Advanced Materials Research Vols. 194-196

Abstract: The effect of Cs⁺ ion and Rb⁺ ion in the molten salt of different proportion on the single panel fire-resistant glass is discussed in this paper. The single panel fire-resistant glass was prepared by the method of ion-exchange, with proper amount of additives and adding KNO₃ and CsNO₃ , KNO₃ and RbNO₃ as the main part of molten salt. The proportion of the molten salt was changed separately, a contrast test was performed to measure the flexure strength. The results indicated that the flexure strength of the single panel fire-resistant glass increased firstly and then stabilized as the ratios of w(CsNO₃)/w(KNO₃) and w(CsNO₃)/w(RbNO₃) increased respectively. With the ratio of w(CsNO₃)/w(KNO₃) =1.5%, the mechanical property of the single panel fire-resistant glass was proper and the maximum flexure strength was 274 MPa. In the case of RbNO₃, the flexure strength of single panel fire-resistant was 244 MPa with the ratio of w(CsNO₃)/w(KNO₃) = 0.3%. According to the research, it is found that the method of ion-exchange of Cs+ and Rb+ into plain glass to prepare single panel fire-resistant glass is feasible, the sample melted under the condition of 1 hour and 780 without any trace of thermal explosion.

Abstract: Although the adhered mortar content affects the properties of recycled aggregate concrete, there are few papers describing those effects. This paper presents the results of a series of experimental study on the effects of adhered mortar content on the quality of recycled coarse aggregate of concrete. 5 kinds recycled coarse aggregates made with heating and rubbing method, mechanical crashing method and separating lightweight particle with water stream method were tested for specific gravity, absorption and adhered mortar content. Specific gravity in oven-dried condition ranged from 2.35g/cm³ to 2.59 g/cm³, absorption ranged from 1.58% to 5.83% and adhered mortar content ranged from 8.0% to 68.4%, depending on manufacturing method of recycled aggregate. Absorption decreased linearly with the increase of specific gravity. Specific gravity decreased and absorption increased with the increase of adhered mortar content. Recycled aggregate made by heating and rubbing method showed lower adhered mortar content corresponding to lower absorption and higher specific gravity, while those made by mechanical crushing method showed higher adhered mortar content corresponding to higher absorption and lower specific gravity. In conclusion, the upper limit of adhered mortar content of recycled coarse aggregate is considered to be 15%, in order to keep up the quality of coarse aggregate and properties equal to natural coarse aggregate.

Abstract: Using waste to produce a new type of air entraining agent (AEA), carrying out research of the concrete’s mixture performance, mechanical properties and frost resistance durability after mixing with the AEA, with results showing that amount of air entrained in the concrete mixture and the water reducing rate increases along with the increase of the addition of the new AEA, and its compressive strength loss laws are similar with that of normal AEAs. During the frost-thaw cycle test, when the weight loss rate has reached its limit, concrete with the new AEA added can withstand almost 300 cycles, and at this time the relative dynamic modulus of the concrete, when the amount of air entrained in it is 4.5%, is 83.5%, and the relative dynamic modulus is 85.4% when the amount of air entrained is 5.3%. The addition of the AEA has obviously improved the pore structure of the concrete, and significantly raising its frost resistance durability.

Abstract: Marshall test design methods are used to design TLA modified asphalt mixture and base asphalt mixture respectively, and their pavement performance is tested. The results showed that there is a transforming coefficient of 1.10 between optimum asphalt content (OAC) of 25% TLA modified asphalt mixture and that of base asphalt mixture, and TLA modified asphalt mixture has excellent high temperature stability, capacity of moisture-resistance damage and impermeability. Construction technology of TLA modified asphalt mixture is similar to that of ordinary asphalt mixture, but the key for it is to control construction temperature, uniformity and compactness of TLA modified mixture.

Abstract: We have made the concrete test blocks, which were blasted by different charge quantities in the semi-infinite soil. Using the SHIMADZU Universal Testing Machine AG-X250kN system, we performed the uniaxial compression test, studied the stress-strain curves of concretes by explosion, under the same condition curing and the standard curing. The results show that, concrete will have higher compression strength by explosion. And there is an optimal charge quantity, when the concrete consumption is given. With this optimal charge quantity, compression property of concrete by explosion is superior to concrete cured at standard.

Abstract: A new kind of self-cross-linked potato starch graft copolymer (PoSt-g-P) was prepared successfully by emulsifier-free emulsion polymerization, in which methyl methacrylate (MMA), acrylic acid (AA) and butyl acrylate (BA) were used as main monomers, and diacetone acrylamide (DAAM) as functionality monomers. The keto-carbonyl group in the potato starch graft copolymer /DAAM could react with adipic dihydrazide (ADH) at ambient temperature to form cross-linked thin film. The film properties of emulsion were measured, which showed excellent properties in hardness, gloss and water resistance. The humidity-sensitive coatings (PoSt-g-P-C) were prepared by the self-cross-linked PoSt-g-P, pigments and fillers. Adipic dihydrazide was used as a cross linking agent and assistant. Its humidity controlling properties were also measured and shown high activity in increasing humidity and dehumidify.

Abstract: This paper measures moisture porosity of explosive lining test pieces after long-term water immersion, so are the test pieces in standard curing condition and in equal curing condition. We have analyzed the measured moisture porosity data of three kinds of test pieces after long-term water immersion. The results indicate that the moisture porosity of explosive lining test pieces is higher than that in standard curing condition and in equal curing condition.

Abstract: The use of fly ashes for cement-replacement purposes, especially in high volumes, decreases rate of early strength development of the steam curing concrete. To resolve it, this paper developed a new steam-cured concrete incorporating fly ash and a chemical activator (gypsum). Experiments were conducted to investigate the mechanical properties at early and later ages of steam and standard curing concretes. The corresponding mechanism was also discussed by testing the microstructure of concretes. Results indicate that the demoulding compressive strength of steam curing concrete with 4% gypsum dosage can meet production requirements, and compressive strength of this concrete at later ages increase well. Compared with that of ordinary pure cement steam-cured concrete, concrete with 4% gypsum has a higher compressive strength gain rate. At an early age, addition of the gypsum can distinctly accelerate the extent of hydration of the steam curing fly ash cement systems, and thus the microstructure of concrete becomes denser. However, in standard curing condtion, the effect of gypsum is not distinct.

Abstract: Laboratory tests were conducted to evaluate the performance of cement stabilized “skeleton-dense structure” aggregate and conventional “suspended-dense structure” aggregate. In this study, both of the aggregates above were stabilized by cement with different cement content (2%, 3%, 4%, 5% and 6%). Performances of the prepared specimens were studied in terms of compaction property, 7 day unconfined compressive strength (UCS), thermal shrinkage coefficient and 30 min erosion quantity. Results indicated that the maximum dry density of cement stabilized “skeleton-dense structure” aggregate is bigger than that of cement stabilized “suspended-dense structure” aggregate slightly. On the contrary, the optimum moisture content of the former is slightly smaller than that of the latter one. Along with the increase of cement content, the 7 day UCS and thermal shrinkage coefficient of cement stabilized two aggregates were all increase, and 30 min erosion quantity of cement stabilized two aggregates were all decrease. At the same cement content level, the 7 day UCS of cement stabilized “skeleton-dense structure” aggregate is greater than that of cement stabilized “suspended-dense structure” aggregate, and the thermal shrinkage coefficient and erosion quantity in 30 min of the former is smaller than that of the latter.

Abstract: High performance concrete will undergo thermal-mechanical degradation or even spalling under high temperature conditions, such as fire, and the safety of concrete structures will be endangered. To prevent concrete from fire damage, the damage mechanism should be thoroughly understood. In this paper, an anisotropic damage model is presented to analyze the thermal-mechanical degradation of concrete. The vapor pressure and the moisture transport are taken into account. The damage evolution history can be traced with the temperature propagation and the degree of material degradation can be predicted through the model.