Effect of CF and RPP on the Mechanical and Electrical Properties of Smart Aggregate

By using redispersible polymer powder（RPP） and carbon fiber（CF） to adjust the flexibility and electrical properties of the smart aggregate, a new kind of smart aggregate with Z type structure was proposed. The study shows that Z type aggregate is more sensitive to the feedback of external force than the prism aggregate in the same loading environment, and it indicates that Z type aggregate is more suitable for the research and application of concrete health monitoring. Although the incorporation of RPP would cause the compressive strength of the aggregates and the elastic modulus of hardened cement mortar to reduce slightly within the dosage of RPP by 2.25% because of the polymer film formed in the internal system, this would improve the deformability of the aggregates. In the early loading stage（in the first 60 seconds）, the intelligent concrete specimens implanted with Z type smart aggregate do not show higher sensitivity as expected, although the resistance change rate changes a little bit more, the overall of it is still in balance. Adding RPP could improve the flexibility of smart aggregates exactly, and it plays an active role in prolonging the life of the smart aggregates. By implanting Z type aggregates the damage and failure of the concrete structure could be predicted accurately in this study. The results of this paper will help to promote further research and application of intelligent concrete.

Properties and Microstructures of Full Graded Concrete Containing Varied Impurity Aggregate

We investigated mechanical properties of concretes made with impurity aggregates of different combinations. Besides the mechanisms were explored by EDS, CT, and hardness testing. The results showed that fully rust-stained and surface rust-stained sandstone aggregate had significant adverse impact on the compressive strength of concrete while sandstone aggregate had a much more obvious impact on the ultimate tension of concrete. Concrete crack was more prone to expand along surfaces and the micro-hardness of interfacial transition zone of different aggregates was ranked in decreasing trend as sandstone, slate, SR sandstone, marble, and FR sandstone. The cluster growth of long needle-like ettringite crystal and strong preferential growth trend of Ca（OH）2 crystals would result in wider interfacial transition zone range of concretes made with fully rust-stained sandstone and marble aggregate, respectively. Therefore, the impurity aggregate content should be strictly controlled during aggregate selection.

Quality prediction of freshly-harvested wheat using Gluto Peak during postharvest maturation

Much recent researches have demonstrated that the quality of freshly-harvested wheat could be improved during postharvest maturation by determinating the rheological properties.However,this process is time-consuming and complex.This study aimed to provide a rapid and convenient method for predicting wheat quality during postharvest maturation by use of Gluto Peak device.Farinograph and Extensograph were used to determine the rheological properties of four wheat samples(WT1,WT2,WT3,WT4)stored under different conditions(WT1:15℃,50%RH;WT2:20℃65%RH;WT3:28℃75%RH;WT4:35℃85%RH)for a total of 10 weeks,and Gluto Peak test was used to determine the gluten aggregation properties of the four samples.Correlation analysis was also conducted between the rheological properties and the gluten aggregation properties.Results of rheological properties showed that all Extensographic properties(dough extensibility,resistance,maximum resistance and area)of the four samples increased along with the storage time,and the Farinographic properties(water absorption,dough development time,dough stability time,and farinograph quality number(FQN))had the same tendency,indicating that the rheological properties were improved considerably with storage time extending.The Gluto Peak curves revealed that Peak Maximum Time(PMT),Brabender Equivalents Maximum(BEM)and Energy to Maximum Torque(En MT)of wheat flour of the four samples varied greatly,particularly the PMT and En MT of the samples WT3 and WT4 increased remarkably.Results of correlation analysis showed that En MT had significant correlation with water absorption and area(P<0.05)for sample WT1,and also showed significant correlation with dough development time(P<0.05)for sample WT2.For sample WT3,PMT was significantly correlated with the dough development time,extensibility,area(P<0.05),and FQN(P<0.01);and En MT was in significant correction with water absorption(P<0.01),and dough stability time,FQN,extensibility,maximum resistance and area(P<0.05).For sample WT4,both PMT and En MT had significant correction with area(P<0.05).The study indicated that the Gluto Peak test is effective in quality prediction for the freshly-harvested wheat during postharvest maturation,making it possible to realize rapid wheat quality detection and evaluation in storage period.

Synthesis,characterization,photophysical and electrochemical properties of oxygen bridged twisted heptatomic biphenyl substituted perylene diimides

The perylene diimide derivatives（s-THBPDI and d-THBPDI） bearing oxygen bridged twisty heptatomic biphenyl in the bay positions of the perylene core through acetylene bond were designed and synthesized.The photophysical properties of the functionalized dyes were investigated in solution and solid state by UV-vis and photoluminescence（PL） spectra.Their UV-vis and PL spectrum both exhibited the different concentration-dependent behaviors due to the difference of chemical structure.Moreover,cyclic voltammetry results indicated that the introduction of oxygen bridged twisted heptatomic biphenyl could decrease the LUMO energy level of the perylene diimide effectively and made it promising material in photoelectric devices.

An empirical method for estimating surface area of aggregates in hot mix asphalt

Bitumen requirement in hot mix asphalt （HMA） is directly dependent on the surface area of the aggregates in the mix, which in turn has effect on the asphalt film thickness and the flow characteristics. The surface area of aggregate blend in HMA is calculated using the specific surface area factors assigned to percentage passing through some specific standard sieve sizes and the imaging techniques. The first process is less capital intensive, but purely manual and labour intensive and prone to human errors. Imaging techniques though eliminating the human errors, still have limited use due to capital intensiveness and requirement of well-established ]aboratories with qualified technicians. Most of the developing countries like India are shortage of well-equipped laboratories and qualified technicians. To overcome these difficulties, the present mathematical model has been developed to estimate the surface area of aggregate blend of HMA from physical properties of aggregates evaluated using simple laboratory equipment. This model has been validated compared with the existing established methods of calculations and can be used as one of the tools in different developing and under developed countries for proper design of HMA.