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I.Introduction In recent years, with the development of highway construction in China, the number of highway and bridge have reached 284000, about 10.65 million meters long.
Table 2 Fault diagnosis result and remedy measures Fault phenomena Fault diagnosis result Remedy measure The cracks (>3mm) in tensile area of girder, mainly in middle part of girder Big bending stress value owing to Vehicle overloading (1) Increase section on every side of girder (2) Make reinforced concrete cover (3) Make steel hoop and then apply wire mesh cement on it Longitudinal cracks along the girder Rust of reinforcing steel bar Make grooves along the cracks, filling cement mortar epoxy grout in grooves Unevenness, honeycomb cavity and steel bar appearance on structure surface Construction quality problems (1) Screed with same grade cement mortar (2) Chisel off the protrudent aggregate grain, rinsing this part with pressure water, and then fill this part with grain size 10～20mm pea gravel concrete.

The fly ash used for concrete will be of an average grain size, determined during the grinding experiments by Šulc and Svoboda [3].
Technical quality conditions number 18 [5] states that the minimum air content in the fresh concrete with grain size up to 16 mm for exposure class XF4 is 4,5%.

The analysis of a number of the products shows that these microsheets have an average diameter of 6.25 μm and a thickness of 90nm.
As we all know, when the infrared light acts on the sample, just only make the Er3+ and Yb3+ ions in the small thickness of the surface and low-energy state electronic can absorption infrared photon transition to the high-energy state, population to a higher level of metastable, but Er3+ and Yb3+ ions in the grain interior can not absorb infrared photons of outside radiation.
Therefore, the thicker and larger grains, the lest effectively stimulated the Er3+ and Yb3+ ions, lead to lower emission intensity inevitably [13].

Saeidi et al [2] demonstrated via EBSD that most initial voids were nucleated between closely spaced martensite islands located between two large ferrite grains, where martensite islands were quite isolated.
Finally, by using software HYPERMESH, the model was generated with an edge length of 25μm and element size of 0.15μm, and the total element number was 29070.
Sharp sub-cracks in grain-scale with different sizes were ingrained on the bottom of the RVE model, simulating a microscale tensile test on a geometrically imperfect sample.

Specimen names with the features Name Laser power Number of layers Shape Test position/ direction S1 1800 W 1 cuboid Section on YOZ plane S2 2100 W 1 cuboid Section on YOZ plane S3 2400 W 1 cuboid Section on YOZ plane S4 2400 W 4 cuboid Section on YOZ plane S5 2400 W 4 I-shaped X-axial, in layer 1 S6 2400 W 4 I-shaped Y-axial, in layer 1 S7 2400 W 4 I-shaped X-axial, in layer 2 S8 2400 W 4 I-shaped Y-axial, in layer 2 Microstructural and mechanical characterization.
The most obvious change of this part is the coarsening of the grains and the formation of secondary Widmanstatten structure.
The grain size inclined to be lager which is have adverse effects on fracture strength.

The size of prior austenitic grain boundaries of the steels are almost the same (about 20μm).
These microstructures consisted of a wide lath-martensite structure matrix and fine dispersed MA-like phase, which is a mixture of narrow lath-martensite and retained austenite and isolated on the block, packet, and prior austenitic grain boundaries.
The numbers of voids at the break section in steels B and C were the same as that in steel A, although the size of the voids in steel B were larger than those in steels A and C.

However, there is a limited number of publications concerning the hybrid effect of Al2O3 and graphene on aluminium-based composites [13, 14].
The preparation procedure started with mixing the aluminium powder using ball milling process to reduce the grain size and ensures the dispersion of reinforcement through the matrix phase.
The commercial alumina powder (Al2O3) used in this work has a grain size of about 10 μm.

-12 -9 -6 -3 0 3 6 9 12 Y/×(10-4m) Be SS 4 -4 -3 1 -2 4 0 1 2 3 -1 3 2 Fig. 2 Sketch map division nuits(The number is units,s sign) x /(×10-4m) Fig. 1 The diffusion couple C1 0 Be SS C2 In a few hours, the diffusion distance is about hundreds of micrometers, therefore, divided only finite element in very small zone near the Be/SS bonding interface (shown in Fig. 2).
The higher the heating temperature, the faster the diffusion and the better the bonding joint strength, but recrystallization and phase transformation may take place at high heating temperature, which leads grain growth and composition segregation and strength decline in the bonding joint.
But diffusion bonding temperature is generally above recrystallization temperature, and may lead grain growth in longer holding time, especially the holding time should be controlled for the joints on posslble forming brittle intermetallic compounds which reduce the joint performance . 0≤ t≤7200s （3） 100 o Concentration curve of Fe l Concentration curve of Be Distance, x /μm Atom concentration,C/% a 90 -100 100 -25 -50 -75 0 75 50 25 80 70 60 50 40 30 20 10 0 Fig.5 The concentration profile of Be and Fe under 1023K/60MPa and different time, (a)1800s, (b)3600s, (c)5400s Atom concentration, C/% o Concentration curve of Fe l Concentration curve of Be Distance, x/μm c -100 100 0 -25 -50 -75 75 50 25 100 10 90 80 70 60 50 40 30 20 0 o Concentration curve of Fe l Concentration curve of Be Distance, x/μm Atom concentration, C/% b -100 0 -25 -50 -75 75 50 25 100 90 80 60 50 40 30 10 20

Number of specimens from the bar for hardness test was three, and mean value of specimens was collected.
An elevated brittleness usually occurs, at medium carbon steels, from an excessively high temperature of reheating which promotes coarsening of austenitic grain.
However, the pearlite fraction is small and the grain size of steel is fine, as mentioned above, thereby it is considered that heating process applied during hot forging is reasonable.

However, because of the applications of porous media, it will be jammed by the mineral grains easily. (2)Gravel layer microbubble generator: The gravels will be placed in the grid cell lattice, the diameter of which is 80-200mm, and then there will be 500-600mm thickness gravel layer.
This structure reduce the clogging of mineral grains, but the air consumption is much more than others, and the size of the bubbles generated is not regular, which will have some bad effects on the mineral separation. (3)Electrolytic microbubble generator: The microbubbles, which are generated by this type generator, will be very homogeneous in density, and the diameter of the microbubbles is 0.02-0.06mm.
In the flotation process, the interaction between the bubbles and the particles are as follow: (1) Collision: according to the Stocks’ number, collision can be divided into viscous collision and inertial collision.