Advanced Materials Research Vols. 287-290

Abstract: Based on accelerated carbonation test, the variation of carbonation resistance of pumping concrete (C40 grade) with moist-curing time at early ages and fly-ash content was studied. Results indicate that the carbonation coefficient and the accelerated carbonation depth of the concrete increased obviously with a reduction in the moist-curing time at early ages and with an increase in the fly-ash content. For example, in conditions of curing schedules with 28, 7, 3, 2 and 1 d moist-curing at 20 0C with above 95% RH at early ages and then 0, 21, 25, 26 and 27 d air curing at 20 0C with 60% RH, respectively, carbonation coefficients of the concrete incorporated with 30% fly-ash were 2.04, 2.49, 3.16, 3.86 and 5.42 mm/a^0.5 respectively, and thus it can be seen that the calculated times when concrete cover (25 mm) was completely carbonated naturally in now atmosphere (0.04% CO₂) were 164, 104, 66, 44 and 21 years respectively. The results suggest that for the carbonation resistance of the C40 concrete incorporated with up to 30% fly-ash, the moist-curing time of 7 days at early ages should be necessary.

Abstract: To realize the industrial application of online reconstruction technique of steel slag, a pilot-scale reconstruction research of steel slag (SS) with electric arc furnace slag (EAFS) and coal cinder (CC) and its mechanism were investigated. The results show that after reconstruction, the free-CaO content of reconstructed steel slag (RSS) is reduced. XRD analysis indicates that the reconstruction reaction can promote to create more active cementitious minerals (C₂S, C₃S, C₆AF₂ and C₆A₂F) in RSS. Composition adjusting materials formula composing of EAFS and CC at the ratio of 70:30 is optimum, which can meet the standard of the first grade steel slag powder according to Chinese National Standards GB/T 20491-2006.

Abstract: Coking wastewater comprising a lot of ammonia is a good desulfurizer for recycling. Sintering flue gas is characterized by large volume, low sulfur dioxide (SO₂) concentration and large variation amplitude and etc. The purpose for treating waste with waste can be carried out by treating sintering flue gas with coking wastewater. This paper uses a spray tower countercurrent device, ensures the contact between coking wastewater and sintering flue gas, and detects SO₂ concentration of inlet flue gas and outlet flue gas on line by using an automatic flue gas detection instrument. This paper studies on the change regularity for the SO₂ concentration at outlet flue gas during the process of treating sintering flue gas with coking wastewater, the influence of SO₂ initial concentration in sintering flue gas to the removal efficiency of SO₂, the influence of gas-liquid ratio between the sintering flue gas and the coking wastewater to the removal efficiency of SO₂, and the change regularity for the pH value of coking wastewater after desulfurizing. The results show that the sintering flue gas which is treated can live up to the atmospheric pollutant effluent standard of iron and steel industry; the pH value of coking wastewater is reduced after treating, and the conditions for the implementation of subsequent coking wastewater treatment process are provided.

Abstract: This paper examines the effects of the mixture ratio of fly ash/slag, the type of alkaline activators and curing conditions on the workability, compressive strength and microstructure of cementless alkali-activated mortar. The investigation showed that the mixture ratio of fly ash/slag and the type of alkaline activator have significant influence on the workability and strength, whereas the curing temperature has relatively poor effect. An alkali-activated mortar using a binder composed of 50% of fly ash and 50% of granulated blast furnace slag and alkaline activator made of 9M NaOH and sodium silicate in proportion of 1:1 is seen to be able to develop a compressive strength of 65 MPa at age of 28 days even when cured at ambient temperature of 20°C.

Abstract: The magnesium slag is discarded from production of magnesium metal from dolomite. However the magnesium slag is slaked in some factories by means of sprinkling water to prevent from dust pollution. The possibility of slaked magnesium slag (SMS) to play a role of mineral admixture for concrete was investigated by experiments of mortars and concretes prepared with SMS. The results revealed that SMS was still reactive. When SMS is substituted for 30% of cement, its reactivity index is equivalent to that of grade I fly ash (FA). And when SMS is used as mineral admixture to prepare concrete, it contributes to strength of concrete no less than S95 ground granulated blast-furnace slag (GGBS). Better effect of binary or ternary blend can be obtained by combining SMS with GGBS and/or FA. Because the magnesium slag is slaked, SMS has no problem on soundness, so it can be applied in concrete as mineral admixture.

Abstract: Concrete interlocking block pavement is characterized of preferred durability, easy construction and maintenance and low construction cost. It can be widely applied in the rural highway. Based with the project of rural highway in Tongchuan Shaanxi province, the paper studies the mechanism of interlocking blocks, design of the pavement, and construction technology for field application. After one year service for open traffic, the interlocking block pavement is shown to have fascinating economy and service performance for the rural road.

Abstract: High performance polymer mortar and the high strength prestressed steel wire characteristics are researched and analysised in this paper. High performance prestressed polymer mortar system is proposed in the application of concrete structure reinforcement on the basis of those two existing material of china, reinforcement construction process and successful practical applications is also given. This technology organically combine high-performance polymer mortar with prestressed steel with fire resistance, good corrosion resistance, strong anti-aging, anti-cracking, durability and other advantages, so it is worth further study and extension application.

Abstract: This research investigates the mechanical property of the concrete which were mixed with chemical admixtures and treated by magnetic field. Two chemical admixtures were used in this research: Concrete superplasiticizer SW-4 and early strength admixtures CF. Magnetic treated admixtures were obtained by passing liquors through a concrete magnetic-field-generating machine. Test variables included admixture dosage and curing age. Results show that liquor’s conductivity and surface tension have some special changes after treated by magnetic field, and using magnetic treated admixtures could improve the compressive strength of the concrete, reduce the setting times and improve its fluidity and magnetization improved cement hydrate degrees.

Abstract: CaZr_0.9In_0.1O_3-α and BaCe_0.85Y_0.15O_3-α two kinds of solid electrolytes were prepared, and the preparation conditions were determined. DSC-TG curves were used to illustrate the synthetic mechanism of CaZr_0.9In_0.1O_3-α and BaCe_0.85Y_0.15O_3-α, and XRD analyses indicate these two solid electrolytes are single phase after calcining at 1400°C for 10h. The isostatic pressing method and hot injection moulding method were used to prepare CaZr_0.9In_0.1O_3-α and BaCe_0.85Y_0.15O_3-α tubes. Through comparing the apparent density of sintered tubes, it is found that isostatic pressing shaping method is good for improving the compactness of CaZr_0.9In_0.1O_3-α sintered tubes, and hot injection moulding shaping method is good for improving the compactness of BaCe_0.85Y_0.15O_3-α sintered tubes.

Abstract: This paper concerns the use of recycled fine concrete and clay brick aggregates to respectively globally replace natural fine aggregates (sand) in the production of mixed mortar. The fundamental properties such as the compressive strength and the shrinkage ratio of mixed mortar made of the recycled fine aggregates are tested and discussed in detail. The experimental results indicated that it is viable to produce mixed mortar using recycled fine concrete and clay brick aggregates, the compressive strength of mixed mortar made of recycled fine aggregates is lower than that of mixed mortar made of natural fine aggregates and the shrinkage ratio of mixed mortar made of recycled fine aggregates is larger, cured in natural environment.