Key Engineering Materials Vol. 509

Abstract: The structure of the polycarboxylate superplasticizer (PCE) and the relationship between the structure and the performance of PCE were summarized and analyzed. Based on these results achieved so far, the consensus and the unified opinions were presented while the ambiguous and contradictory points were compared and discussed. Furthermore, the different effect on performance caused by different structure such as side chain length, degree of polymerization, side chain density, functional group were discussed systematically. Finally the existing problems and the measures to be taken in the future were proposed

Abstract: S-doped TiO2 nanomaterials (S-TiO2) synthesized by solid state and liquid state reaction route were used for the visible light degradation of Rhodamine B. The results show that at 20°C，pH=5, the rule of pseudo-first-order reaction and high catalytic activity were found in the visible light degradation of RhB on the S-TiO2 nanomaterials and pure TiO2. Within 80 min, the visible light degradation ratio of RhB is 97.9%, which is 6.6 times for pure TiO2. The reaction conditions such as the initial concentration, pH value, the sorts of metal ions, and consumption of catalyst affect the reaction rate constant of S-TiO2 material. The addition of Cu2+ enhances the visible light degradation rate of 28.6%, but Cr3+ decreases greatly the reaction rate of RhB.

Abstract: In this paper, ordered mesoporous silica film as a novel antireflective coating was directly synthesized via evaporation induced self-assembly (EISA) process with cetyltrimethylammonium bromide (CTAB) as template surfactant. The mesoporous silica film exhibits ordered 2D hexagonal microstructure as demonstrated by transmission electron microscopy (TEM) and small angle X-ray diffraction (SAXRD). The average transmittance of the coated glass is about 98%, which indicates an increasing transmitted light of 7.5% in the wavelength between 400nm and 800nm. The mechanical performance and hydrophobicity tests prove that the films have excellent scratch resistance and long-time stability. The results of the characterizations and tests show that the film prepared by this convenient method would be very useful and promising for lots of commercial applications.

Abstract: The recycled concrete was prepared by using the high-strength artificial aggregates. This kind of concrete can be completely regenerated to be cement, and the recycling utilization of the concrete can also be truly realized. The frost resistance and influencing factors of the recycled concrete were studied. The results show that the mechanical performance and frost resistance of artificial aggregates recycled concrete are better than those of the ordinary concrete under the same water/cement ratio condition. When the water/cement ratio is 0.40, the relative dynamic elastic modulus, weight loss and frost durability factor of the recycled concrete are 98.7%, 0.5% and 65.8 after 200 times freeze-thaw cycles. When the fly ash and silica fume were added into the recycled concrete, the frost resistance can be improved. The optimal amounts of fly ash and silica fume are 30% and 15% of cement by weight, respectively. The recycled concrete was prepared with the optimal fly ash and silica fume content, respectively. After 200 times freeze-thaw cycles, the relative dynamic elastic modulus of the recycled concrete are 99.1% and 99.2%, and the weight losses of the recycled concrete are 0.4% and 0.3%, and antifreeze durability coefficient of the recycled concrete are 66.07 and 66.13. Therefore, the recycled concrete with silica fume has better frost resistance performance than that with fly ash as admixture.

Abstract: With the development of construction project the durability of concrete is becoming more and more prominent, and surface coating is an effective measure to enhance the durability of concrete. Water-based silicone acrylic emulsion coating and water-based fluorocarbon resin coating were chose as prime and topcoat respectively. The impact of the coating’s thickness and viscosity on the durability of concrete and the relationship between the viscosity of the coating and its penetration depth were testified by chloride ion permeability-resistance property of concrete. The results show that thickness is proportional to the protective performance of the coating, and the penetration depth highly depends on viscosity. And the result of coating-4 viscosity method shows that samples with viscosity between 15 and 25 seconds have better chloride permeability resistance.

Abstract: The pollution soil from tar workshop’s foundation soil in a steel work, first of all, the main organic pollutants in pollution soil are examined by the Pony Test Center. Then, the volatility of the pollution soil at different temperature was studied by thermo gravimetric (TG) analysis coupled with Fourier transform infrared spectroscopy (FTIR). At last, by adding standard reagents of PAHs respectively, their volatility of different temperature period was confirmed. The results indicated that the main organic pollutants in the contaminated soil were fluorene, acenaphthene, phenanthrene, fluoranthene, pyrene and so on, the total content is about 156.39ppm. the weight loss of pollution soil mainly occurred at the temperature ranges of room temperature to 215°C, 215~670°C and 670°C~850°C. There were H₂O and CO₂ coupled with the weight loss. When temperature increased further up to and above 850°C, the weight tended to be stable. The volatilization of PAHs is mainly in the section of 215~670°C, and their fastest volatilized temperatures in pollution soil were lower about 30°C than their respective boiling points.

Abstract: Layered double hydroxides (LDH) can provide the ion-exchange ability and the addition of LDH can affect the chloride-ion transfer in the concrete. The effect of LDH on the chloride-ion penetration is investigated in this study. Concrete samples contained different addition of LDH are designed in the experiment and tested by electric flux method and NT Build 443 method. The experimental results show that the addition of LDH can solidify the chloride-ion in concrete and slow down the transfer of chloride-ion, which enhanced the concrete resistance of chloride-ion penetration.

Abstract: In this paper, the influence of steel slag and its pretreatment method on properties of phosphorus slag cement has been studied. The hydration process and microstructure were studied by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that, the problem of long setting time of high content phosphorous slag cement can be effectively solved by adding steel slag and pretreated steel slag. About 6% content of steel slag could promote the early hydration of phosphorus slag cement and reduced the initial setting time 2 hours. Grinding phosphorous slag and steel slag with different water content, the initial set time of phosphorus slag cement for 6 hours has reduced to 2.5 hours without changing the strength. Ageing the mixed grinding power of phosphorous slag and steel slag and keeping 2.5 hours of the initial set time, the early cement strength can increase 3 MPa.

Abstract: The physical and chemical evolutions, including strength, porosity, chemical and mineral compositions, of properties of steel slag bricks prepared by both alkali activation and accelerated carbonation were investigated. The results show that alkali activation provides the initial properties, while accelerated carbonation plays a dominant role in such final performances as strength, porosity, chemical and mineral compositions of steel slag bricks. The steel slag bricks with a compressive strength of 33.8MPa, carbonation degree of 8.92% and porosity of 23.25% were successfully prepared after accelerated carbonation curing (T=50°C, RH=60%, P=0.25MPa, ρ_CO2=80% by volume) for 120min.

Abstract: The impact of recycled fine aggregate and powder on the mechanics and thermal performance of recycled concrete hollow blocks was discussed in this paper. The results showed that 30% recycled fine aggregate and powder have slight affect on the strength of recycled concrete hollow blocks. But the strength reduced significantly when the replacement is above 50%. The impact of recycled fine aggregate and powder on the performance of concrete hollow blocks with high strength grade is notable . The heat transfer coefficient of recycled concrete hollow blocks with 30% recycled fine aggregate and powder was equivalently to ordinary concrete hollow blocks.