Search results

Table 2 Strength of concrete at 28-day age serials splitting strength [MPa] compressive strength [MPa] serials splitting strength [MPa] compressive strength [MPa] A1 3.67 36.5 B3 3.79 49.6 A2 4.29 45.2 C1 4.06 63.7 A3 5.21 56.8 C2 4.52 75.9 B1 4.79 54.3 D2 4.05 58.3 B2 4.34 52.9 E3 4.47 65.7 Table 3 Porosity and permeability of concrete at 28-day age Item Serial number A1 A2 A3 B1 B2 B3 C1 C2 D2 E3 porosity ratio [%] big pore 2.99 2.25 1.63 0.81 0.87 0.98 0.43 0.19 0.56 0.24 total pore 10.93 9.33 7.94 6.40 5.49 5.33 5.92 3.57 4.53 3.35 charge amount within 6 hours 3561 2792 2418 851 294 247 479 196 126 91 The resistance to physical attack was investigated by measuring specimens suffering respectively long-term immersion and dry-wet cycle in saturated sodium sulfate solution at 22°C.
Fig.1 shows the coefficient of concrete to sulfate attack changing with number of wet-dry cycles.
The concrete is close-grained and impermeable; therefore, the ingressive ions cannot easily penetrate into the concrete matrix.
The grains of CH is fine, the hydration gels and fine fly ash granules are packing densely and there is no growing space for ettringite and gypsum development, and it is also difficult for sodium sulfate to ingressive in.
The secondary C-S-H deposited in the pores thereby makes the concrete close-grained and impermeable and, therefore, the sulfate ions cannot easily penetrate through the concrete matrix [4].

Table 1 Evaluation index system and weight of the development of agricultural circular economy in China Target level Criterion level Index level Calculation method Index Weight Index Weight Development level of agricultural circular economy Economic and social development 0.15 Rural per capita net income (Yuan) 0.20 Net Income of Rural household/ Rural households resident population Land output level (Yuan/hm2) 0.35 Total value of farm output / agricultural acreage Per capita share of grain (kg/people) 0.20 Grain yield / Total population Per capita amount of meat (kg/ people) 0.15 Production of meat / Total population Aquatic products per capita possession (kg/people) 0.10 Output of aquatic products / Total population Reduced input of resources 0.35 Fertilizer use intensity (kg/hm2) 0.25 Fertilizer input / planting areas of farm crops Pesticide use intensity (kg/hm2) 0.25 Amount of pesticide application / planting areas of farm crops Application level of agricultural film (kg/hm2)
coefficient (%) 0.45 Effective irrigation area/ agricultural acreage Utility contribution rate of fertilizer (Yuan/ kg) 0.15 Total value of farm output / fertilizer use amount Multiple-cropping index (%) 0.15 Crop sown area / agricultural acreage Ecological environment 0.20 Per capita arable land (hm2/people) 0.15 Agricultural acreage /total population Land area covered with trees (%) 0.40 Forest land area / Total land area Ecological environmental disasters coefficient (%) 0.45 Inundated area / Disaster area Evaluation method Multi index comprehensive evaluation model was selected to evaluate the development level of the agricultural circular economy of China, and the mathematical equations are as follows: 1，2，……, （1） 1，2，……, （2） Where, ATi is the comprehensive index of development level of agricultural circular economy of China, Wi is the weight of index of criterion level, Bi is index of criterion level, Ti is evaluation region, n is number
Cij is index of index level, Wij is weight of index in index level, and m is number of index of index level.
The central region is the most important grain production region of China.

It can be deduced from the fact that the lattice strain decreases as the Al content increases that some Al atoms go into Sb/Te lattice sites by substituting for Sb or Te rather than by the other two possibilities and that the Al-Sb and Al-Te contents may exist as microcrystalline grains around the crystalline Sb2Te3 grains.
These microcrystalline grains serve as centers for suppression of the amorphous-to-rhombohedral phase transition, consequently improving the system stability.
Acknowledgments This work was partially funded by the International Science and Technology Corporation Program from the Ministry of Science and Technology of China (MOST) under award number 2010DFB53890, National Natural Science Foundation of China (Grant numbers: 11104317 and 10834004) and Suzhou Science and Technology Program (SYG201332).

Hence, its function as stabilizer may provide the stability of the tetragonal phase increases with reduced zirconia grain size.
However, the microstructure with fine grain size of Ca-SZ sintered at 1400oC indicated rough surface compared to the Ca-SZ sintered at 1200oC and 1300oC.
This is due to the behaviour of the grains at the highest sintering temperature.
Acknowledgements The authors would like to thank the financial supports provided by the Research University Grant (RUI) from Universiti Sains Malaysia, with the grant number: 1001/PPSG/8012311, and Science Fund Grant from the Ministry of Science, Technology and Innovation (MOSTI) with the grant number: 07-01-05 SF0845 (305/PPSG/6113701).

They considered that the excess vacancies gradually annihilate at available sinks represented by jogs at dislocations, grain boundaries or free surfaces.
The model accounts for the evolution of the total number of precipitates and the size and mean chemical composition of each precipitate and the matrix.
The model can describe the interaction of a large number of precipitates with different chemical compositions and different sizes via diffusion in the matrix.
Dislocation density, grain size, Young’s modulus of the matrix, volumetric misfit, the shape of the different precipitates and nucleation site preferences were taken from the work of Lang et al. [6].
In the current work the yield strength of the material during ageing was computed using physical models that take into account intrinsic grain boundary, solid solution and precipitate strengthening contributions.

The laser particle analyzer test showed that the materials belong to the ultra-fine tailings, whose content of -20μm ultra-fine grains accounted for 54 wt%, -37 μm accounted for 69 wt% and -74 μm accounted for 87 wt%.
The particle sizes of the rocks were milled to -10 mm, the content of -5 mm grains accounted for 92.03 wt%, and -74μm accounted for only 3.53 wt%.
The range R refers to the maximum difference value in each experimental run for each influential factor, given as follows: Rj = maxKr – minKr (1) where, j is the sequence number of the influential factors, j=1, 2, …N; r is the sequence number of experimental run for each factors, r=1, 2, …M; Kr is the average of all runs of r for factor j.
Conclusions (1) The ultra-fine tailings with 54 wt% -20μm grains are propitious to produce the cemented paste backfill for open stope mining with sequent backfilling method.

General structure, fineness of grain, compactness, porosity and absorption, hardness, resistance to weather, weight and strength are some of the characteristics of good gravels Spenser [11].
This is an indication that highest numbers of people in these trades are middle aged, strong and capable.
The literacy level of the practitioners was very low. 54% of gravel suppliers had primary education with few number of degree holders who were contractors among them.
(ii) 52% of the respondents said that in terms of grain size, the gravels contained different sizes from fine to coarse i.e. all-in-one, while 48% submitted that the gravels were very coarse.
Table 3: Technical Variables of the Gravels from Selected Location in South Western Nigeria State Grain size (%) Grading Shape Texture Cleanli-ness Treatm-ent Effect of Transpo-rtation Lagos All-in-one=38 Sandy= 0 Coarse=62 100% WG Rounded=17 Angular=8 Irregular=75 Rough=42 Smooth=48 Clean=98 Dirty=2 Washed=13 Unwashed=87 Sieved=0 Sig Ef=100 No Ef= 0 Fixed= 0 Ogun All-in-one=59 Sandy= 0 Coarse= 41 100% WG Rounded=24 Angular=7 Irregular=69 Rough=45 Smooth=55 Clean=94 Dirty=6 Washed=17 Unwashed=82 Sieved=1 Sig Ef=100 No Ef= 0 Fixed= 0 Oyo All-in-one=76 Sandy= 0 Coarse= 24 100% WG Rounded=10 Angular=10 Irregular=80 Rough=54 Smooth=46 Clean=95 Dirty=5 Washed=21 Unwashed=79 Sieved=0 Sig Ef=100 No Ef= 0 Fixed= 0 Osun All-in-one=90 Sandy= 0 Coarse= 10 100% WG Rounded=22 Angular=7 Irregular=71 Rough=54 Smooth=46 Clean=93 Dirty=7 Washed=17 Unwashed=83 Sieved=0 Sig Ef= 96 No Ef= 4 Fixed= 0 Ondo All-in-one=15 Sandy= 0 Coarse= 85 100% WG Rounded=3 Angular

Group Number Surface condition A A1～A16 cast surface B B1～B16 smooth machined surface, Ra=0.4 μm C C1～C16 rough machined surface, Ra=1.6 μm D D1～D17 rough machined surface, Ra=3.2 μm Fatigue Testing.
For a short time, they increase in size and form the outer equiaxed zone with fine grains [8].
Then, those crystals which can grow parallel and opposite to the heat flow direction will develop most rapidly, leading to the formation of an interior columnar zone with coarse grains.
The cast defects in specimens of group A reduced the fatigue strength noticeably so that the fatigue strength of group A is less than that of group B, even the grain size of group A is finer.
The cast defects on the surface of group A, which deteriorates the fatigue behavior, together with finer grain size which benefits the mechanical properties, lead to a lower fatigue strength compared with group B, but a higher value compared with group C and D.

If filling mould ability is poor, the cavity, such as runner or gate, will be blocked by primary grains and the molten alloys will have to stop flowing or filling, with the result that many casting defects such as misrun, cold shut, shrinkage and so on will come into being and that castings will turn out to be the rejects[3-6].
Feasibility Analysis of Evaluating Filling Mould Ability by Surface Tension According to the Mechanism of Alloy Cessation Flow put forward by Flemings[13], alloy cessation flow is ascribed to the results that the available gate diameter is lessened by the increase of solidifying layers and the metal flow is blocked by the dendritic grains crystallized, and the formula of calculating the flow length X of the molten alloys is as flows
After a period of fixed time, the up-down movement mechanism will lift the detector and crimpling mechanism automatically and the computer will calculate the numbers N of bubbles and pressure difference P∆ in the capillary.
On the contrary, when Al-Si alloy is unmodified, although the surface tension is relatively higher as compared with that of modification, the flowability is principally affected by the shape of grain during solidification.
The cavity is prone to be blocked by the coarse dendritic grain, which results in the poor change of flowability.

Another effect, which can influence the damping of cold rolled specimens, is the grain size [5, 10].
In our previous research we found out that increase in grain size can cause an increase in damping for grain sizes higher than 200 µm for Cu - Al - Mn shape memory alloys [5].
Fig. 4 a shows predominantly the globular structure with grains of β austenite.
In both cases the number of moveable interfaces decreases and causes a decrease of damping.