Chloride Profile Procedure
- Safety glasses are required at all times in the sample preparation lab
- Nitrile gloves are required when handling samples soaked with kerosene
The following steps begin with sample preparation and end with X-Ray Microscope (XGT) data collection.
- Core samples must be cut into slabs using the large auto-feed diamond saw in Benedict Lab.
- Billets must be cut from the slab(s) with the kerosene-cooled diamond saw (in hood) to represent cross-sections from the chloride-exposed surface.
- Billets must be dried in vented 50 degree C oven (to remove kerosene)and then fixed to glass slides with JB Kwik Weld.
- After JB Kwik Weld has set (a minimum of 20 minutes) a fresh flat surface must be ground into the billet using the mineral-oil cooled Ingram Thin Section Grinder.
- Immediately after grinding, samples must be cleaned of any debris by rinsing with kerosene (in hood).
- Dry billets in vented 50 degree C oven - the billets are now ready for analysis in the XGT.
The following describes calibration of the XGT. The XGT must be calibrated weekly to ensure quality measurements from the billet samples.
- Fix the aluminum, copper, and manganese standard on the removable XGT stage using double-sided tape. Put the stage in place, and gently tighten screws on either side insuring that the stage is held firmly in place.
- Raise the stage platform by rotating zoom knob until there is approximately 1mm of space between the top surface of the calibration standard and the mylar film.
- Turn on the video camera and open the video window on the computer screen. Use the lever on the XGT camera to zoom in to the maximum magnification (full left position). Check sample focus by raising or lowering the stage platform until a sharp focus is achieved.
- NOTE: The sample focus (i.e. the sample elevation) is correct when the area under the teardrop portion (picture needed) is clearly visible and in excellent focus.
- Zoom out the XGT camera (full right position) and navigate to the narrow seam between the copper and the aluminum on the calibration standard.
- Close all doors on XGT, double check to make sure steps 1-3 are completed. Vacuum can now be turned on.
- Open XGT_2700 Spectra Window.
- Select Measurements.
- Select Settings.
- Under settings, set preset to 100, select processing P1.
- Select Measurement again: Voltage current = 30kV; Current = 1.0mA; Trans. X-ray adjust = 8
- Select Options.
- Select Calibrate.
- Before clicking start, prepare the XGT-2700 video window to be moved back and forth according to LIVE TIME (prepare yourself as well). Calibration of the Machine will now begin.
- After calibration has begun, the camera will need to be moved back and forth from aluminum to copper at the following time intervals according to Table 1. These time intervals are Live time, so you must keep a close watch on this time and select Aluminum or Copper at precise times.
- NOTE: By simply clicking on the aluminum or copper on the video window on the computer screen, the stage will move back and forth between the elements.
- Move the camera back and forth according to the time intervals shown in Table 1.
- When the intervals have been completed, a data table will be presented with information containing Zero and Gain. Enter these Zero and Gain values in the XGT notebook.
- Navigate to a smooth portion of manganese on the calibration standard.
- NOTE: VAC can be left on until manganese sample has completed calibration
- Double-check that the manganese is in focus (same as step 3).
- Select Measurements.
- Select Settings.
- Change P1 to P2. P2 must be selected for this calibration.
- Select Measurement>>Clear
- Select Measurement>>Start
- Spectra will now be collected from the manganese sample. This will take 100 seconds as seen in Live Time on the XGT-2700 window.
- Turn VAC off
- After Spectra is collected, select File>>Save
- Save as c:/xgt/data/colo>>FWHM_Date.SPX
- Select Options>>FWHM>>Mn Calculate
- Write down value in logbook, then Save>>Close
The following steps describe how to collect the X-Ray Spectra from a concrete billet sample.
- Open the XGT sample chamber (white button on the from of XGT).
- Lower the stage to the lowest position by turning the coarse adjustment (Z-axis know) towards you until it stops.
- Use the XY joystick to bring the stage closest to you. If a sample is currently in the XGT sample holder, loosen the stage set screws in the front and right side and carefully lift out the sample holder.
- NOTE: If the concrete sample is large enough to make contact with the circular lead-glass window, BE SURE THE LEAD GLASS WINDOW IS CAREFULLY LIFTED TO ALLOW SAMPLE REMOVAL AND THEN RETURNED TO ITS ORIGINAL POSITION. If the circular glass is resting crooked in any way, there is the possibility of x-rays escaping from the machine.
- Place the concrete billet sample face-up in the middle of the sample holder using double-sided tape, and make sure the billet is parallel to the sides of the sample holder. The face of the concrete sample should be flat and level, not tipped or uneven in any way.
- Double-check that the billet is thoroughly held in place via tape on the sample holder, and then carefully place the sample holder on the sample stage. The circular glass may need to be lifted slightly at this point to allow the sample holder in. BE SURE THAT THE LEAD-GLASS WINDOW IS RETURNED PROPERLY TO ITS ORIGINAL POSITION. Once the sample holder is resting in the sample stage area, push the sample holder gently back and to the left and then gently tighten the set screws. The sample holder should be flat and level and thoroughly held in place.
The concrete sample must now be brought into the correct position to allow for X-Ray analysis.
- Keep the XGT sample chamber open
- Turn the MORITEX lamp on, and turn the brightness level all the way up.
- Use the XY joystick and move the sample directly beneath the lamp.
- Using the Coarse Z-axis knob, raise the sample platform to allow approximately 1 millimeter of space between the sample and the mylar film.
- Open the video camera (XGT-2700 VIDEO) window on the computer screen to view concrete sample. Click the viewing button on the camera window so the sample can be viewed live.
- When the sample is in view (approx. 1mm from camera/glass), slide the zoom lever from MIN to MAX. The zoom lever is hard to find, and is hidden up near the camera housing.
- As the zoom is in MAX, slowly move the Coarse Z-axis knob back and forth slowly so a very clear view of the sample comes into focus in the “Tear-drop” area on the XGT-2700 VIDEO window.
- After a very clear view is achieved, move the zoom lever back from MAX to MIN. After proper focus is achieved, the sample is then ready for analysis.
- On the XGT-2700 window, cross hairs will be shown on the sample portion. Select the correct spot on the sample (viewable from pink dot on scanned image) and proceed with starting the X-Ray of the sample.
X-Ray analysis of Sample will now begin with the following steps. Starting X-Ray Maps
- The sample position should be set and XGT sample chamber door closed. Ensure door is closed, the door has a safety switch, and if it is not closed, the x-ray source will not activate.
- Check XGT status, it should read: X-Ray: OFF, LN: OK (Green colored) and VAC: ON (Green colored).
- Select the XGT-2700 window on the computer monitor; select Measurements>>Settings select Processing time P1 and Preset time of 100 seconds.
- In the same window, select Measurement>>Voltage/Current and ensure X-Ray tube vol. = 30kV, Current = 1.0mA, and Trans. X-Ray adjust = 8.
- Select the XGT-2700 MAP window, select Measurement>>Scanning Preset and make sure Scanning Time = 1.
- In the same XGT 2700 MAP window, select Measurement>>Initial Mapping. MAKE SURE SETTINGS READ AS FOLLOWS: Live Time = 3150 sec/frame, Pixels = 256x256, Position = Current Position, and Elements = 17 Cl is selected.
- BEFORE CLICKING START, DOUBLE CHECK THAT VAC IS ON, THE POSITION OF THE SAMPLE IS CORRECT AND CHAMBER DOOR IS SHUT…NOW CLICK START. The map will be finished in precisely 53 minutes.
- NOTE: The red X-Ray indicator lamp (RED X-RAY ON LIGHT) will turn on after clicking start.
- When the map is finished, Scanning time will read 3148 on the XGT-2700 MAP window. While in the XGT-2700 MAP window, click the Modify Images Button (the button looks like a black X with a red dot in the middle). In the pull-down tab, select Cl Ka and select enhanced under the Conversion Table box. Then click OK.
- While still in the XGT-2700 MAP window, select Analyze>>RGB. The RGB window will now appear
- Assign the Ca Ka image to the red channel by clicking on the Ca Ka mini-image in the RGB window. Assign the Si Ka mini-image to the blue channel by clicking on the Si- Ka image in the RGB window. Assign the Cl Ka image to the green channel by clicking on the Cl Ka mini-image in the RGB window. When finished assigning each image to their respected color, select OK.
- In the XGT-2700 MAP window, select Display/Tile from the menu. A Tile window will appear, set the pull down menu to 512 dot and then click OK. This enlarges the 256x256 pixel maps to 512x512 pixels.
- The map is now ready to be saved.
The Concrete sample has now been mapped, and is ready for Spot Collection for Chloride Profiling. (Multi-point Analysis)
- When the Scanning Time = 3148 on the XGT-2700 MAP window, the sample has completed X-Ray analysis and the Chloride Profile can begin.
- XGT status should read: X-Ray: OFF, LN: OK (Green colored) and VAC: OFF (Red colored).
- In the XGT-2700 window, select Measurement>>Settings select Processing time P2 and Preset time of 100 seconds.
- In the XGT-2700 MAP window, use the cursor and scroll all the way down to the very bottom image that reads: R:Ca G:Cl B:Si
- Move now to the XGT-2700 window. select Analyze>>Multi-Point Analysis...
- Click the Select Image tab
- In the Select Display Image window, Click on: 20 Ca Ka, then click OK
- The Red image of the Map will now show up in the Multi-point Analysis window.
- Now Click Delete All in the same window. Click OK to Confirm.
- The correct number of points must now be selected within the paste areas of the billet section. This will take some practice to get used to.
- The following number of points must be completed in accordance with the corresponding sections of a billet:
Top Row Billet: Top = 24 pts; Middle = 18 pts; Bottom = 12 pts.
Preceding Row Billets: Top = 12 pts; Middle = 12 pts; Bottom = 12 pts.
- After selecting the correct number of points, Click Start. You will be prompted to save the file now. Save the file in the location that corresponds to the project being worked on.
- The Multi-point Analysis will now take 100 sec per point.
- After starting the Multi-point Analysis, Click copy to save a copy of the map in MS Paint.
- Open up MS Paint and copy the map and save it in the corresponding project folder.
- When the analysis is complete, click OK.
- In the XGT-2700 window select Measurement>>Settings and Select processing time back to P1 and click OK.
- The Multi-point analysis is now complete and a new X-Ray Spectra Map may be started.