Advanced Materials Research Vols. 919-921

Abstract: Ground-Source Heat Pump (PSHP) was verified by US Environmental Protection Agency (EPA) as one of the most efficient air conditioning systems on present market. It has a higher efficiency than other heating systems from 50% to 70%, and a higher efficiency than other cooling systems from 30% to 50%. The working principle of PSHP determines its low operating costs. By comparing the total energy efficiency, the existing groundwater heat pump total energy efficiency is the highest, about 115%. The total energy efficiency for soil-source heat pump is up to 100%. But traditional air conditioning is far less than the level. Articles present a research on Ground-Source Heat Pump system and its cost with a scientific and objective principles. Ground-source heat pump is a new central air conditioning system of Low-carbon energy saving. Due to the high technical content, function requirement, and installation difficulty , the average initial investment of ground-source heat pump is much higher than traditional central air conditioning. Taking into account the added costs of heating systems based on traditional central air-conditioning, such as boilers, it will not deviate too much from it.

Abstract: The energy-saving management system of major projects in implementation has always been in a state of imperfect. On the basis of combining energy-saving management status of major projects in implementation, referring to the research results of the management mechanism design theory at home and abroad, this paper aims at the primary interest-related subjects of the major projects energy-saving, uses economic mechanism designing theory and incentive theory, designs the energy-saving management mechanism; It does the theoretical analysis of the government and major projects owner with the complete information dynamic game model, then, provides decision evidence for the government to formulate the rational management intensity and maximize the interests of all parties. At last, the paper provides the suggestions to solve the existing problems of major projects energy-saving management.

Abstract: There are often people and goods in and out of the dinning room door, so the door is often open. Heating and air conditioning construction to save energy and to prevent the outdoor air form influencing on indoor environment, set up the air curtain at the entrance of the dinning room to stop outdoor air, the frequently-used air curtain is beam type of air curtain.The project in view of the dinning room of the new campus of hebei university of science and technology, sets up air curtain physical model of the ground floor dining room door at the first area, and carry on reasonable simplification, make sure the numerical simulation calculation area and the sealing condition of air curtain. Then set up physical model for wind pressure, multiply of hot pressure and the local hot pressure at the dinning room door of the air curtain air flow in CFD method. Through the numerical simulation for different jet velocity of the hot air curtain, analysis the temperature field, velocity field, heat loss,heat load parameter, etc. and demonstrate the energy saving effect, and provide reference basis for the selection of air curtain.

Abstract: The mal-condition of environment directly affects the durability of concrete, and which has become a widespread problem under the complicated environment conditions. Domestic and overseas scholars have carried out many researches on the durability of concreteunder different environmental conditions. The mass and the dynamic elastic modulus loss are focused as two major criteria in the evaluation of concrete damage. The article further gives researches on the durability of concrete in the saline soil environment in the west region of Jilin province. The concrete durability tests are conducted under the actions of salt soaking, salt corrosion and freezing-thawing cycles, and salt corrosion and dry-wet cycles. Comparing the test results in the same coordinate system, it is concluded that the dynamic elastic modulus of concrete can reflect the degradation process of concrete performance more accurately and intuitively, and forecast the failure behavior of concrete under the action of various environmental factors timely and effectively. Therefore it can be used as the main index for no damage detection, while the mass loss can be acted as the auxiliary detection index during the concrete durability tests.

Abstract: An in depth state-of-art review is done on the topic, constitutive relations of masonry under compression. 12 constitutive models of masonry proposed by scholars from home and abroad are presented in the paper. These models can be classified into four types. Merits and drawbacks of each constitutive relation are discussed. Ten typical constitutive relations are selected to make comparisons. Results show that the ascending branch of curves has few differences, major differences occur in the descending branch of curves. Besides, two experimental data are used to analyze the models and results are discussed. Furthermore, some suggestions on this topic in future research are presented.

Abstract: This study experimentally investigated corrosion-induced deterioration in reinforced concrete (RC) structures: concrete cover cracking, steel-concrete bond loss, and mechanical degradation of corroded steel bars. Pullout and RC beam specimens were prepared, subjected to accelerated corrosion in a wet sand bath, and tested under loading. A 3D laser scan was employed to measure the surface profile of corroded steel bars and determine the corrosion effect on the distribution of residual cross section area. The crack width on the concrete surface was sampled randomly and analyzed statistically. Corrosion reduced the bond strength between steel bars and concrete, particularly in the form of corrosion-induced number and width of cracks. Both the yield and ultimate strengths depended upon the critical cross sectional area of steel bars, whereas the elongation changed with the cross section distribution over the length of the steel bars. Corrosion also changed the distribution of the cross sectional area of steel bars. The crack width on the concrete surface can be well represented by a normal distribution regardless of corrosion levels.

Abstract: Coal and biomass are pyrolyzed to get gaseous fuels (CO, H₂ and CH₄), carbon aggregates, and useful Ca-species for the preparation of carbon building materials. By using hot-extrusion of carbon powder with coal-tar-pitch at temperatures above 400^oC, the sample can be densified to have good strength and the potential for structure application. Two coal samples and four biomasses have been investigated and so to depict the feasibility of the application of HECBM.

Abstract: The mechanical properties of PHC pile concrete with different mineral admixture (fly ashground slagground silica sand) were tested and interface microstructure of the concrete were analyzed by ESEM.The result show that,the compressive strength of PHC pile concrete with 20% ground silica sand or with 30% ground slag can reach more than 80MPa after autoclaved curing;The PHC pile concrete with 20% ground silica sand show the best mechanical properties.The tobermorite C₅S₆H₅ can be observed in ESEM photograph of interface of autoclaved curing concrete.

Abstract: Lithium-based chemicals are known to their signal effect on restraining alkali-silica reaction but uncertain influence on workability and mechanical property in the concrete. The aim of this research is to analyze the effects of three lithium additiveslithium nitrate (LiNO₃), lithium hydroxide (LiOH) and lithium carbonate (Li₂CO₃) at various dosages, with an extensive comparison on fluidities, setting times and compressive strength of cement pastes. The experimental study shows that test results vary with the type of admixture. In general, three conclusions can be made: 1) lithium nitrate and lithium hydroxide can enhance the fluidity of cement paste, but lithium carbonate has opposite effects; 2) all three lithium salts shorten setting time as well as decrease the strength at suitable dosages; 3) the variations in lithium additives dosages have different influence on the cement pastes setting time and compressive strength development.

Abstract: Experiment on the compressive strength and splitting tensile strength of fiber lightweight aggregate concrete (FLWAC) after freeze-thaw cycling and high temperature was tested through blending polyvinyl alcohol fiber (PVAF) and polyacrylonitrile fiber (PANF) in aggregate concrete respectively. Five temperature levels, room temperature, 200°C, 400°C, 600°Cand 800°C were selected to heat the FLWAC test blocks after 25 times of freeze-thaw cycling. The micro-structure of FLWAC was observed through SEM. The experiment results show that, the cubic compressive strength of FLWAC is improved when the temperature is above 200°C, and the splitting tensile strength of FLWAC is obviously improved between the ranges from room temperature to 600°C. Blending fiber can weaken the brittle fracture performance of LWAC after freeze-thaw cycling at the peak loading state. However, the mass loss doesn’t have obvious improvement before and after 25 number of freeze-thaw cycling.