Advanced Materials Research Vols. 1004-1005

Abstract: 5% cement was mixed into the cement stabilized macadam base material, then the cement was replaced by SES-I early strength admixture according to the amount of cement (mass ration) which was 0%, 8%, 10%, 12%, 14% and 16%. The unconfined compressive strength R_c of cement stabilized macadam material was tested during different curing periods 12h, 1d, 2d, 3d, 7d and 28d. Depending on the experimental date, the effect of early strength admixture on cement stabilized macadam material was investigated, and the logarithmic curve relationship can be fitted between the SES-I admixture and R_c. The experiment result shows that the 14% dosage of early strength agent is the best result for material early strength, and it also provides the foundation to increase early strength and shorten the construction period for meeting the project design demand.

Abstract: In order to study the influence of natural rock asphalt on the temperature susceptibility of matrix asphalt, the effect of matrix asphalt modified with different dosage natural asphalt was analyzed by penetration index and viscosity temperature index. Research results show that the PI value and softening point of modified asphalt grow with increase of natural asphalt dosage, however viscosity temperature index (VTS) decreases gradually, which indicate that modified asphalt is less influenced by temperature. Namely, the temperature susceptibility is improved, and the improvement effect changes with the increase of natural asphalt dosage.

Abstract: Silica fume (SF) modifies interfacial transition zone between cement paste and aggregate at the micro level. Properties of both fresh and hardened silica fume concrete are affected significantly compared to normal concrete. Experiments indicate that concretes become more cohesive and less prone to segregation in the presence of silica fume, moreover, performance of water demand, setting of time, plastic shrinkage varies respectively from concretes without silica fume. Obvious mechanical enhancement of concrete is observed in the aspects of compressive strength tensile strength, elastic modulus as well as fracture toughness.

Abstract: Less than half a century ago just an idea of presence of free alkalis in a ceramic matrix was considered by ordinary Portland cement people as an absurd one and this was a basic postulate accepted in chemistry of cements. In 1957 a scientist from Ukraine (USSR) Viktor Glukhovsky put forward an assumption which was taken as a base for development and bringing into practice of construction a principally new class of cementitious materials which first appeared in the field under a name of alkaline (now also known under a general name of alkali-activated) cementitious materials. A validity of these ideas was confirmed by more than 50 years of evolutional development and vast experience collected on practical use of new materials in different applications. The paper covers theoretical views on role played by alkali in the formation of an alkali-activated cement matrix with high durability. Examples of compositional build-up of the alkali-activated cementitious materials vs. quantity of added alkali and type of aluminosilicate component are reported together with results of 50-year experience obtained from observation of concrete structures made from these cements.

Abstract: Compressive experiments on mortar-free grouted concrete masonry composed with hollow blocks were studies in this essay. Characteristics of compressive stress-strain curve were analyzed by utilizing test data of 15 specimens with 100% filling rate of grouted concrete. Further more, elastic modulus formula was proposed according to results of previous and present work.

Abstract: The bridge tower crack extension probability is very large because of the stress concentration at the crack tip, combined with the fatigue stress. Based on the long-term observations of temperature fatigue load spectrums of a bridge tower and the experiment of concrete fatigue performance parameters, the problem of crack propagation is analyzed by infinite life safety reliability model and safe and reliable crack extension randomness model. It is concluded that the concrete structure crack extension probability is close to 98.6% and reasonable repair cycle should be about 3 years.

Abstract: The stability analysis and evaluation is the base of the landslide prevention, at the same time have improvement guidance to the landslide prediction. Divided the Chinese landslide stability analysis of research history into three stages:①experience analysis and evaluation stage;②half experience and semi theoretical analysis and evaluation stage;③theoretical development and the deeping stage. Described the research situation,trend and existing problems of the slide stability analysis and evaluation,get a clear conclusion,put forward my own understanding.

Abstract: At present, China's economy is developing rapidly, urbanization level enhances increasingly, the energy consumption and environmental pollution problems are getting serious increasingly, and it is deviating from the concept of sustainable development. Green building is an important way to achieve the concept of sustainable development and green building assessment system is the important basis and key to its development. Through the comparative study on evaluation methods and objects of the main evaluation system in China and abroad, this article find out the deficiency of the evaluation system in our country, draw lessons from foreign assessment system, and make our country green building assessment system more perfect.

Abstract: The correlation of chloride diffusion coefficient and concrete maturity value within 56 days of curing was investigated by the chemically combined water content method, rapid chloride migration (RCM) test and concrete maturity test, respectively. The experimental results showed the chloride diffusion coefficient of concretes decreased not only with increasing curing ages, but also with increasing curing temperature, which can promote the hydration degree of cementitous. There is a significant correlation between the chloride diffusion coefficient of indoor curing specimens and the concrete maturity value when expressed as a power function (R²=0.976), and the calculated values of concrete maturity for outdoor specimens which obtained by using the power function agrees well with the measured values, then it can use the measured concrete maturity value to predict the chloride diffusion coefficient of concrete. And then in this project, when the immersed tube tunnels were placed in seawater, the recommended value and the control value of concrete maturity was 21064°C•h and 13926°C•h, respectively. Furthermore, the ages of the tunnels placed in seawater can be appropriately adjusted by calculation when considering the external curing temperature and heat of hydration of cementious.

Abstract: Doors and windows,especially the exterior windows, are the weak parts to preserve or insulate heat in the exterior protected construction of a building, and the main contents in energy-saving architectural designs. The energy-saving design of exterior windows should start from such aspects as size, shape, frame form, glass type, gap sealing, etc. The size of the exterior window holes should be determined according to the window-wall area ratio specified in the relevant rules. It is priority to choose side-hung window in energy-saving design, to choose the low heat transferring window frame, to take measures to break the “thermal bridge”, and to select the energy-saving glass such as decalescence glass, coated glass, hollow glass and vacuum glass. The gaps should be sealed tightly between wall and window frame, window frame and sash, glass and window sash to reduce the air permeable.