Applied Mechanics and Materials Vols. 638-640

Abstract: The current asphalt binder specifications in Libya are based on the Penetration Grade: penetration test is performed at 25°C. Penetration is an empirical measure of the consistency that is used as an empirical indicator of the rutting and fatigue susceptibility of asphalt binder, and is not related to pavement performance. The new mix design methodology developed under the Strategic Highway Research Program (SHRP), called the SUPERPAVE is a performance-based approach. The first step in the implementation of SUPERPAVE methodology is to establish high and low pavement temperatures for a location. The temperatures define the required Performance Grade (PG) of asphalt binder. This paper documents the initial ground work towards implementation of SUPERPAVE mix design for establishing high and low geographical temperature zones. The temperature zoning of Libya was carried out by using temperature data obtained from 8 weather stations. The SHRP and LTPP prediction models were utilized for predicting pavement temperatures. A significant difference was observed between the predicted pavement temperatures from both the models. The SHRP model gives higher, high temperature PG grade providing additional protection against rutting. Since rutting is the most common distress on flexible pavements in Libya , the SHRP models at 50% level of reliability is recommended. The PG of roads that located in Libyan desert are classified to three zones (PG70-10, PG76-10 and PG82-10.PG 76-10 binder seems to be the most common grade that encompasses more than 70% area of Libya desert .However, currently none of the two local refineries produce the bitumen under penetration grade 60-70,that grade equivalent to PG 82-10 binder, thus it should be a concern for highway or the project location. The polymer modified asphalt binder are not produced by Libya refineries.

Abstract: Calcium formate and superfine powders comprised of fly ash, slag and silica fume have been used as raw marerials in this research. The results showed that when superfines powders were mixed with 1.5% calcium formate in a fixed porpotion, the 1 day and 28 day compressive strength of concrete can increase 133.7% and 115.9%, respectively.

Abstract: The performance of resistance to sulfate attack and permeability of chloride ion on concrete with different mineral admixtures (fly ash, slag single or both adding) under sulfate and chloride environment were discussed. The results indicated the performance of resistance to salt attack on concrete with appropriate mineral admixtures was improved. Under chloride environment, the resistance to sulfate attack coefficient of testing mortars descended, and compressive strength loss rate of concrete was raised after dry-wet cycles. Therefore, the performance of resistance to salt attack on concrete was decreased in this environment. Besides, on the initial stage of corrosion, the ability to resist chloride ion penetration of concrete was improved under sulfate environment, while the penetrating of chloride ion was accelerated on the later stage.

Abstract: When the concrete is in the process of load, the curve of amplitude - frequency shows significant characteristic of exponential. As the load increases, the acoustic emission signals gradually become complete, the more obvious features of this exponential function. Using the least squares method, we can get an empirical function expression by fitting the data.Function expression has different regression coefficients in different load stages, and regression coefficients changing with load also presents certain rules, which has a good indication to qualitative process of structural damage.

Abstract: Preparation of carbon nanotubes from the controllable flame is a kind of new method. Experimental apparatus is including controllable flame burner, temperature measuring instrument, mass flow meter and catalyst preparation system, etc. The sampling substrate is the growth platform of carbon nanotubes in the flame. The type316 stainless steel is selected as sampling substrate in the experiment. Carbon monoxide provides carbon source and hydrogen/helium premixed gas acts as protection gas. Characterization of the carbon nanotubes on the stainless steel substrate from the controllable flame is by scanning electron microscope (SEM) and transmission electron microscope (TEM). It was found in the experimental that the iron-based catalyst particles are mainly distributed in the ends of the carbon nanotubes. The experimental results reveal that the growth of carbon nanotubes will be very exuberant if the sampling time is controlled within ten minutes.

Abstract: To investigate progressive collapse behavior of reinforced concrete (RC) flat plate structures, a reliable and efficient numerical approach is developed in this study using spring connection modelling. This connection unit aims to simulate complicate punching shear behavior at critical regions surrounding the columns. Five springs are used as the connection elements: two for flexural and integrity steel bars and three for concrete contributions. The flexural and integrity steel bars embedded in the columns are modeled explicitly, which enables the model to present the structural behavior post punching shear failure. Bending and shear actions are represented by two concrete springs. The third concrete spring is assigned axial action property to restrain two end nodes of the connection on the model. In particular, the punching shear spring controls the connection unit when punching shear failure occurs. To apply the connection unit, the regions of slab-column connections are partitioned from the slab regions according to the critical shear surfaces. Then the connection unit links two corresponding nodes on the two edges formed from the partition. A physical experiment of a RC flat plate substructure under progressive collapse is simulated. Result comparison demonstrates that the numerical model has the capability to capture the structural behavior in progressive collapse. However, further improvement of the modelling technique is necessary to enhance numerical accuracy.

Abstract: Modern villas in East and West Valleys of Mount Lu have witnessed the importance of Mount Lu in Chinese modern history, their unique design and elegant environment have high historical value and artistic value,and they are iconic landscapes in Mount Lu scenic area. In this paper, Mount Lu villas are the main research object, types of construction material and key use were analyzed. "Stone villas give Mount Lu personality", the author revealed unique building materials and obvious construction features of Mount Lu villas, which offered a systematic theoretical basis for protection, restoration and reconstruction of modern villas in Mount Lu.

Abstract: Over-sulfur phosphogypsum(PG)–ground granulate blast-furnace slag(GGBFS) cement paste is utilized by GGBFS, Portland cement clinker(PCC), additive, water and modificated phosphogypsum paste(MPG), produced by milling PG mixed with a certain proportion of steel slag(SS), GGBFS and water. The effect of PG on the properties of over-sulfur PG– GGBFS cement was investigated. The mechanical performances and hydration mechanism of the cement with different kinds, proportions and particle size of PG were analyzed based on setting time, volume stability, strength test, XRD and SEM analyses. The experimental results show that,the optimum mixture of PG amount in the binder was 45%. Overdose of PG may caused strength deterioration. The optimum grinding time of MPG in the binder was 20min. The soluble phosphorus content of PG in the binder was under 0.05%.

Abstract: This article uses hydroxylethyl acrylate and phosphorylation reagent for esterification reaction, synthesis of a phosphate ester monomer with double bonds, and phosphate ester monomer ,Participation as the third monomer polymerization of acrylic acid and isoprene polyoxyethylene ether (TPEG). Polycarboxylate was synthesized with phosphoric acid ester structure,Investigate the impact of Phosphate ester content in single and double to polycarboxylate performance. The results showed that the polycarboxylate with phosphate structure has excellent adaptability and reduction of water slump performance.

Abstract: In this article through grinding colorless waste glasses respectively 1,2,3,4,5,6,7,8,10,20,30 min, then calculate the fineness modulus and fractal dimension of waste glass powder, it is concluded that with the extension of grinding time the fineness modulus of the waste glass powder show the trend of decreasing first then increasing and decreasing again in last,and it is mainly decided by the cumulative sieve residual value of different particle size.The fractal dimension of waste glass powder show the trend of increasing first then decreasing and increasing again in last, and it is mainly decided by the particle size,surface morphology and structure loose degree of the waste glass powder.