tensile value of concrete, extend the cracking time of concrete, reduce the crack width and the cracking area of concrete and improve the crack resistance of concrete.

Abstract: Rock-socket cast-in-situ piles is a commonly used style of foundation, but theoretical analysis, experiments and test research of bearing capacity behavior about rock-socket piles in soft rock have not adapted to the requirement of engineering. The static loading test of single pile on a project in argillaceous and silt laminate, through which the skin friction and point bearing capacity were measured, the bearing capacity behavior of rock-socket cast-in-situ piles in soft rock was analyzed.