Experimental Study on Previous Concrete with Various Mix Ratios

The pervious concrete is designed with cementitious material content just enough to coat the coarse aggregate particles so that a configuration that allows the passage of water at a much higher rate than conventional concrete. The pervious concrete has many advantages that improves city environment, recharges the ground by rain water and could be used as pavement for light vehicles, pedestrian pathways, parking lots, also it reduces the tire pavement interaction noise etc. In this paper, structural property and permeability of pervious concrete made without and with different ratios of fine aggregate and pozzolan. 9.5 mm maximum size of crushed gravel and constant aggregate/cement ratio of 3.6 were used. Mix design void content is tested 20%. The specific gravity of fine aggregate 2.53 and the specific gravity of crushed stone 2.56. Type I Portland cement and water- reducing and retarding concrete admixture were used. Mix design is based on the no slump method from the American Concrete Institute’s Committee 211.3R-02, “Standard Practice for Selecting Proportions for No Slump Concrete.” This research work was divided into third/three sections. The first section is without pozzolan and fine aggregate and second section is with two different ratios of pozzolan third section is without pozzolan and with fine aggregate. Pozzolan is used as a supplementary cementitious material to partially replace Portland cement in pervious concrete mixes up to 20% by weight. Fine aggregate partially replace as a coarse aggregate in pervious concrete mixes up to 10% by weight. Mix design void content is tested 20%. This concrete is tested for its properties, such as density, void content, compressive strength and water permeability. The most important property of pervious concrete is its water permeability

Study on Rust Characterization and Prediction of Atmospheric Corrosion Rates for Structural Steels in Yangon (Myanmar)

According to Fontana, “Corrosion is defined as the deterioration of a material because of reaction with its environment”. The present study is performed to get the behaviour of rust characterization and to predict long term atmospheric corrosion rates of structural steels in Yangon, Myanmar. Three types of structural steel (Type A, Type B and Type C) samples which are commonly used in Myanmar are exposed outdoors according to BS EN ISO 8565. They are removed one month periods, and their mass losses are determined according to ISO 8407 in Yangon Technological University. At the same time, environmental parameters of the test site are monitored. Rust characterization of structural steels is determined by Scanning Electron Microscopy (SEM) results in University Research Centre (Yangon University, Myanmar). From SEM results, Type A and Type B steels have nearly the same image controlled by β-FeOOH which can increase long term corrosion, whereas Type C steel has controlled by γ-FeOOH. A prediction model is developed using SPSS software to understand the main factors which cause the atmospheric corrosion, and it is found that the atmospheric corrosion in Yangon depends mainly on the time of wetness (TO

Influence of Surcharge Loading, Retained Soil and Restrained Soil on Design of Diaphragm Wall

Many different types of embedded retaining wall are constructed due to the increasing demands. In Yangon, Myanmar is encountered deep excavation problem. Many buildings are damaged due to excavation of adjacent building. Therefore, embedded retaining wall as excavation support system is necessary to be sustainable buildings. There are important that influence of surcharge loading, retained soil and restrained soil on design of embedded retaining wall.  In this paper, diaphragm Wall is emphasized and solved using soil structure interaction analysis. Behaviour of diaphragm Wall wall is based on various factors. Consider with natural and increasing of shear strength parameter of retained and restrained soils to get the level of the dredge line is stiff soil and various distances from wall to surcharge. Sites are located in urban setting, there are near building and separately from main structure. This project involves the construction of 5 m depth retaining wall. In case study (A) retained soils is soft, medium (low) clay, restrained soil is mostly cohesive soil. There are medium (low), stiff, medium, hard soil layers.  In case studies (B to H) are increasing shear strength parameter of retained soil and restrained soil. All cases are considered with various distances from wall to surcharge. According to the soil conditions and distance from wall to surcharge, Wall depth, horizontal and vertical movement of ground and wall deflection are described. When retained and restrained soil reach stiff condition, then ground movement and wall deflection reach acceptable limit and wall depth become more safe and economical condition

Bifid Mandibular Canal: A Proportional Meta-Analysis of Computed Tomography Studies

Introduction. Growing body of evidences showed different grades in prevalence of bifid mandibular canals. Because the previous reviews focused solely on patient-level occurrence, hemi-mandible-level prevalence, bilateral symmetry, length, and diameter of bifid mandibular canals were required to be estimated collectively. The research question of this meta-analysis was “What is the prevalence of bifid mandibular canal among patients seeking computed tomography examinations”? Materials and Methods. In vivo, computed tomography, and cross-sectional studies were eligible. Studies, with less than 100 subjects or anatomic site restriction or controlled class of bifid mandibular canal, were excluded. Joanna Briggs Institute (JBI) critical appraisal tool for prevalence studies was used to assess methodological quality of all included studies. Random effect meta-analyses for proportion of bifid mandibular canal were done. Results. 40 studies met the inclusion criteria. All studies were selected for both systematic review and meta-analyses. Totally, 17714 patients and 31973 hemi-mandibles were included. All eligible studies showed moderate risk of bias on average. Resulting from the random effect model, more than 20% of patients seeking computed tomographic examinations had bifid mandibular canals (BMCs) which penetrated into slightly more than 14% of hemi-mandibles. Of the patients having bifid mandibular canals (BMCs), nearly 23% exhibited such anatomy on both sides of their mandibles. Estimated mean length and diameter of the accessory canals of bifid mandibular canals were 12.17 mm and 1.54 mm, respectively. Conclusion. The geographical locations, classifications, reliability test, and voxel size of computed tomography were all implicated in the prevalence of bifid mandibular canals along with gender and laterality, although considerable heterogeneity and bias were detected

Evidence of Second Canal between Permanent Mandibular Central and Lateral Incisors in China; a Systematic Review on CBCT Studies

Introduction. Evidence of second canal in permanent mandibular incisors is frequently questioned in dentistry. The difference in evidence between the two teeth is an interesting argument across different countries and ethnicities. So the aim of the systematic review was to investigate the evidence of second canal between permanent mandibular central and lateral incisors in China. Materials and Methods. The papers were selected from the electronic databases and hand searching according to inclusion and exclusion criteria. All qualified studies were judged by the reviewers. The selected studies were checked with Joanna Briggs Institute Critical Appraisal tool for prevalence studies. Finally, three studies were selected for the review and meta-analyses. The proportion of the second canal with its confidence interval and forest plot for the meta-analyses were calculated. Results. The evidences of second canal in permanent mandibular central and lateral incisors in China were 5.6% and 14.1%. Only one study reported bilateral symmetry of the second canal as 58.7% and 76.1% in the two types of teeth. Out of all canal anatomies, Vertucci’s type ΙΙΙ was dominant comprising 4.1% and 11.2% together with other second-canal types comprising 1.4% and 3% in permanent mandibular central and lateral incisors. When the proportions were meta-analyzed, mandibular central incisors had been less numerous OR = 0.35 [0.31, 0.40], 0.33[0.28, 0.39], and 0.42 [0.22, 0.79] in the evidence of second canal, of Type ΙΙΙ, and of other types except Type ΙΙΙ than mandibular lateral incisors in China. Out of all second-canal anatomies, Type ΙΙΙ presented 72.5% and 78.9% along with other second-canal types comprising 24.3% and 21.1% in the two teeth in China. Discussion. There was the evidence of second canal which deviated toward the permanent mandibular lateral incisor also in case of bilateral symmetry, the prevalence of Vertucci’s Type ΙΙΙ, and other second-canal types out of all canal anatomies