土木工程外文翻译5Word文件下载.docx

1、of 50 g of cement and shake it in a closed glass bottle for two minutes and thenrevolve the sample gently using dry bar. Put the sample in a closed bottle and leaveit for two minutes. Put the sample in 170 sieve （90 microns） and move it, shakingthe sieve horizontally and rotationally, then confirm f

2、inishing the sieve test when therate of passing cement particles is not more than 0.5 g/min during the sieve process.Remove the fines carefully from the bottom of the sieve using a smooth brush. Then,collect and weigh the remaining particles on the sieve （W1）.Repeat the same test with another sample

3、. Then the residual weight for the secondtest is obtained （W2）. Calculate the values of the remaining samples throughR1 = （W1/50） 100R2 = （W2/50） The ratio （R） is calculated by taking the average of R1 and R2 to the nearest 0.1%and, in the case of deviating results of the two samples, more than 1%.

4、Do the test athird time and take the average of the three results.You can accept or refuse the cement based on the following condition:For Portland cement t he R must not exceed than 10%. For rapid hardening Portland cement the R must not exceed 5%.4.2.1.2 Initial and Final Setting Times of CementPa

5、ste Using Vicat ApparatusThe objective of this test is to define the time for initial and final setting of the pasteof water and cement with standard consistency by using a Vicat apparatus and determinewhether the cement is expired or can be used.The initial setting is the required time to set and a

6、fter that concrete cannot be pouredor formed; the final setting time is the time required for the concrete to be hardened.Vicat apparatus （Figure 4.2） consists of a carrier with needle acting under a prescribedweight. The parts move vertically without friction and are not subject to erosionor corros

7、ion. The paste mold is made from a metal or hard rubber or plastic likea cut cone with depth of 40 2 mm and the internal diameter of the upper face 70 5 mm and lower face 80 5 mm and provides a template of glass or similar materialsin the softer surface. Its dimensions are greater than the dimension

8、s of the mold.The needle is used to determine the initial setting time in a steel cylinder witheffective length 50 1 mm and diameter 1.13 0.5 mm. The needle measuring timeis in the form of a cylinder with length of 30 0.5 mm andheld by a 5 mm diameter ring at the free end to achieve distance between

9、 the end ofthe needle and the ring of 0.5 mm.The test starts by taking a sample weighing about 400 g and placing it on animpermeable surface and then adding 100 ml of water and recording zero measurementfrom the time of adding water to the cement and then mixing for 240 + 5 secondson the impermeable

10、 surface.To determine the initial setting time and calibrate the device until the needlereaches the base of the mold, then adjust the measuring device to zero and returnneedle to its original place.Fill the mold with cement paste with standard consistency and troll the surface,then put the mold for

11、a short time in a place that has the the temperature and humidityrequired for the test.Specific Surface （Wagner）-m2/kg365 days90 days28 days7 days20150 200 250 300304050Compressive Strength, MpaTransfer the mold to the apparatus under the needle, and then make the needleslowly approach the surface u

12、ntil it touches the pastes surface, stop it in place fora second or two seconds to avoid impact of primary speed, then allow the movingparts to implement the needle vertically in the paste.Grading depends on when the needle stops penetrating or after 30 seconds, whicheveris earlier, and indicates th

13、e distance between the mold base and the end of theneedle, as well as the time start from the zero level measurement.Repeat the process of immersing the needle in the same paste in different locationswith the distance between the immersing point and the edge of the mold orbetween two immersing point

14、s not less 10 mm after about 10 minutes, and clean theneedle immediately after each test.Record time is measured from zero up to 5 1 mm from the base of the mold asthe initial setting time to the nearest 5 minutes. Ensuring the accuracy of measurementof time between tests reduces embedment and the f

15、luctuation of successivetests. The needle is used to identify the final time of setting; follow the same stepsas in determining time of initial setting and increase the period between embedmenttests to 30 minutes.Record the time from zero measurement until embedment of the needle to a distanceof 0.5

16、 mm, which will be the final setting time. Control the impact of theneedle on the surface of the sample so the final setting time presents the effect ofthe needle. To enhance the tests accuracy reduce the time between embedment testsand examine the fluctuation of these successive tests. Record the f

17、inal setting timeto the nearest 5 mm.According to the Egyptian specifications the initial setting time must not be lessthan 45 minutes for all types of cement except the low heat cement, for which theinitial setting time must not be less 60 minutes. The final setting time must be shorterthan 10 hour

18、s for all types of cement.4.2.1.3 D ensity of CementThe purpose of this test is to determine the density of cement by identifying theweight and unit volume of the material by using the Le Chatelier density bottle. Thedetermination of the cement density is essential for concrete mix design and to con

19、trolits quality. This test follows specifications of the American Society for Testingand Materials, ASTM C188-84.The Le Chatelier device is a standard round bottle. Its shape and dimensions areshown in Figure 4.3. This bottle must have all the required dimensions, lengths, anduniform degradation and

20、 accuracy.The glass that is used in the Le Chatelier bottle must be of high quality and freefrom any defects. It should not interact with chemicals and have high resistance toheat and appropriate thickness to have a high resistance to crushing. Measurementsstart at the bottles neck and go from zero

21、to 1 mL and from 18 to 24 mL with accuracyto 0.1 mL. Each bottle must have a number to distinguish it from any other.Write on the bottle the standard temperature and the capacity in millimeters over thehighest point of grading.Processed sample cement weighing about 64 g to the nearest 0.05 g must be

22、tested.Fill the bottle with kerosene free from water and oil whose density is at least 62API. Up to point gradations between zero and 1 mL, dry the inner surface of thebottle at the highest level of kerosene if necessary, and use rubber on the surface ofthe table used for the test when filling the b

23、ottle.The bottle, which is filled with kerosene, is placed in a water bath and the firstreading to kerosene level is recorded. To record the first reading correctly install thebottle in the water bath vertically. Put a cement sample weighing 64 g with accuracyto 0.05 g inside the bottle with small b

24、atches at the same temperature of kerosene,taking into account when putting the cement inside the bottle to avoid cement droppingout or its adhesion on the internal surfaces of the bottle at the highest level. Thebottle can be placed on the vibrating machine when putting the cement inside thebottle

25、to expedite the process and prevent adhesion of granulated cement with theinternal surfaces of the bottle.After laying the cement inside the bottle, put a cap on the bottle mouth and thenspin diagonally on the surface so as to expel the air between the granules of cement,and continue moving the bott

26、le until the emergence of air bubbles stops from thekerosene surface inside the bottle.Put the bottle in the water bath and then take the final reading, and record thereading at the lower surface of kerosene so as to avoid the impact of surface tension.For the first and final readings, make sure tha

27、t the bottle is placed in a water bathwith constant temperature for a period not to exceed the difference in temperaturebetween the first and final readings of about 0.2C.The difference between the first and final reading is the volume of the movingliquid by the cement sample.The volume of the movin

28、g liquid = final reading first reading4.2.1.4 D efine Cement Fineness by Using Blaine ApparatusThis test is used to determine the surface area by comparing the test sample with thespecific reference. The greater surface area increases the speed of concrete hardeningand obtains early strength. This t

29、est determines the acceptance of the cement.There are many tests to define cement fineness and one is a Blaine apparatus asstated in many codes such as the Egyptian code.This test depends on calculating the surface area by comparing the sample test andthe reference sample using a Blaine apparatus to determine the time required to passa d