Applied Mechanics and Materials Vols. 584-586

Abstract: In order to solve the problems relevant to asphalt concrete,such as cracking in low temperature, bleeding in high temperature and water damage,this paper put forward the ideal incorporation of steel fiber with asphalt concrete to reinforce the pavement performance and service life.By analyzing the test results such as rutting test, low temperature bending test,freeze-thaw splitting test and comparing with the stability in high temperature, anti-cracking performance in low temperature and the water stability between steel fiber asphalt concrete and the ordinary asphalt concrete,we can conclude that adding steel fiber with asphalt concrete can significantly improve the performance of road.This paper has reference value for choosing asphalt pavement in areas of low temperature and heavy traffic.

Abstract: The BP neural network model for creep degree of concrete is established,in which concrete age under load and loading time as input variables and the creep degree of concrete as output variable. In order to get best optimal weight and threshold of the BP neural network, genetic algorithms method has been used by selection, crossover and mutation operation. The BP neural network model is applied to the engineering of “515”dam.Comparison the prediction results of the BP neural network and the eight-parameters formula of concrete creep degree, the BP neural network model has high prediction accuracy. What’s more, this intelligent prediction model for creep degree of concrete has good credibility and reference value in practical engineering.

Abstract: Experimental method is applied to analysis the mechanical properties of super early-strength composite fiber concrete on high temperature. Specimen are heated to in the stove at different temperatures for 30 Minutes, then the axial compressive strength can be measured. The experimental results showed that: the high temperature mechanical properties of materials decreased significantly; compared to ordinary concrete specimen, the mechanical properties of super early-strength composite fiber concrete decline slower.

Abstract: The mechanical tests of normal concrete (NC) specimens, steel fiber reinforced concrete (SFRC) specimens and polypropylene fiber reinforced concrete (PPFRC) specimens have been carried out. Fiber-reinforced concretes containing different volume fraction and aspect ratio of steel and polypropylene fibers were compared in terms of compressive, splitting tensile, ultimate tensile properties. Test results indicate that the mechanical properties of NC can be improved by addition of steel fibers and can be enhanced with the increase of fiber content. However, polypropylene fiber may cause opposite effect, if volume fraction too high.

Abstract: Considering the high absorption of water is a distinctive feature of recycled crushed bricks coarse aggregate, the mixture ratio text of recycled concrete using crushed bricks as coarse aggregate is carried out, and the compressive performance is studied.The resert indicate , the strength grade of recycled concrete which using bricks as coarse aggregate can reach C20 and C25, characterisitic value of cubic concrete compressive strength at the age of 28 days are 21.2MPa and 27.55MPa;Based on regression analysis of test data , the formulas which estimated the strength of recycled coarse aggregates concrete are given out. Calculated values are in agreement with the measurement values, which can provide a reference for engineering application.

Abstract: Through the ordinary Portland concrete mixed with slag powder and its experimental research, studies and analyzes the impact on the concrete splitting tensile strength of different age, slag powder content and the water-cement ratio. The test results show that the increase of slag powder content makes splitting tensile strength of concrete reduce after the first increase; growth age makes splitting tensile strength of concrete increases; increasing water-cement ratio makes the splitting tensile strength of concrete intensity decreases.

Abstract: Taking the limestone and siliceous rocks as coarse aggregates to mix concrete,through normal pressure steam curing and autoclave curing,the concrete compressive strength after demould and compressive strength after autoclave curing are tested.The results indicate that the concrete compressive strength increases obviously after normal pressure steam curing when taking the limestone and granite as coarse aggregates,and the strength increasing laws are basically in accordance.However,the concrete compressive strength is great different after autoclave curing when taking the limestone and granite as coarse aggregates,the concrete strength increases lower with limestone as coarse aggregate,but the concrete strength increases higher with siliceous rocks as coarse aggregate.

Abstract: In order to investigate the bond strength between deformed steel fiber and concrete, various deformed steel fibers, like arch type fiber, spiral type fiber, bundle fiber, end-hooked fiber and so on, are produced. Straight type fiber and deformed fiber were embedded in mortar to do the bond strength experiment. A comparison with each other was carried out. It has been found that the change of the fiber cross section increases the bond strength between steel fiber and concrete matrix, growth range outweighs 100%. When modified both ends of anchorages, the bond strength raises 400% in contrast with straight type steel fiber. Besides, the deformed fiber, which went through two modified methods, enhances the bond strength over 700% in comparison with straight type fiber.

Abstract: In this research article advantages and disadvantages of hollow wall stones (SKTs) were considered, which now are widespread at frame and monolithic construction. Also results of laboratory researches are presented in the article. Definition technique of three physicomechanical characteristics is visually shown: thermal conductivity, sound eliminate, vapor permeability. Separate sambles and fragments of stone layings were made specially for carrying out experiment. Two types of wall stones were compared: with slot-hole and rectangular emptiness. Emptiness differ geometrical parameters therefore they substantially define physicomechanical characteristics.

Abstract: Using SAP is considered as an effective method to counteract autogenous shrinkage of HPC, but the research on the relationship between the water absorption capacity of SAP and the amount of entrained water in HPC is still unclear. In this paper, 6 SAPs with different water absorption capacity were made to discuss the workability and mechanical property of HPC with SAP when different amount of water were entrained. The results showed that the bigger distilled water absorption capacity of SAP is, the smaller the fluidity of cement paste mixed with SAP is, SAP used in HPC should own bigger synthetic pore fluid absorption capacity and smaller distilled water absorption capacity. When 0.03g water/g cement was entrained, the slump of concrete mixed with 4#, 5# and 6# SAP is the same as the slump of ref concrete, and the compressive strength of concrete mixed with 4#, 5# and 6# SAP is also the same as the compressive strength of ref concrete.