砂石级配的测定英文版Word文件下载.docx

1、 20Air humidity : 60%atmosphericpressure : 100.92 KPa IntroductionAim 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 b

2、e 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 sands grain size. An unreasonable sand grading resul

3、t 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 s

4、and 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

5、 , 0.60mm , 0.30mm , 0.15mm , 0.075mm. The sand 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 （A1 .A2 .A3 .A4 .A5 .A6 .A7 ） . Than

6、we can get the gradation and fineness modulus of sand .The following are formulas for the gradation and fineness modulus of sand.The gradation of sand : a=m/M4.75mmm1a1A1= a12.36mmm2a2A2=a1+a21.18mmm3a3A3= a1+ a2+ a30.60mmm4a4A4= a1+ a2+ a3+a40.30mmm5a5A5= a1+ a2+ a3+a4+a50.15mmm6a6A6= a1+ a2+ a3+a4

7、+a5+ a60.075mmM7a7A7= a1+ a2+ a3+a4+a5+ a6+ a7Fineness modulus of sand:U=（A2+A3+A4+A5+A6）-5A1（100-A1）MeasurementProcedures1. Take 1100 grams of sand ,and put them into the oven to dry them up at 105 degrees Celsius.It takes about 15-20 minutes.Then screen the dry sand in sieve whose mesh is 9.50mm.

8、Divide the rest sand into two parts that will be used later.2. take 500 grams of sand that have been dried up,accurate to within 1gram.Then put the sample on the sieves sorted by mesh size from largest to smallest and sieve them out.3. Put the sieves with sand in the sieve shaker .Than open the siev

9、e shaker .Shut down the sieve shaker 10 minutes later and than take the sieves with sand down.After this progress ,the sieves should be screened by hand from the largest one to the smallest one.4. Weigh the remained sand in every sieve and record themin the table. If the sieve residue is more than 2

10、00 grams,the sample should be divided into two parts to be screened one more time.5. .Than calculate the percentage of single screened residue , percentage of cumulative screened residue and fineness modulus of sand.6. Two experiments should be done to take the average,If the sum of remained sand is

11、 less than 495 grams,Another experiment should be done.EquipmentandExperimentalSetup1. Blast oven2. Balance（ accurate to 0.001 grams ） 3. enamel disc and brush4. sieve shaker5. sieves （ mesh size: 4.75mm. 2.36mm. 1.18mm. 0.60mm. 0.30mm. 0.15mm. 0.075mm ）Data records and Data processingThe table of e

12、xperimental data records9.50mm sieve allowance 10gScreen residue percentageThe size of sieves hole4.752.361.180.600.300.150.075Group1M41191361058891910percentage of single screened residue8.2%3.8%27.2%21.0%17.618.21.820percentage of cumulative screened residue12.0%39.2%60.2%77.89697.8%99.8%fineness

13、modulus2.66Group2Sieve allowance1351068927.0%21.2%17.8%18.2%2.012.0%39.0%78.0%96.2%98.0%100a1=41500=8.2%a2=19500=3.8%a3=136500=27.2%a4=105500=21.0%a5=88500=17.6%a6=91500=18.2%a7=9500=1.80%A1= a1=8.2%A2= a1+a2=8.2%+3.8%=12.0%A3= a1+a2+a3=8.2%+3.8%+27.2%=39.2%A4= a1+a2+a3+a4=8.2%+3.8%+27.2%+21.0%=60.2%A5= a1+a2+a3+a4+a5=8.2%+3.8%+27.2%+21.0%+17.6%=77.8%A6=a1+a2+a3+a4+a5+a6=8.2%+3.8%+27.2%+21.0%+17.6%+18.2%=96.0%u1=