Advanced Materials Research Vols. 450-451

Abstract: A new interaction integral technique is derived for computation of mixed-mode stress intensity factors (SIFs) in nonhomogeneous materials with continuous or discontinuous properties. This method is based on a conservation integral that relies on two admissible mechanical states (actual and auxiliary fields). In the equivalent domain formulation, the integrand does not involve any derivatives of material properties. Moreover, the formulation is proved to be still valid when the integral domain contains material interfaces. Therefore, its applicable range is greatly enlarged. The method is combined with the extended finite element method (XFEM) to calculate the SIFs for different integral domains. Numerical results show that the interaction integral has excellent convergence for material nonhomogeneity and discontinuity.

Abstract: Foam concrete aggregates and inclusions have greater strength, but the pore almost has no compression resistance; hydrated cements and pores are the weak links in the pressure cross-section of the foam concrete. As for unit volume of foam concrete, cement accounts for a large space and the pore occupies less, so the block intensity will be larger. Considering mechanical properties of the aggregates and hydrous cements are different, the volume ratio of hydrous cements to the sum of cements and pores is used to build the strength model of foam concrete, which can be simple and feasible. It can response the foam concrete strength characteristics more accurately.

Abstract: Floor area ratio (FAR) is fundamentally important for urban economic development and for urban design, planning and management. This paper tried to enhance the texture information of the QuickBird image by using HIS and PCA transform methods in Yiwu city as a case study. An object-based method was proposed to process the enhanced QuickBird image for the shadow of buildings and building object areas, and the building heights were accurately calculated based on the shadow of buildings. The building object areas and heights were integrated with an administrative district map in Yiwu city to estimate FAR. Tests with this above method demonstrated excellent accuracy in terms of FAR estimation. The high spatial resolution images have great potential in quickly and accurately estimating FAR, providing a scientific basis to policy makers and urban planners.

Abstract: Rock wool and slag wool pertain to the same kind of thermal insulation material, which can be produced in quantity and widely used, by comparison with other inorganic fiber thermal insulation materials, thus it is one of the most important thermal insulation material for the national economic development in our country. After the implementation of Civil Construction Energy Efficiency Management Regulation, it puts forward higher requirements for the energy saving standard of new buildings, thus the application prospect of rock-mineral wool thermal insulation material is promising. This paper mainly presents the source of rock-mineral wool, its main relative merits as well as its application in the construction field, moreover, the application and development potential of rock-mineral wool as the thermal insulation material for building wall construction.

Abstract: This paper analyzes driving factors that caused Nanluogu Lane to change based on the research on the spot, discusses reasonability and sustainability of the changes, and proposes some initial reconstruction ideas while taking courtyard as its research object and meeting people's basic needs.

Abstract: This paper discusses the particle packing background of cementitious materials. On micro-level the Portland cement and eventually the mineral admixture grains can be considered packed in the watery environment. Particularly for (super) high performance materials, the packing density can be quite significant. An economic and due to fast computer developments reliable way to study packing of the binder, is by modern discrete element modeling (DEM) approach. In this paper use is made of a concurrent algorithm-based dynamic system, HADES. Hydration is simulated based on spherical grains. Thereupon strength can be studied on the basis of packing density. For durability issues, the complex and tortuous 3D pore structure has to be investigated. This paper uses for the assessment of pore characteristics the robotics-inspired DraMuTS system. Hydrated Portland cement is compared with gap-graded rice husk ash-(RHA)-blended (green) Portland cement. Experiments on gap-graded RHA-blended PC concrete are used as reference. Packing density is shown improved by gap-graded packing. What is more spectacular are the effects of gap-grading with RHA on the pore characteristics obtained on the DEM-produced virtual materials. This paper discusses the expected positive effects on transport-based durability issues due to gap-graded packing-induced changes in the pore system

Abstract: Using recycled fine aggregate in the practical engineering provides waste concrete a sustainable utilization road and the cracking property of recycled fine aggregate concrete immediately influence the service life of concrete. The paper consults ICBO standard, carries out stationary plate method and it puts importance on the influences on the concrete, the particle size, the replacement rate of recycled fine aggregate and mineral mixes. The result indicates that the fine particles between 0 and 0.15mm are not good for the crack resistance of recycled concrete. The replacement rate of recycled fine aggregate should be controlled less than 50%. Adding a certain amount of fly ash could enhance to some extent the crack resistance of recycled fine aggregate concrete. But the plastic cracking risk of recycled fine aggregate concrete increases because of the adding silica fume.

Abstract: Mathematical modeling is a mathematical thinking method, is using the mathematical language and means, through the abstract, simplified can approximate solution actual problem a powerful mathematical method. In this paper, according to the teaching of the specific example analyzed of mathematical modeling of understanding, base the teaching material, mathematical modeling process, strengthen the revealing of mathematical modeling consciousness training, improve the ability of mathematical modeling. Mathematical modeling thought and method of the seepage, must be run through the teaching process throughout, must have the plan, a step-by-step and destination permeates gradually.

Abstract: In order to improve the concrete performance and research the greenmaterial, the recycled ABS/PC plastic particles will be added into the cement concrete as a modifier. In this research, the C30 cement concrete was taken as the basic material, the fine aggregate in cement concrete was substituted by different amounts of recycled plastic particles. The change law of mechanical performance indexes（including cubic compressive strength. Splitting tensile strength，bending strength）were researched. The research result showed the recycled plastic particles, as a modifier, can improve mechanical performance of the cement concrete greatly. In the five addition amounts，including 0%, 2%, 5%, 8%, 11%，the three mechanical strengths will all increases at first then decreases with the addition amount increasing. When the addition amount is 5%, the three mechanical strength indexes will all reach the maximum.

Abstract: Concrete has one of the highest carbon footprints of building materials in use, and is also one of the most often used building materials in modern construction. Polystyrene is a non-biodegradable polymer in continued use. This paper examines the feasibility of using polystyrene beads in structural concrete. Recycled polystyrene beads were used as a coarse aggregate in concrete mixtures to explore possible structural application. Two samples apiece of three experimental mixes of concrete as well as control concrete mixtures were tested in the laboratory for density and compressive strength at 14, 28, 56 and 70 days curing. The laboratory testing showed one experimental mixture was of comparable compressive strength to the control concrete mixture. The experimental results demonstrated that recycled polystyrene concrete in volumetric percentages below 18.75% could be a feasible green concrete mixture.