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Title:

REACTIONS ACCOMPANYING STABILIZATION OF CLAY WITH CEMENT

Accession Number:

00230508

Record Type:

Component

Abstract:

RESULTS ARE REPORTED OF AN INVESTIGATION DESIGNED TO DELINEATE THE NATURE OF THE REACTIONS ACCOMPANYING THE STABILIZATION OF CLAY WITH PORTLAND CEMENT. IT HAS BEEN POSTULATED THAT THE HARDENING OF A CLAY-CEMENT MIXTURE INVOLVES ALTERATION OF CLAY MINERAL STRUCTURES AND AMORPHOUS CONSTITUENTS RESULTING IN THE FORMATION OF SECONDARY CEMENTITIOUS MATERIAL IN ADDITION TO THE USUAL HYDROLYSIS AND HYDRATION OF THE CEMENT WHICH MAY BE REGARDED AS PRIMARY STABILIZED REACTIONS. THE RESULT OF MECHANICAL, X-RAY DIFFRACTION, AND CHEMICAL TESTS ALL TENDED TO SUPPORT THIS HYPOTHESIS. THE MOST SIGNIFICANT RESULTS THAT MAY BE DRAWN FROM EXPERIMENTAL WORK ARE' /1/ VERY EFFECTIVE STABILIZATION OF BOTH KAOLINITE AND MONTMORRILLONITE WAS OBTAINED USING BOTH NORMAL PORTLAND CEMENT AND A PURE TRI-CALCIUM SILICATE COMPOUND AS REFLECTED BY THE COMPRESSIVE STRENGTH OF SPECIMENS SOAKED FOR 24 HOURS AFTER CURING FOR SPECIFIED PERIODS, /2/ SPECIMENS MADE FROM NEAT C3S PASTE HAD ONLY A FRACTION OF THE STRENGTH OF SPECIMENS OF NEAT PORTLAND CEMENT, HOWEVER, CLAY-C3S SPECIMENS WERE ALWAYS STRONGER THAN CLAY- PORTLAND CEMENT SAMPLES, SUGGESTING A MODIFICATION OF THE C3S HYDRATION PROCESS IN THE PRESENCE OF CLAY MINERALS. HYDRATED C3S IS THE MAIN CONTRIBUTOR TO THE STRENGTH OF HARDENED PORTLAND CEMENT, /3/ X-RAY DIFFRACTION STUDIES OF HYDRATING CLAY-CEMENT MIXTURES SHOWED THAT PORTLAND CEMENT FORMED CALCIUM HYDROXIDE IN HYDRATING CLAY-CEMENT. THE HYDRATION OF C3S WAS MODIFIED IN THE PRESENCE OF CLAY. AFTER 1-WEEK CURING NO CRYSTALLINE CALCIUM HYDROXIDE WAS DETECTABLE IN CLAY-CEMENT SPECIMENS. SMALL DECREASES IN THE INTENSITY OF KAOLINITE REFLECTIONS AND LARGE DECREASES IN THE INTENSITY OF MONTMORILLONITE REFLECTIONS WERE OBSERVED AFTER 12 WEEKS CURING OF CLAY-CEMENT, AND NEW LINES OF LOW INTENSITY WERE OBSERVED IN SOME CLAY-CEMENT PATTERNS AFTER LONG CURING TIMES, SUGGESTING THE FORMATION OF NEW CRYSTALLINE REACTION PRODUCTS, /4/ THE PH OF HYDRATING NEAT PORTLAND CEMENT, HYDRATING NEAT C3S, AND BLANK CLAY SPECIMENS REMAINED CONSTANT WITH TIME BUT DECREASED MARKEDLY DURING THE CURING OF CLAY-CEMENT MIXTURES INDICATING THE EXISTENCE OF AN /OH/ NEGATIVE CONSUMING PROCESS, /5/ CONDUCTIVITY VALUES OF CLAY-CEMENT EXTRACTS INDICATE A SIGNIFICANTLY LOWER ELECTROLYTE CONTENT THAN WOULD BE EXPECTED IF THE CEMENT HYDRATED WITHOUT INTERACTION WITH THE CLAY, SUGGESTING THAT IN CLAY-CEMENT THE SOLUBLE SALTS FORMED BY CEMENT HYDRATION ARE CONVERTED TO LESS SOLUBLE COMPOUNDS WHICH MAY SERVE TO BOND PARTICLES, /6/ THE ACTUAL EXTRACTABLE CALCIUM CONTENTS OF ALL CLAY- CEMENT MIXTURES WERE SIGNIFICANTLY LOWER THAN VALUES COMPUTED ON THE ASSUMPTION OF NO CLAY-CEMENT INTERACTION, /7/ ALL CLAY-CEMENT SPECIMENS CONTAINED ONLY A FRACTION OF THE FREE CALCIUM HYDROXIDE THAT WOULD BE PRESENT IF

Supplemental Notes:

Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

Monograph Title:

Cement-treated soil mixtures

Monograph Accession #:

01410006

Language:

English

Authors:

Herzog, A
Mitchell, J K

Pagination:

pp 146-171

Publication Date:

1963

Serial:

Highway Research Record

Issue Number: 36
Publisher: Highway Research Board

Media Type:

Print

Features:

Appendices (1) ; Figures (18) ; References (22) ; Tables (4)

Old TRIS Terms:

Subject Areas:

Bridges and other structures; Geotechnology; Highways; Safety and Human Factors

Files:

TRIS, TRB

Created Date:

Aug 15 2004 2:40AM

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