In this paper, the effect of particle morphology on bipolar diffusion charging is studied. A modified tandem differential mobility analyzer (TDMA) method used to measure the charge distribution of submicron particles in the range of 70-300 nm is described in detail. The method requires an independent measurement of the neutral fraction, followed by the measurement of the size-dependent charge distribution, which requires the knowledge of the neutral fraction. The method was validated experimentally using dioctyl sebacate and ammonium sulfate spherical particles and compared with Fuchs' theory. Diesel particles and silver aggregates were used to evaluate the impact of morphology on charging. The results show that aggregates have a slightly lower (about 7%) neutral fraction than spheres. These results are in agreement with the predictions of Lall and Friedlander's theory and previous studies. However, results from charge distribution indicate that more (about 46%) particles are negatively charged than predicted by Lall and Friedlander's theory, while 32% fewer particles are positively charged. This relatively large asymmetry between the negative and the positive charge fraction is not fully predicted by either Fuchs' or aggregate charging theories. Our results suggest that the current inversion method of scanning mobility particle sizer (SMPS) data, based on Fuchs' or Lall and Friedlander's distribution, would underestimate the total number concentration by about 15% or 27% if applied to diesel aggregates.

The influences of fly ash, phosphorus slag powder and slag powder on the chemical shrinkage were researched in this paper. The results indicated that chemical shrinkage of cement paste was mainly relative to the mineral composition of cement, and three kinds of admixture could all make chemical shrinkage of cement paste reduce in early stages, but the chemical shrinkage of cement paste increased in later stages after mixing slag powder and phosphorus slag powder, and the activity of slag powder was higher than phosphorus slag powder, and fly ash could be used to inhibit chemical shrinkage of cement paste. The prediction model of chemical shrinkage of cement based materials was established.

Upon large demands from southwest of China where a large number of hydropower stations are schemed or under construction with presence of a variety of aggregates, it is of necessity to launch a comprehensive investigation on influence of aggregates on properties of concrete which was rarely reported before. Four types of aggregates selected from different construction sites were used to conduct tests, and results indicated that water absorption of aggregates exhibited a consistent rising tendency over 180 days and it had close relationship with autogenously shrinkage of concrete which varied in the manner that high water absorption of aggregates produced more obvious shrinkage. With employment of advanced temperature and stress machine, concrete made with diorite and basalt was rated better than limestone and natural granite concrete in crack resistance based on comparison of cracking temperature and thermal impact according to RILEM TC119.

The strength, ultimate tensile value, compressive elastic modulus and drying shrinkage of polyvinyl alcohol fiber reinforced concrete were studied by tests, and its crack resistance property was also studied by plate method and temperature stress testing machine. The test results showed that PVA fiber could improve the tensile strength and ultimate tensile value of concrete, lower its compressive elastic modulus and drying shrinkage, restrain its early plastic shrinkage and drying shrinkage cracks, reduce its cracking temperature and improve the crack resistance property of concrete, moreover, the effect of long PVA fiber was better.

The computed tomography was introduced to track the development of cracks in cement matrix and Interfacial Transitional Zone (ITZ) of MgO concrete under load to failure and EDS and BEI was employed to investigate the enrichment characteristics of elements in vicinity of ITZ area. Results indicated that cracks intended to extend along boundary of ITZ area which aggravated ITZ as the weak link of concrete structure. The morphology of products of hydration in ITZ area and cement matrix was similar but differed in amount, size and crystal features. Elements Ca, Si, Al and Mg had tendency to enrich in ITZ zone but differed in accumulation extent in orders. MgO was non-uniformly distributed in concrete, fully mixed in construction though, richer in cement matrix than in ITZ, yet MgO later inclined to migrate to ITZ area and the gap in between was mitigated with in-depth hydration.

C40R60 High volume fly ash (HVFA) concrete were adopted for the continuously casting massive foundation slab of Tianjin Tower, which has a volume of about 20 000 m3, to decrease the risk of cracking during the construction process. Suitable raw materials and mix proportion were chosen. The properties of hardened concrete cured under different conditions were investigated. A mock-up of massive structure with the dimension of 4.5×4.5×4m was cast using determined concrete. The temperature development in the core of structure was measured. The results show that the temperature rise in the core is relatively low and the compressive strength curing under the standard condition for 60 days is 54.3MPa. HVFA concrete is much suitable to the massive concrete structure in which elevated temperature would be kept for a long time.

The morphology and elements enrichment in the vicinity of interfacial transition zone was investigated with employment of SEM, EDS and BEI. Results indicated that the morphology of products of hydration in ITZ area and cement matrix was similar but differed in amount, size and crystal features. Elements Ca, Si, Al and Mg had tendency to enrich in ITZ zone but differed in accumulation extent in orders. MgO was non-uniformly distributed in concrete, fully mixed in construction though, richer in cement matrix than in ITZ, yet MgO later inclined to migrate to ITZ area and the gap in between was mitigated with in-depth hydration.

Elevated concentrations of diesel exhaust have been linked to adverse health effects. Filtering facepiece respirators (FFRs) are widely used as a form of respiratory protection against diesel particulate matter (DPM) in occupational settings. Previous results (Penconek A, Drążyk P, Moskal A. (2013) Penetration of diesel exhaust particles through commercially available dust half masks. Ann Occup Hyg; 57: 360-73.) have suggested that common FFRs are less efficient than would be expected for this purpose based on their certification approvals. The objective of this study was to measure the penetration of DPM through NIOSH-certified R95 and P95 electret respirators to verify this result. Gravimetric-based penetration measurements conducted using polytetrafluoroethylene (PTFE) and polypropylene (PP) filters were compared with penetration measurements made with a Scanning Mobility Particle Sizer (SMPS, TSI Inc.), which measures the particle size distribution. Gravimetric measurements using PP filters were variable compared to SMPS measurements and biased high due to adsorption of gas phase organic material. Relatively inert PTFE filters adsorbed less gas phase organic material resulting in measurements that were more accurate. To attempt to correct for artifacts associated with adsorption of gas phase organic material, primary and secondary filters were used in series upstream and downstream of the FFR. Correcting for adsorption by subtracting the secondary mass from the primary mass improved the result for both PTFE and PP filters but this correction is subject to 'equilibrium' conditions that depend on sampling time and the concentration of particles and gas phase hydrocarbons. Overall, the results demonstrate that the use of filters to determine filtration efficiency of FFRs challenged with diesel exhaust produces erroneous results due to the presence of gas phase hydrocarbons in diesel exhaust and the tendency of filters to adsorb organic material.