In order to evaluate the particle breakage percentage and improve fundamental understanding of particle-based mixture construction, this paper presents the laboratory testing results of mineral aggregate mix compaction. In this research, the laboratory compaction tests were conducted under heavy compaction. In preparing the testing samples, aggregate gradations, water contents, and aggregate types were considered. After compaction, CBR (California Bearing Ratio) values optimum moisture contents (OMC) or moisture content (MC) and maximum dry density (MDD) were measured. In order to quantify the particle break percentage, the compacted samples were sieved and analyzed. Furthermore after compaction the changes in gradations could be determined. Through laboratory testing results, connections with design moisture content (DMC) and actual forming moisture content (AFMC) and particle breakage with CBR (California Bearing Ratio) values were established. Besides relationship between design water content and forming water content was cubic function and proctor compaction had a great influence on gradations, particles especially coarse particles reduced a lot while fineness modulus seemed to increase and there was an optimum crushing value under which CBR reached maximum.
Abstract Geological slopes are often disturbed by external engineering, leading changes of the upper moisture content and dry density in loess-mudstone composite layer. It directly affects the shear strength of the loess-mudstone composite layer interface. In order to explore the influence of the upper loess moisture content and dry density on the shear strength of the loess-mudstone composite layer, taking the cutting slope in a test base in Shaanxi Province as the engineering background, different loess moisture contents (10%, 13%, 16%, 19%) and dry densities (1.4, 1.45, 1.5, 1.55 g/cm 3 ) are employed to investigate the shear strength of loess-mudstone composite layers. Scanning electron microscopy (SEM) is used to observe the failure interface of the loess-mudstone composite layer to analyze the failure mechanism of the samples. The results show that: (1) The shear strength of the loess-mudstone composite layer is lower than those of pure loess and mudstone samples. (2) The moisture content of loess will deteriorate the shear strength of the composite layer, and its effect is greater than that of homogeneous loess; but the dry density of loess will enhance the shear strength of the composite layer, and its effect is less than that of homogeneous loess (3) The moisture content and dry density of loess will affect the distribution of pores in the composite layer interface, changing the shear strength of the composite layer. The research can provide certain data and theoretical basis for the prevention and control of landslides at the loess-mudstone interface.
The Mouse-Erythrocyte-Micronucleus (Mus-EMN) assay is a modified mouse-micronucleus test which conventionally scom the micronucleus frequencies in bone marrow polychromatic etythrocyies (PCE). In the Mus-EMN assay, MN frequency is scored in mature normachromatic erythrocytes (NCE) in the circulating blood obtained fmm the tail or the eye socket of the mouse. This simplifd in vivo Mus-EMN assay was used to monitor the chronic clastogenicity of industrial wastewater throughout one year in the cumt study. Twenty four young (2 month old) CDl white mice were divided into 3 groups of 8, with 4 males and 4 females in each group, and caged individually for this study. Two treated groups of animals were fed with industrial wastewater cdlected weekly fmm the down stm of the Arena Canal (wastewater dispoal system) from the Benito Juarez Industrial District of the Queretaro Ciiy of Mexico. In order to reduce the toxicity, wastewater samples were diluted with tapwater at 1:s ratio (wastewater: tapwater) for treated group 1 and a 1:2 ratio fortreated group 2. Animals of the control group drank the tapwater. Red blood samples were collected monthlyfrom the tail and blood smears were double stained with hernatoxylin and Giemsa, and about 10,000 mature red blood cells were scored from each of the 8 slides of the experimental groups to derive the means and standard emrs. Results of this year-mund study showed a significant increase in MN frequencies (5.08 - 9.80 MN11000 cells) in the treated groups during the months of Octuber through January of the following year, the dry season of this area of Mexico. The MN frequencies of the treated mice declined to the control level (1.29 - 3.20 MN/1000 cells) afier 6-7 months of continuous exposure. Results of this study indicate that the Mus-EMN assay is adequate for chronic clastogenicity tests of water pollutants with the maximum time limit around 6 months which is abwt 20% of the youthful life of the mouse.
The grain size of aggregate particles is crucial to the mixture gradation of discrete-element (DE) models when realistic aggregate shapes are simulated. The objective of this study was to answer the question of how to determine the grain size of aggregates using DE models based on virtual sieving analysis. First, virtual sieving analysis models were developed with prolate ellipsoid, oblate ellipsoid, and cubic-shaped particles, and virtual sieving was performed under three vibration patterns, namely, vertical, horizontal, and hybrid vibration. The influence and efficiency of the vibration patterns were analyzed based on the results of the virtual sieving analysis. Then, the virtual sieving analysis was conducted with realistic aggregate shapes. By analyzing the test results, the shape sieving factor (Ssf) was derived and was used to calculate the grain size of individual particles. For further validation, the grain size (Gs) of selected aggregates was measured by lab manual measurement and virtual sieving analysis, separately. Then the test results were analyzed and compared. The main findings from this study include the following: (1) vibration patterns had significant impacts on the results of the virtual sieving analysis, and vertical vibration is recommended for virtual sieving analysis; (2) particle shapes had important impacts on the results of the virtual sieving analysis, and it was determined that aggregates with cubic shapes are relatively difficult to pass through the sieve meshes; (3) most particles can pass through smaller sieve apertures than their equivalent-volume spheres; (4) the approach to virtual sieving analysis developed in this study was validated by lab sieving tests, and the shape sieving factor (Ssf) derived from the virtual sieving analysis can be used to generate DE models with more accurate gradation.
With the continuous development of bridge construction in the direction of rapid speed, high quality and environmental protection, prefabrication technology has become the mainstream trend of bridge engineering development.Based on the prefabricated T-beam construction of the smart girder fabrication yard of the Hangzhou-Shaoxing-Ningbo Expressway Project, it was proposed a "mobile pedestal + hydraulic formwork+ steam curing + two-stage tensioning" assembly line construction process.Advanced technologies such as intelligent mobile pedestal, fully-enclosed high-temperature steam curing and Building Information Modeling were utilized to achieve the intelligence of Tbeam prefabrication production through smart equipment, standardized process and intelligent management.The result demonstrates that the new technology of prefabricated assembly line construction significantly reduces the production cycle and enhances the quality of prefabrication when compared to traditional construction methods.
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