砂石级配的测定(英文版).doc

experiment report title Experiment curriculum : Material experiment and test technology Name of experiment : The grading test of sand Date of experiment : April 30, 2014 Site of experiment : On the fourth floor of the lab building Qingdao Technological University Professional class : Cass111 of Materials science and engineering Name of experimenter : Lixue Gan 201104002 Temperature : 20℃ Air humidity : 60% atmospheric?pressure : 100.92 KPa Introduction Aim of experiment ： Learn how to determine the distribution of sand ,and calculate the gradation and fineness modulus of sand . Experiment Principles : Sand，whose particle size is less than 5mm ，is fine aggregate in concrete. Sand can be divided into three types,named natural sand ,artificial sand and mixed sand.sand are required to have a good grading and certain fineness modulus in order to improve the workability of concrete. The grading of sand represents the distribution of sand’s grain size. An unreasonable sand grading result in the increase of cement dosage in unit volume concrete and the decrease of concrete workability. The degree of fineness modulus represents the degree of sand thickness.Sand whose fineness modulus is greater than 3.7 or less than 0.7 is not used for concrete. The smaller the fineness modulus of sand is ,the more cement will be used when the concert are mixed up. Sieving method are usually used to test the grading of sand. A series of sieves whose mesh size are different are used when testing sand gradation by the method of sieving.the mesh size of the sieves include 4.75mm , 2.36mm , 1.18mm , 0.60mm , 0.30mm , 0.15mm , 0.075mm. The s and sample go through the sieves in order.We have to weigh the sand remained in every sieves.Than calculate the percentage of single screened residue (a1.a2.a3.a4.a5.a6.a7) and percentage of cumulative screened residue