Advanced Materials Research Vols. 1004-1005

Abstract: In order to study the suppression effect of increasing concrete shrinkage induced by limestone powder, the aliphatic water reducer and polycarboxylate superplasticizer was used in experiments about effect of limestone powder content on concrete shrinkage. The results showed that the concrete shrinkage increased as the limestone powder content increasing. Comparing to the aliphatic water reducer, the polycarboxylate superplasticizer showed obviously effect on concrete shrinkage suppression. Besides, the polycarboxylate superplasticizer can reduce the sensitivity of concrete cracking. The polycarboxylate superplasticizer using in concrete can effectively reduce the emission amount and environmental pollution in the production process of artificial sand, simultaneously, this is helpful to improve the volume stability of concrete.

Abstract: This paper introduces the present situation of existing residential building energy saving reconstruction of Anshan area, the result of the analysis is that the renovation of retaining structure is the key of the reconstruction of existing residential buildings of Anshan. Exterior wall area ratio of the total area of the building envelope accounts for quite large, so transformation of exterior wall is the key. Energy saving wall approach divided into external wall insulation and exterior insulation. Analysis of energy-saving measures by the external wall insulation, and the external wall of a residential district in Anshan city and analysis of thermal insulation and energy saving renovation case, better energy-saving effect, energy saving measures of external economy more external insulation, the region has provided the reference and basis transformation of external wall energy-saving residence building.

Abstract: According to the engineering characteristics,the project was divided into four typical operating conditions,the deformation rules of deep foundation pit at subway station in tunneling are studied with the method of FLAC3D numerical simulation,the supporting structures choose by the bored piles and interior support. The analysis of the horizontal deformation of the retaining structures,the axial force changes of steel support,the settlement law and the influence sphere of surrounding soil. For installation of prop structures on the performance of deep excavations is investigated through numerical analysis with site specific subsurface conditions,The conclusion in this paper can provides reference for the reasonable design and safety construction of deep foundation pit.

Abstract: Iron tailings are mineral wastes obtained from industrial processing and magnetic separation of iron ore. Foam concrete with iron tailings can be made with iron tailings, cement, fly ash, silica fume, polypropylene fiber, superplasticizer, early strength agent, accelerating agent and foaming agent. The influences of polypropylene fiber on the crack resistance and frost resistance of foam concrete have been investigated in this study. Further, the microstructure of foam concrete was observed. This result demonstrates that polypropylene fiber has greatly increased the crack resistance and frost resistance of foam concrete. The pore structure of foam concrete is improved obviously by polypropylene fiber. Due to the uniformly distributed pores, high porosity and rather complete pore wall, the mechanical properties and thermal properties of foam concrete are excellent. The foam concrete with high-strength and excellent thermal insulation property develops a new route for the comprehensive utilization of iron tailings.

Abstract: Strength properties and modulus characteristics were studied through laboratory experiment with different gradation types, different cement content of cement stabilized macadam. Test results show that, in the same conditions of aggregate types, the two important factors that influence cement stabilized macadam road performances are mixture types and cement content. With the improvement of the amount of cement, the mixture strength and modulus of resilience are growing; when we use a certain amount of cement, different types of cement gravel structure show different properties. And frame cement stabilized aggregate exhibit excellent road performance.

Abstract: In consider of construction characteristics of drilling bitten pile in Kunming metro engineering, this paper study on preparation and performance of super retarded concrete. Meanwhile, this paper find appropriate raw materials and mixing amount, which can meet construction requirement of high flowability and long setting time for this engineering. Combined theory with experiments, it lay the foundation of popularization and application of super retarded concrete to find the influence law of performance of super retarded concrete by mixing amount of all materials.

Abstract: To know the pore structure of cement-asphalt pastes, mercury intrusion porosimetry was applied to measure the total porosity, pore distribution and accumulative volume distribution of pore size and the pore structures were analyzed. The results show that the total porosities decline with increase in ages and reduction in A/C ratio. The total porosities declines from 28% at 1d, to 15.8%~17.2% at 28d; the most probable pore size declines from 20nm at 1d to 5nm at 28d.At 28d, there is an increase in the magnitude of pore size between100nm and 5μm; the volume faction of smaller than 5μm is 40~50%; and the amount of pore size smaller than 5nm account for 6%.There are two peaks (5μm & 50μm) in the curves of pore distribution.

Abstract: This paper deals with the experimental measurements and computer analysis of the development of heat of hydratation and shrinkage in a large-scale model of a reinforced concrete slab. A large-scale model was built in situ to experimentally verify the design of the reinforcement, with the aim of preventing the formation of cracks in slab. The model represents a four times four meters cut of a slab structure of a thickness of 1.6 m. Bars in the horizontal direction of the slab were extended behind the concrete body and welded to a steel frame, which simulated the anchorage of horizontal reinforcement of a continuous slab. Before casting, the reinforcement bars were fitted with vibrating wire strain gauges and with resistance gauges for monitoring the strain, as well as with temperature sensors for determining the temperature field caused by heat of hydration. According to the needs of the experiment, the structure was modelled in GiD 11.0 software and calculated in the AtenaWin program. The experimental results and the results obtained by a numerical analysis were compared.

Abstract: This paper deals with the experimental measurements and computer analysis of the development of heat of hydration and shrinkage in a large-scale model of a reinforced concrete wall with a base slab. A large-scale model was built in situ to experimentally verify the design of the reinforcement, with the aim of preventing the formation of cracks in a long massive wall located on a base slab. The model represents a four meter cut of a long wall structure (thickness of 1.6 m) together with its base slab (thickness of 1 m). Bars in the longitudinal direction of the wall and of the base slab were extended behind the concrete body and welded to a steel frame, which simulated an anchorage of longitudinal reinforcement of a continuous wall with a base slab. Before casting, the reinforcement bars were equipped with vibrating wire strain gauges and resistance gauges for monitoring the strain, as well as with temperature sensors for determining the temperature field caused by heat of hydration. According to the needs of the experiment, the structure was modelled in GiD 11.0 software and calculated in the AtenaWin program. The results of the experiment and the numerical analysis were mutually compared.

Abstract: Modern tall buildings are more flexible so occur excessive wind-induced vibration resulting in occupant discomfort and structural safety. Many studies to reduce such a wind-induced vibration using a feedback controller and auxiliary devices have been conducted .The optimal control law of linear quadratic Gaussian (LQG) controller is used for reducing the across-wind vibration response of a tall building with an active mass damper (AMD). Fluctuating across-wind load treated as a Gaussian white noise process is simulated numerically in time domain. And using this simulated across-wind load estimated across-wind vibration responses of tall building with AMD using LQG controller.