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California Test 404STATE OF CALIFORNIA—BUSINESS, TRANSPORTATION AND HOUSING AGENCY August 1998

DEPARTMENT OF TRANSPORTATIONENGINEERING SERVICE CENTERTransportation Laboratory5900 Folsom BoulevardSacramento, California 95819-4612

METHODS OF TEST FOR THE CHEMICALANALYSIS OF PORTLAND CEMENT,

FLY ASH, POZZOLAN, AND BLENDED CEMENT

CAUTION: Prior to handling test materials, performing equipment setups, and/or conducting thismethod, testers are required to read “SAFETY AND HEALTH” in Part 3 of thismethod. It is the responsibility of the user of this method to consult and usedepartmental safety and health practices and determine the applicability of regulatorylimitations before any testing is performed.

SCOPE

This test method is divided into thefollowing parts:

1. Determination of Major Constituents ofPortland Cement

2. Determination of Chlorides

3. Safety and Health

PART 1. DETERMINATION OF MAJOR CONSTITUENTS OF PORTLAND CEMENT

The procedures used in the chemical analysisof portland cement are described in this groupof tests. For routine samples, the atomicabsorption method is used. For refereesamples, or samples where there is a questionas to the results, the official methodsdescribed in ASTM Designation: C 114 areused.

A. APPARATUS

1. Unless otherwise indicated, all reagentsshall conform to the specifications of theCommittee on Analytical Reagents of theAmerican Chemical Society (where suchspecifications are available).

2. Atomic Absorption Spectrophotometer -(AAS) - The Perkin-Elmer AAnalyst 100has been found to be satisfactory.

3. Carbon and Sulfur Analyzer - The LECOCorp. Model CS-225 induction furnacehas been found satisfactory.

B. PROCEDURE

Before testing, pass samples through a850-µm sieve in order to mix the sample,break up lumps and remove foreign materials.Discard foreign materials and hardenedlumps that do not break up on sieving orbrushing. Store the cement in airtightmoisture proof containers to prevent aerationor absorption of moisture prior to test.

1. Rapid Chemical Analysis Method:

The determination of oxides of silica,aluminum, iron, calcium, magnesium,sodium and potassium using an atomicabsorption spectrophotometer and that ofsulfur trioxide using the LECO inductionfurnace are described in the method.

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a. Selection of National Institute ofStandards and Technology (NIST)Standards:

Select a series of at least fourstandard cement samples that willbracket the expected concentrations ofthe elements in the unknown samples.

b. Preparation of Standards:

Weigh 0.250 g of NIST standardcement into a 100-mL beaker.Disperse with 20 mL of distilledwater and 4 mL of concentratedhydrochloric acid. Break up lumps ofcement with a rubber policeman orglass stirring rod, rinse and removethe policeman or rod from the beaker.Cover the sample with a watch glassand digest the sample on a low hotplate for 15 min at approximately75˚C. During digestion, continuouslystir the sample. An oscillating hotplate is preferred for this process.Filter through a medium-texturefilter paper into a 200-mL volumetricflask, scrubbing the beaker with arubber policeman. Wash the samplethoroughly with hot hydrochloricacid (1:99), then with several rinsesof hot distilled water. Cool thesample to room temperature, thendilute to a volume of 200 mL. It isrecommended that new standards bemade up each month.

c. Preparation of Samples:

Weigh 0.125 g of cement into a 100-mLbeaker. Disperse it with 10 mL ofdistilled water and 2 mL ofconcentrated hydrochloric acid.Digest and prepare the sampleexactly as described in Section b,“Preparation of Standards.” Thefinal filtrate is diluted to a volume of100 mL.

For the determinations of calciumoxide and magnesium oxide, a portionof the solutions prepared in Sections b

and c are diluted to 1 to 10 with thefinal dilution containing 0.5 % oflanthanum, which is found to beeffective for the suppression ofchemical interferences. Standardsare diluted similarly.

d. Preparation of Fly Ash, Pozzolan,and Blended Cement Samples:

Follow the procedures as described inASTM Designations: C 311 and C 595,except modify the fusion procedure asfollows. A quantity of the ignitedsample, equivalent to 0.250 g of themoisture free sample, is mixed with1.5 g of an equal mixture of Li 2B4O7

and LiBO2. The fusion procedure

is described in ASTM Designation:E 886. The fused mixture is thendissolved in 80 mL of 1:8 hothydrochloric acid. The resultingsolution is filtered and finallydiluted to 200 mL. NIST standardsfor calibration are prepared in thesame way.

e. Sulfur Trioxide Determination Usingan Induction Furnace:

Follow the manufacturer's recom-mendations. The following has beenfound to be a satisfactory methodusing a LECO induction furnace.

Weigh a 0.15 g sample into acombustion crucible. Add one scoop ofLecocel and one scoop of iron chipaccelerator. Follow the instrumentmanufacturer’s directions for thisanalysis. Standardize the instrumentwith NIST cement standards usingthe same procedure as describedabove.

2. Reference Analysis

For silica, ammonium hydroxide group,aluminum oxide, ferric oxide, calciumoxide, magnesium oxide, sulfur trioxide,ignition loss, insoluble residue, sodiumoxide and potassium oxide, followASTM Designation: C 114.

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PART 2. DETERMINATION OF CHLORIDES

This part describes a procedure for deter-mining chlorides in portland cement andportland cement concrete.

A. APPARATUS

1. Chloride specific ion electrode

2. Double junction reference electrode

3. Millivoltmeter compatible with theelectrodes

B. PROCEDURE

1. Weigh 2.0 to 5.0 g of portland cement intoa 400-mL breaker.

2. Add 100 mL of boiling water.

3. Add a slight excess of 0.1 Normal silvernitrate from a buret (5 mL is anapproximate amount of silver nitrate forcement that contains no more than 0.15 %chloride). Record the amount added.

4. Boil the sample for two minutes, removeit from the heat, then cool it slightly.

5. Slowly add 20 mL of concentrated nitric

acid, efflorescence will often occur.

6. Heat and break up any lumps ofundissolved cement with the flattenedend of a stirring rod, cover the sample andboil it for 2 min.

7. Filter through a medium speed (90-mm“OK” is satisfactory) paper in a Buchnerfunnel with suction. The filtrate shouldbe clear. Add approximately 1 g ofdiatomaceous earth to aid filtering ifdesired.

8. Wash the residue three times with 1:99nitric acid. Discard the residue.

9. Quantitatively transfer the filtrate to a400-mL beaker and cool it to roomtemperature.

10. Carry three standards through the testprocedures with the same amount of acidand silver nitrate but without cement.

11. Adjust all standards and samples toapproximately equal volume withdistilled water to eliminate blankdetermination.

12. Titration of Samples:

a. Titration using a ferric ion indicator.With cements that are low in iron,add a few drops of ferric ironindicator (5 g of ferric ammon-ium sulfate dissolved in 50 mL of 1 Normal nitric acid). Titratewith 0.05 Normal ammoniumthiocyanate that has been stand-ardized against the silver nitratestandards to the first permanent redcolor. Use burets with 0.05-mLgraduations and make all readingscarefully to the nearest 0.01 mL.

b. Titration with a specific ionelectrode. Following the manu-facturer's recommendation for the useof specific ion electrode, titrate thesamples with the 0.05 Normalammonium thiocyanate that has beenstandardized against the silvernitrate standards prepared inStep 10. Plot a curve of the change inpotential against volume ofthiocyanate to find the end point.

13. Calculate chlorides by the followingformula:

% chlorides = [(A x N) - (B x M)] x F x100/mass of the sample, to thenearest 1g

Chlorine (ppm) = % x 10 000

Where A = mL of AgNO3

N = Normality of the AgNO3

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B = mL of NH4SCNM = Normality of the NH4SCNF = conversion factor to Cl,

or 0.03546

PART 3. SAFETY AND HEALTH

This method may involve hazardousmaterials, operations and equipment. Thismethod does not purport to address all thesafety problems associated with its use. It isthe responsibility of the user of this methodto consult and establish appropriate safetyand health practices and determine theapplicability of regulatory limitations priorto use. This method involves the handling ofhazardous chemicals and samples,compressed and flammable gases, andsophisticated instruments which can bedangerous.

Prior to handling testing or disposing of anywaste materials, testers are required to readthe Caltrans Laboratory Safety Manual

These guidelines pertain to requirements forgeneral safety principles, standard operatingprocedures, protective apparel, disposal ofmaterials and how to handle spills,accidents, emergencies, etc. Testers aremandated to always observe good hygienepractices. Wash hands after handlingsamples and before eating, drinking orsmoking. Users of this method do so at theirown risk.

REFERENCES:Caltrans Lab Safety Manual

ASTM Designation: C 114AASHTO Designation: T 105

Portland Cement Association, ResearchDepartment Bulletin 214, “Analysis of Portland

Cement by Atomic Absorption.”

End of Test (California Test 404 contains 4 pages)