The authors appreciate the financial support from the National Basic Research Program of China (973 Program) under the contract No. 2015CB655105, the Natural Science Foundation the contract No. 51308262, and the Natural Science Foundation of Jiangsu Province under the contract No. BK20131012.

Caution: Several of the chemicals, such as silver nitrate, potassium chromate, and concentrated sulfuric acid, used in the testing process are acutely toxic and corrosive. Please adopt appropriate safety measures while using them, including the wear of safety glasses, gloves, lab coat, etc.
1. Preparation of Paste Specimens
<ol>
	<li>Preparation of the mold
	<ol>
		<li>Use a brush to clean up a mold of size 70 mm &#215; 70 mm &#215; 70 mm, making sure that the inner surfaces of the mold are impurity-free.</li>
		<li>Brush mold-release diesel oil evenly on the inner surfaces of the mold using another brush.</li>
	</ol>
	</li>
	<li>Molding Paste Specimen
	<ol>
		<li>Use an electronic balance to weigh 1,000 g of water into a 1,500 mL plastic cup and 2,000 g of cement into a 3,000 mL plastic basin.</li>
		<li>Add 1,000 g water and 2,000 g of cement into a 5 L mixing pot sequentially. The water to cement ratio is 0.5.</li>
		<li>Put the mixing pot on the base of a cement paste mixer and fasten it after raising it to the stirring position.</li>
		<li>Mix at 65 rpm for 90 s.</li>
		<li>Let the mixture sit for 30 s. During this period, scrape off the paste on the inner wall of pot using a scraper knife and mix it into the rest of the pot. Mix at 130 rpm for 60 s.</li>
		<li>Remove the mixing pot from the mixer. Pour the well-mixed cement paste into the mold. Shovel the cement paste with a scraper knife and vibrate the mold for several seconds to compact the paste on a vibrating table.</li>
		<li>After filling up the mold, seal the mold surface with cling film to prevent moisture evaporation. Let sit for 24 h in the molding at 23 &#177; 2 &#176;C.</li>
	</ol>
	</li>
	<li>Curing
	<ol>
		<li>Remove the hardened paste specimens from the mold.</li>
		<li>Place hardened paste specimens in a curing room at 23 &#177; 2 &#176;C and 95% relative humidity for 60 d.</li>
	</ol>
	</li>
	<li>Cutting
	<ol>
		<li>Take specimens out of the curing room after 60 d.</li>
		<li>Fix the specimen on a high precision cutting machine and cut off 20 mm from the mold-free surface. The processed specimens of size 70 mm &#215; 70 mm &#215; 50 mm will be subjected to chloride ingression exposure afterwards.</li>
	</ol>
	</li>
	<li>Sealing with epoxy resin
	<ol>
		<li>Taking the cut-surface as the exposure surface, seal the other five surfaces of the specimen (70 mm &#215; 70 mm &#215; 50 mm) with epoxy resin using a brush. The volume of epoxy resin used for each specimen is about 30 mL. Harden the epoxy resin through air exposure for 24 h. 
		NOTE: Prepare specimens for chloride ingression exposure after the epoxy resin has hardened.</li>
	</ol>
	</li>
</ol>
2. Cyclic Wetting and Drying
<ol>
	<li>Add 0.35 kg of NaCI and 9.65 kg of deionized water into a 15 L plastic bucket for a NaCI solution with a mass ratio of 3.5%.</li>
	<li>With the exposure surface facing down, place specimens in a plastic box (50 cm &#215; 30 cm &#215; 20 cm) with two braces laid on the bottom. The brace can be stainless steel bars or plastic grid plates. The presence of the brace allows the exposure surface to take about 1.0 cm of space to the bottom of the box.</li>
	<li>Pour the 3.5% NaCI solution slowly into the plastic box and stop when the liquid level is about 1.0 cm above the exposure surface. Seal the box with a plastic film (about 0.25 mm thickness) to prevent concentration changes caused by evaporation. Then, put the plastic box in a room with constant temperature of 23 &#177; 2 &#176;C and humidity of 65 &#177; 2%.</li>
	<li>Starting from the time of pouring the NaCl solution, soak specimens for 24 h for the wetting process.</li>
	<li>Take specimens out of solution after wetting for 24 h, wipe off the residual solution with a towel gently, and put them in the same constant temperature and humidity room for 6 d, which is the drying process.</li>
	<li>After drying for 6 d, put specimens back into the NaCI solution again.</li>
	<li>Repeat steps 2.5 and 2.6 (7 d for one wetting-drying cycle) for a total of 12 cycles.</li>
</ol>
3. Grinding Powder Samples
<ol>
	<li>After 12 wet-dry cycles, fix the specimen on the base of high precision computer numerical controlled (CNC) grinding machine, which was converted from a milling machine by replacing the original cutter with a titanium alloy cutter.</li>
	<li>Place powder-collecting paper around the specimen on the base of a grinding machine before starting to grind.</li>
	<li>Start the high precision CNC grinding machine and wait until the system is loaded.</li>
	<li>Press the &#34;ZERO&#34; button and the subsequent &#34;X&#8594;0&#34;, &#34;Y&#8594;0&#34;, &#34;Z&#8594;0&#34; buttons to make the operation desk and milling cutter return to the coordinate origin automatically.</li>
	<li>Press &#34;Manual Data Input (MDI)&#34;, double click &#34;PROGRAM&#34;, input &#34;N3S1000&#34; and click &#34;INPUT&#34;, then press &#34;CYCLE START&#34; to start the main shaft. Note that &#34;N3S1000&#34; means the revolving speed of the shaft is being set at 1000 rpm.</li>
	<li>Load the main grinding program: Press &#34;MDI&#34;, click &#34;PROGRAM&#34; repeatedly to find &#34;PROGRAM (CATALOG)&#34; page, and select the appropriate program. Next, click &#34;EDIT&#34;, and press &#34;INPUT&#34; to load the main program. 
	NOTE: The main program can be personalized according to a specific grinding requirement, including settings of the total grinding depth, number of layers, thickness of each layer, and time interval between grinding two layers. For this protocol, the total grinding depth is 10 mm, and the number of layers is 20; the grinding thickness of each layer is 0.5 mm; and the time interval between grinding layers is 60 s. See the disclosure for details of program.</li>
	<li>Set the milling cutter position: First, click &#34;MANUAL OPERATION&#34; and then &#34;MAINSHAFT FORWARD&#34; to rotate the main shaft. Next, click &#34;HAND WHEEL&#34; and manually adjust the cutter to the ready-to-grind position (usually on the one third of the front-left surface of specimen). Finally, click &#34;SET&#34; and &#34;X&#34;, &#34;INPUT&#34;, &#34;Y&#34;, &#34;INPUT&#34;, &#34;Z&#34;, and &#34;INPUT&#34; buttons subsequently. Record the relative coordinates as the original space coordinates to finish cutter setting.</li>
	<li>Launch the main grinding program: Press &#34;START&#34;, then click &#34;AUTO&#34; and &#34;CYCLE START&#34; buttons subsequently. The machine starts grinding automatically as pre-programmed. 
	NOTE: During the grinding process, powder will be accumulated on the collecting paper which is pre-spread on the base of machine. After grinding each layer, the milling cutter will rise away from the specimen and remain stationary in the X, Y, Z directions for 60 s as programmed. Collect a powder sample during the 60 s break and re-spread the collecting paper. 
	CAUTION: Though the milling cutter stops moving in the X, Y, Z directions, it is still rotating. Attention should be paid to avoid touching the milling cutter with any body parts to avoid injury. Besides, it is necessary to use a mask and gloves due to the dust generated during grinding process.</li>
	<li>Shut down the machine after finishing grinding.</li>
</ol>
4. Detecting Chloride Content7
<ol>
	<li>Preparation of solution
	<ol>
		<li>Potassium chromate solution
		<ol>
			<li>Dissolve 5 g of potassium chromate in 20 mL of deionized water. Add 10 mg of silver nitrate. Shake well and let sit for 24 h. 
			CAUTION: Potassium chromate and silver nitrate are toxic. It is necessary to wear rubber gloves and a mask while using them.</li>
			<li>Filter the solution into a conical flask with a funnel and filter paper and move it into a 100 mL volumetric flask. Add deionized water until reaching the 100 mL calibration mark. The potassium chromate indicator of 5% concentration is obtained.</li>
		</ol>
		</li>
		<li>Prepare 0.5% phenolphthalein solution: Dissolve 0.5 g of phenolphthalein in 75 mL of ethyl alcohol. Add 25 mL of deionized water and shake well.</li>
		<li>Prepare dilute sulfuric acid: Dissolve 5 mL of concentrated sulfuric acid (98.3%) in 100 mL of deionized water. 
		CAUTION: Concentrated sulfuric acid is very corrosive. It is necessary to wear rubber gloves, a mask, and goggles while using it.</li>
		<li>NaCI standard solution
		<ol>
			<li>Heat about 2 g of pure sodium chloride under 200 - 300 &#176;C in a crucible with an electric furnace, and stir with a glass rod during the process until there are no sounds of salt cracking (devoid of water).</li>
			<li>After cooling in a desiccator, take 1.169 g of NaCI crystals, dissolve in a 1,000 mL volumetric flask with 100 mL deionized water. Add deionized water until reaching the 1,000 mL calibration mark. An NaCl standard solution of 0.02 M is obtained. Calculate the concentration of the NaCl standard solution with the equation below: 
			<img alt="Equation 1" src="/files/ftp_upload/56268/56268eq1.jpg" /> 
			where, CNaCl is the standard concentration of NaCl solution, mol/L; V is the volume of solution, L; M is the molar mass of NaCl, 58.45 g/mol; m is the mass of NaCl, g.</li>
		</ol>
		</li>
		<li>Silver nitrate solution
		<ol>
			<li>Dissolve 1.7 g of silver nitrate in 100 mL of deionized water with a 200 mL breaker. Move it into a 1,000 mL brown volumetric flask and add deionized water up to the 1,000 mL calibration mark.</li>
			<li>Pipette three 10 mL (V1) units of 0.02 M standard NaCI solution into three conical flasks. Add 10 drops of potassium chromate indicator in each with a dropper.</li>
			<li>Titrate the solution from step 4.1.5.2 with the prepared silver nitration from step 4.1.5.1. Stop when the solution becomes reddish and the red color does not fade away. Record the volume of consumed silver nitration solution (V2). Calculate the standard concentration of silver nitration solution with the equation below, and take the mean value of three testing results. 
			<img alt="Equation 2" src="/files/ftp_upload/56268/56268eq2.jpg" /> 
			Where, CAgNO3 is the concentration of silver nitrate solution, mol/L; V1 is the volume of NaCl solution, 10 mL; V2 is the volume of silver nitrate solution consumed, mL.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Water-soluble chloride content
	<ol>
		<li>Grind every sample obtained in section 3 in a mortar until it can be sifted through an 80 &#181;m sieve. Heat and dry the sifted samples at 105 &#176;C for 2 h in an oven.</li>
		<li>Take 2 g of each dried sample, put them in 100 mL plastic bottles, add 50 mL (V3) of deionized water with a 50 mL measuring pipette, and seal the bottles with caps. Shake the bottles violently to guarantee that the sample and deionized water are well-mixed.</li>
		<li>Fasten plastic bottles on an automatic vibrator and vibrate for 24 h to dissolve the water-soluble chloride from samples.</li>
		<li>Filter the solution in bottles after vibrating for 24 h with funnels and filter paper. Pipette two 10 mL (V4) units of filtrated solution from every bottle into two conical flasks.</li>
		<li>Add two drops of phenolphthalein solution to each conical flask to make the solution present purplish red. Neutralize the solution to colorless with dilute sulfuric acid.</li>
		<li>Add 10 drops of potassium chromate indicator into the colorless solution and titrate immediately with silver nitrate solution. Shake the conical flask manually during titrating to make sure that the chloride ions react with silver nitrate quickly and completely. Stop titrating when the solution becomes reddish and the red color does not fade away. Record the volume of consumed silver nitrate solution (V5).</li>
		<li>Calculate the content of water-soluble chloride with the equation below and take the mean value of the two testing results. 
		<img alt="Equation 3" src="/files/ftp_upload/56268/56268eq3.jpg" /> 
		where, Cw is the water-soluble chloride content in the paste sample, % cement; ms is the mass of powder sample, 2 g; V3 is the volume of deionized water used to dissolve sample, 50 mL; V4 is the volume of filtrated solution extracted at each nitration, 10 mL; V5 is the volume of silver nitrate solution consumed at each nitration, mL; Mcl is the molar mass of Cl, 35.5 g/mol.</li>
		<li>Plot water-soluble chloride profiles after getting the chloride content at different depths of paste specimens.</li>
	</ol>
	</li>
</ol>
5. Accuracy Test of Grinding Thickness
<ol>
	<li>Set five grinding thicknesses: 1.0 mm, 0.5 mm, 0.2 mm, 0.1 mm, and 0.05 mm in the main grinding program. Grind with each thickness five times.</li>
	<li>Measure the thickness of specimen before grinding (H1) and after grinding (H2) with a vernier caliper, and calculate the practical grinding thickness with the equation below. Do not take the specimen down from the machine during measuring to guarantee the reliability of measurement. 
	<img alt="Equation 4" src="/files/ftp_upload/56268/56268eq4.jpg" /> 
	Where, P is the practical grinding thickness, mm; H1 is the thickness of specimen before grinding, mm; H2 is the thickness of specimen after grinding, mm.</li>
</ol>

<ol>
	<li>Byang, H. O., Jang, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+material+and+environmental+parameters+on+chloride+penetration+profiles+in+concrete+structures.">Effects of material and environmental parameters on chloride penetration profiles in concrete structures.</a> Cem. Concr. Res. 37 (1), 47-53 (2007).</li><li>Mehta, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Concrete: structure, properties and materials. , 105-169 (1986).</li><li>Khelidj, A., Loukili, A., Bastian, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+study+of+the+hydro-chemical+coupling+inside+maturing+concretes:+effect+on+various+types+of+shrinkage.">Experimental study of the hydro-chemical coupling inside maturing concretes: effect on various types of shrinkage.</a> Mater. Struct. 31 (9), 588-594 (1998).</li><li>Nielsen, E. P., Geiker, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chloride+diffusion+in+partially+saturated+cementitious+material.">Chloride diffusion in partially saturated cementitious material.</a> Cem. Concr. Res. 33 (1), 133-138 (2003).</li><li>He, F., Shi, C., Yuan, Q., Chen, C., Zheng, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AgNO3-based+colorimetric+methods+for+measurement+of+chloride+penetration+in+concrete.">AgNO3-based colorimetric methods for measurement of chloride penetration in concrete.</a> Constr. Build. Mater. 26 (1), 1-8 (2012).</li><li>Collepardi, M., Turriziani, R., Marcialis, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Penetration+of+chloride+ions+into+cement+pastes+and+in+concretes.">Penetration of chloride ions into cement pastes and in concretes.</a> J. Am. Ceram. Soc. 55 (10), 534-535 (1972).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> JTJ 270-98. Testing Code of Concrete for Port and Waterwog Engineering. , 202-207 (1998).</li><li>Chang, H., Mu, S., Xie, D., Wang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+pore+structure+and+moisture+distribution+on+chloride+"maximum+phenomenon"+in+surface+layer+of+specimens+exposed+to+cyclic+drying-wetting+condition.">Influence of pore structure and moisture distribution on chloride "maximum phenomenon" in surface layer of specimens exposed to cyclic drying-wetting condition.</a> Constr. Build. Mater. 131 (1), 16-30 (2017).</li><li>Lu, C., Gao, Y., Cui, Z., Liu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Analysis+of+Chloride+Penetration+into+Concrete+Subjected+to+Drying-Wetting+Cycles.">Experimental Analysis of Chloride Penetration into Concrete Subjected to Drying-Wetting Cycles.</a> J. Mater. Civil. Eng. 27 (12), 1-10 (2015).</li><li>Xu, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Properties of Chloride Ions Transportation in Concrete under Different Drying-wetting Cycles. , (2012).</li><li>Zhao, T., Fan, H., Cao, W., Wang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concrete+powder+grinding+machine.">Concrete powder grinding machine.</a> China patent. , (2012).</li></ol>

The authors have nothing to disclose.

The grinding error of the high precision CNC milling machine is controlled within 0.04 mm and the standard deviation is less than 0.03 mm (Table 1)8. It proves that this milling method has a high degree of accuracy and stability in the measurements of chloride contents as a function of depth, contributing to a better illustration of real chloride distribution in the specimens.
When the testing interval is 0.5 mm, with the depth from exposure surface inc...

The chloride induced corrosion of reinforcing steel is one of the major causes jeopardizing the service life of reinforced concrete structures exposed to an aggressive environment (e.g., marine environment or deicing salts environment). The chloride distribution can be used for investigations of the chloride penetration rate, the amount of steel corrosion, and predictions of the service life. Therefore, a precise chloride distribution is of great significance for the durability research of concrete structures.
Mechanisms or combined actions of multi-mechanisms are responsible for chloride transport in concrete under specific environments1. In submerged parts of marine structures, pure diffusion is the only mechanism driving chloride ingress2, which causes the chloride content to decrease with increasing depth. Concrete is in a non-saturated state3 when subjected to a wetting-drying environment such as a marine tidal zone or a deicing salt environment. In such conditions, the process of chloride ingress becomes very complicated and both diffusion and capillary suction operate in chloride transport4. Thus, the chloride distribution under wetting-drying conditions is probably more complicated than in a submerged condition. Therefore, the chloride distribution under cyclic wetting-drying conditions needs to be studied more precisely.
The chloride distribution in cement-based materials is usually represented by a chloride profile. The accuracy of a chloride profile mainly depends on two aspects: the accuracy of chloride content and the accuracy of chloride distribution along the depth. Regarding the chloride content test, the basic principle is based on the chemical reaction between (Cl-) and (Ag+)5,6, though different standards require different specific operations. The exact chloride content can be acquired as long as specific operations are followed. However, the accuracy of the chloride distribution along the depth relies mainly on the accuracy of the sampling position. The methods already known for obtaining power samples at different depths of specimen are an electric drill, a normal grinding machine, and a profile grinder. Unfortunately, they all share a disadvantage as the accuracy is low when the grinding thickness or sampling interval is small. Thus, the requirement of investigating chloride distribution in the surface layer of specimens under cyclic wetting-drying condition is not met. Therefore, a new method that can allow a smaller sampling interval (e.g., less than 0.5 mm) and reduce error to the minimum (e.g., less than 0.05 mm) is needed.
The detailed protocol here offers a more accurate way to get a chloride profile by improving the precision of chloride distribution along the depth.

<table>
	<tbody>
		<tr>
			<td>Cement</td>
			<td>Jiangnan Xiaoyetian</td>
			<td>P.II. 52.5</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chromate, 99.7%</td>
			<td>Tianjin Kemiou</td>
			<td>HG391887</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Ethyl alcohol</td>
			<td>Sinopharm</td>
			<td>XK10009257</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver nitrate, 99.8%</td>
			<td>Sinopharm</td>
			<td>7761888</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Phenolphthalein, 99.5%</td>
			<td>Tianjin Fuchen</td>
			<td>XK1301100017</td>
			<td></td>
		</tr>
		<tr>
			<td>Concentrated sulfuric acid, 98.3%</td>
			<td>Shanghai Lingfeng</td>
			<td>XK1301100085008</td>
			<td>Highly corrosive</td>
		</tr>
		<tr>
			<td>Sodium chloride, 99.7%</td>
			<td>Xilong Scientific</td>
			<td>XK1320100153</td>
			<td></td>
		</tr>
		<tr>
			<td>Diesel oil</td>
			<td>China Petroleum</td>
			<td>0#</td>
			<td></td>
		</tr>
		<tr>
			<td>Epoxy resin</td>
			<td>Yifeng Chemical</td>
			<td>E44-6101</td>
			<td></td>
		</tr>
		<tr>
			<td>Deionized water</td>
			<td>Beijing Liyuan</td>
			<td>PUW-10N</td>
			<td></td>
		</tr>
		<tr>
			<td>CNC Milling meachine</td>
			<td>Foshan Xiandao Digital Technology</td>
			<td>C31E</td>
			<td></td>
		</tr>
		<tr>
			<td>Cement paste mixer</td>
			<td>Wuxi Construction and Engineering</td>
			<td>NJ160</td>
			<td></td>
		</tr>
		<tr>
			<td>High precision cutting machine</td>
			<td>Buehler</td>
			<td>2215</td>
			<td></td>
		</tr>
		<tr>
			<td>Mixing spot</td>
			<td>Wuxi Construction and Engineering</td>
			<td>JJ-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Scraper knife</td>
			<td>Jinzheng Building Materials</td>
			<td>CD-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Cling film</td>
			<td>Miao Jie</td>
			<td>65300</td>
			<td></td>
		</tr>
		<tr>
			<td>Mold (70mm&#215;70mm&#215;70mm)</td>
			<td>Jingluda</td>
			<td>ABS707</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic box</td>
			<td>Fangao Household</td>
			<td>32797</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel brace</td>
			<td>An Feng</td>
			<td>316L</td>
			<td></td>
		</tr>
		<tr>
			<td>Paper</td>
			<td>Deli</td>
			<td>A4</td>
			<td></td>
		</tr>
		<tr>
			<td>Oven</td>
			<td>Shanghai Huatai</td>
			<td>DHG-9070A</td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic vibrator</td>
			<td>Lichen</td>
			<td>HY-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibrating table</td>
			<td>Jianyi</td>
			<td>GZ-75</td>
			<td></td>
		</tr>
		<tr>
			<td>plastic film</td>
			<td>Miao Jie</td>
			<td>65303</td>
			<td></td>
		</tr>
		<tr>
			<td>Vernier caliper</td>
			<td>Links</td>
			<td>601-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Electronic balance</td>
			<td>Setra</td>
			<td>BL-4100F</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic bottle</td>
			<td>Lining Plastic</td>
			<td>454</td>
			<td></td>
		</tr>
		<tr>
			<td>Brush</td>
			<td>Huoniu</td>
			<td>3#</td>
			<td></td>
		</tr>
		<tr>
			<td>Mask</td>
			<td>UVEX</td>
			<td>3220</td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>Ammex</td>
			<td>TLFGWC</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic cup</td>
			<td>Maineng</td>
			<td>MN4613</td>
			<td></td>
		</tr>
		<tr>
			<td>Desiccator</td>
			<td>Shenfei</td>
			<td>GZ300</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Hangzhou Wohua</td>
			<td>9614051</td>
			<td></td>
		</tr>
		<tr>
			<td>Dropper</td>
			<td>Huaou</td>
			<td>1630</td>
			<td></td>
		</tr>
		<tr>
			<td>Breaker</td>
			<td>Huaou</td>
			<td>1101</td>
			<td></td>
		</tr>
		<tr>
			<td>Funnel</td>
			<td>Huaou</td>
			<td>1504</td>
			<td></td>
		</tr>
		<tr>
			<td>Measuring cylinder</td>
			<td>Huaou</td>
			<td>1601</td>
			<td></td>
		</tr>
		<tr>
			<td>volumetric flash</td>
			<td>Huaou</td>
			<td>1621</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical flash</td>
			<td>Huaou</td>
			<td>1121</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Huaou</td>
			<td>1633</td>
			<td></td>
		</tr>
		<tr>
			<td>Burette</td>
			<td>Huaou</td>
			<td>1462</td>
			<td></td>
		</tr>
		<tr>
			<td>Mortar</td>
			<td>Huaou</td>
			<td>YBMM254</td>
			<td></td>
		</tr>
		<tr>
			<td>80&#181;m sieve</td>
			<td>Shanghai Dongxing</td>
			<td>KJ-80</td>
			<td></td>
		</tr>
		<tr>
			<td>Crucible</td>
			<td>Oamay</td>
			<td>GYGG</td>
			<td></td>
		</tr>
		<tr>
			<td>Electric furnace</td>
			<td>Tyler</td>
			<td>SX-B06</td>
			<td></td>
		</tr>
	</tbody>
</table>

detecting the water-soluble chloride distribution of cement paste in a high-precision way

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a high-precision chloride profile. Firstly, paste specimens are molded, cured, and exposed to cyclic wet-dry conditions. Then, powder samples at different specimen depths are grinded when the exposure age is reached. Finally, the water-soluble chloride content is detected using a silver nitrate titration method, and chloride profiles are plotted. The key to improving the accuracy of the chloride distribution along the depth is to exclude the error in the powderization, which is the most critical step for testing the distribution of chloride. Based on the above concept, the grinding method in this protocol can be used to grind powder samples automatically layer by layer from the surface inward, and it should be noted that a very thin grinding thickness (less than 0.5 mm) with a minimum error less than 0.04 mm can be obtained. The chloride profile obtained by this method better reflects the chloride distribution in specimens, which helps researchers to capture the distribution features that are often overlooked. Furthermore, this method can be applied to studies in the field of cement-based materials, which require high chloride distribution accuracy.

The original data and statistical results about the accuracy of grinding thickness are collected (Table 1)8. Mean and error are used to reflect the accuracy and standard deviation&#160;(SD) is used to reflect the consistency of this method.
The water-soluble chloride content of testing interval 0.5 mm (Figure 1) and 2.0 mm (Figur...

Watch this Scientific Journal Video about Detecting the Water-soluble Chloride Distribution of Cement Paste in a High-precision Way at JoVE.com

Detecting the Water-soluble Chloride Distribution of Cement Paste in a High-precision Way

A protocol for obtaining a water-soluble chloride profile by using a high precision milling method is presented.

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a ...

detecting-water-soluble-chloride-distribution-cement-paste-high

Research

Education

JoVE Core

JoVE Journal

Civil Engineering

Engineering

Unit 1

Introduction to Concrete

SCIENTISTS IN ACTION

9.5K Views.  Southeast University. Протокол для получения водорастворимых хлорид профиль с помощью высокой точности, фрезерные метод представлен.

Video: Detecting the Water-soluble Chloride Distribution of Cement Paste in a High-precision Way

The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the standard quantum limit or to cool mechanical systems to their quantum ground state. This is for example the case of future gravitational wave observatories, whose sensitivity to gravitational wave signals is expected to be limited in the most sensitive frequency band, by atomic vibration of their mirror masses. One promising approach being pursued to overcome this limitation is to employ higher-order Laguerre-Gauss (LG) optical beams in place of the conventionally used fundamental mode. Owing to their more homogeneous light intensity distribution these beams average more effectively over the thermally driven fluctuations of the mirror surface, which in turn reduces the uncertainty in the mirror position sensed by the laser light.
We demonstrate a promising method to generate higher-order LG beams by shaping a fundamental Gaussian beam with the help of diffractive optical elements. We show that with conventional sensing and control techniques that are known for stabilizing fundamental laser beams, higher-order LG modes can be purified and stabilized just as well at a comparably high level. A set of diagnostic tools allows us to control and tailor the properties of generated LG beams. This enabled us to produce an LG beam with the highest purity reported to date. The demonstrated compatibility of higher-order LG modes with standard interferometry techniques and with the use of standard spherical optics makes them an ideal candidate for application in a future generation of high-precision interferometry.

Large laser-interferometers are being constructed to create a new type of astronomy based on gravitational waves. Their sensitivities, as for many other high-precision experiments, are approaching fundamental noise limits such as the atomic vibration of their components. We are pioneering technologies to overcome these limits using novel laser beam shapes.

Thermal noise in high-reflectivity mirrors is a major impediment for several  types of high-precision interferometric experiments that aim to reach the  ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects

A procedure to measure the bulk lifetime (&#62;100 &#181;sec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min&#160;using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (&#60;1012 cm-3).

A RT liquid surface passivation technique to investigate the recombination activity of bulk silicon defects is described. For the technique to be successful, three critical steps are required: (i) chemical cleaning and etching of silicon, (ii) immersion of silicon in 15% hydrofluoric acid and (iii) illumination for 1 min.

A procedure to measure the bulk lifetime (&#62;100 &#181;sec) of silicon wafers by temporarily attaining a very high level of surface passivation when ...

In Vitro Culture of Epicardial Cells From Mouse Embryonic Heart

During embryogenesis, the epicardial contribution to coronary vasculature development has been very well established. Cells derived from the epicardium differentiate into smooth muscle cells, fibroblasts and endothelial cells that contribute to the formation of coronary vessels. Here we have established an in vitro culture method for embryonic epicardial cells. Using genetic labelling, we have demonstrated that the majority of the migrating cells in our explant culture are of epicardial origin. Epicardial explant cells also retain the expression of epicardial markers (Wt1 and Tbx18). Furthermore, we provide evidence that epicardial explant cells undergo epithelial to mesenchymal transition (EMT), migrate and differentiate into smooth muscle cells after Transforming growth factor beta 1 (TGF-&#946;1) treatment in a manner indistinguishable from that of epicardial cells in vivo. In conclusion, we provide a novel method for the culture of embryonic epicardial cells, which will help to explore the role of specific genes in epicardial cell biology.

In Vitro Culture of Epicardial Cells From Mouse Embryonic Heart

The epicardium is an essential source of multipotent cardiovascular progenitor cells and paracrine factors that are required for cardiovascular development and regeneration. We describe here a method to culture mouse embryonic epicardial cells.

During embryogenesis, the epicardial contribution to coronary vasculature development has been very well established. Cells derived from the epicardium ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (&lt;2 wt% non-calcium impurities, according to ICP-MS analysis). Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6&#8729;H2O). Based on its ability to adsorb Ni2+, as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.

A protocol for the parallel production of precipitated calcium carbonate and zeolitic material from blast furnace slag via mineral carbonation and alkaline hydrothermal conversion, respectively, is presented. The performance of the zeolitic material towards nickel adsorption is tested.

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with ...

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&#233; Fringes

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moir&#233; method or the spatial phase-shifting sampling moir&#233; method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moir&#233; fringes are generated to reconstruct a multiplication moir&#233; pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moir&#233; method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moir&#233; fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moir&#233; techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&amp;#233; Fringes

A sampling moir&#233; technique featuring 2-pixel and multi-pixel sampling methods for high-accuracy strain distribution measurements at the micro/nano-scale is presented here.

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. ...