EN 14679:2005

Execution of special geotechnical works - Deep mixing

This document specifies general principles for the execution, testing, supervision and monitoring of deep mixing works carried out by two different methods: dry mixing and wet mixing.
Deep mixing considered in this document is limited to methods, which involve:
a)   mixing by rotating mechanical mixing tools (see Annex A, Figure A.1) where the lateral support provided to the surrounding soil is not removed;
b)   treatment of the soil to a minimum depth of 3 m;
c)   different shapes and configurations, consisting of either single columns, panels, grids, blocks, walls or any combination of more than one single column, overlapping or not (see Annex A, Figures A.8 to A.12);
d)   treatment of natural soil, fill, waste deposits and slurries, etc.;
e)   other ground improvement methods using similar techniques exist (see A.3.5).
Guidance on practical aspects of deep mixing, such as execution procedures and equipment, is given in Annex A. Main applications are exemplified in Annex A, Figure A.14. Methods of testing, specification and assessment of design parameters, which are affected by execution, are presented in Annex B.

Ausführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - Tiefreichende Bodenstabilisierung

Dieses Dokument legt die allgemeinen Grundlagen für die Ausführung, Kontrolle, Überwachung und Aufzeich-nung der tiefreichenden Bodenstabilisierung fest, wobei zwischen zwei verschiedenen Verfahren unterschieden wird: das Trockenmischverfahren und das Nassmischverfahren.
Die tiefreichende Bodenstabilisierung ist nach diesem Dokument auf Verfahren mit folgenden Eigenschaften beschränkt:
a)   Mischung durch rotierende mechanische Mischwerkzeuge (siehe Anhang A, Bild A.1), wobei die horizontale Stützung durch den umgebenden Boden nicht beseitigt wird;
b)   Behandlung des Bodens bis in eine Tiefe von mindestens 3 m;
c)   unterschiedliche Geometrien und Anordnungen, bestehend aus einzelnen Säulen, Mehrfachelementen, Rastern, Blöcken, Wänden oder Kombinationen von mehr als einer Einzelsäule, überschnitten oder allein stehend (siehe Anhang A, Bilder A.8 bis A.12);
d)   Behandlung von gewachsenem Boden, Auffüllung, Müllablagerungen und Schlämmen usw.;
e)   andere Bodenverbesserungsverfahren, die ähnliche Techniken verwenden (siehe A.3.5).
Hinweise zu praktischen Aspekten der tiefreichenden Bodenstabilisierung betreffend Ausführungstechniken und Ausrüstung werden in Anhang A gegeben. Hauptanwendungen werden in Anhang A, Bild A.14 veranschaulicht. Prüfverfahren und die Beschreibung und Festlegung von Bemessungsparametern werden in Anhang B vorgestellt, soweit sie durch die Ausführung beeinflusst werden.

Exécution des travaux géotechniques spéciaux - Colonnes de sol traité

La présente Norme européenne établit les principes généraux relatifs à l'exécution, aux essais de contrôle, à
la surveillance et au suivi des travaux de colonnes de sol traité réalisés selon la technique de malaxage par
voie sèche ou selon la technique de malaxage par voie humide.
Les colonnes de sol traité, concernées par la présente norme, sont celles qui s�inscrivent dans le cadre défini
ci-après :
a) le mélange est effectué au moyen d'outils rotatifs mécanique de malaxage (voir l'Annexe A, Figure A.1), le
sol environnant latéral étant constamment maintenu pendant l�opération ;
b) le traitement du sol est réalisé sur une hauteur minimale de 3 m ;
c) la réalisation de différentes formes et configurations, comprenant des colonnes simples, des panneaux,
des grilles, des massifs, des parois ou toute autre combinaison d'au moins deux colonnes simples, se
recoupant ou non (voir l'Annexe A, Figures A.8 à A.12) ;
d) le traitement de sol naturel, de remblai, de dépôts d�ordures et de déchets, etc. ;
e) il existe d�autres méthodes d'amélioration du sol utilisant des techniques similaires (voir A.3.5).
Des informations pratiques relatives à la réalisation des colonnes de sol traité, comme les procédures
d�exécution et les matériels, sont données en Annexe A. Les méthodes d'essais et d'évaluation des
paramètres de conception, qui intéressent l'exécution, sont présentées en Annexe B.

Izvedba posebnih geotehničnih del – Globinsko mešanje

General Information

• Status: Published
• Publication Date: 12-Apr-2005
• Withdrawal Date: 12-Oct-2005
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: CEN/TC 288 - Execution of special geotechnical works
• Drafting Committee: CEN/TC 288/WG 10 - Deep soil mixing
• Current Stage: 9092 - Decision on results of review/2YR ENQ - revise - Review Enquiry
• Start Date: 17-Jul-2020
• Completion Date: 14-Apr-2025
• Ref Project: SIST EN 14679:2005 - Execution of special geotechnical works - Deep mixing

Relations

• Corrected By: EN 14679:2005/AC:2006 - Execution of special geotechnical works - Deep mixing
• Effective Date: 22-Dec-2008
• Revised: prEN 14679 - Execution of special geotechnical works - In-Situ Soil Mixing
• Effective Date: 19-May-2021

Overview

EN 14679:2005 - Execution of special geotechnical works - Deep mixing (CEN) sets out the general principles for the execution, testing, supervision and monitoring of deep mixing ground improvement works. The standard covers deep mixing carried out by two principal methods: dry mixing (mechanical disaggregation and dry binder addition) and wet mixing (mixing with liquids or cementitious slurries). Deep mixing in this standard is limited to operations using rotating mechanical mixing tools, treating soils to a minimum depth of 3 m, and producing elements such as single columns, panels, grids, blocks or walls. Treatments may be applied to natural soils, fills, waste deposits and slurries.

Key topics and requirements

• Scope & methods: Defines deep mixing methods (dry vs wet), mixing tools and typical element configurations (columns, overlapping patterns).
• Geotechnical investigation: Information required before execution, including site-specific soil data and parameters that influence binder choice and mixing strategy.
• Materials & binders: Guidance on binder types (lime, cement, slag, fly ash, admixtures) and considerations for dosing (binder content/factor) and fillers.
• Design considerations: Factors affected by execution, requirement for laboratory and in-situ mixing tests, and preparation of a design statement.
• Execution controls: Method statements, site preparation, field trials, execution tolerances, mixing energy and blade rotation monitoring.
• Quality assurance & testing: Supervision, field and laboratory testing, monitoring of treated soil performance, and record-keeping during and after construction.
• Practical guidance: Annex A gives practical execution procedures, equipment illustrations and common installation patterns. Annex B addresses testing methods and assessment of design parameters.

Applications and users

Practical applications of deep mixing per EN 14679 include:

• Ground improvement for foundations and embankments
• Strengthening of weak or compressible soils and waste deposits
• Treatment of contaminated or slurry soils where in-situ mixing is required
• Construction of cutoff walls, load-bearing columns and retaining elements

Primary users:

• Geotechnical and structural engineers (design and specification)
• Groundworks and specialist deep mixing contractors
• Site supervisors and QA/QC engineers
• Testing laboratories and materials suppliers
• Clients and regulators specifying ground improvement works

Related standards

EN 14679 is intended to complement Eurocode and related documents, for example:

• EN 1997-1 / prEN 1997-2 (Eurocode 7 geotechnical design)
• EN 12716 (Jet grouting execution)
• Cement and binder test standards (EN 196 series, EN 197)
• Soil/rock classification standards (EN ISO 14688, EN ISO 14689)

EN 14679 is a practical reference for standardizing deep mixing, ensuring reliable ground improvement, consistent testing and documented quality control across projects.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Execution of special geotechnical works - Deep mixingExécution des travaux géotechniques spéciaux - Colonnes de sol traitéAusführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - Tiefreichende Bodenstabilisierung93.020Zemeljska dela. Izkopavanja. Gradnja temeljev. Dela pod zemljoEarthworks. Excavations. Foundation construction. Underground worksICS:SIST EN 14679:2005enTa slovenski standard je istoveten z:EN 14679:200501-oktober-2005SIST EN 14679:2005SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14679April 2005ICS 93.020English versionExecution of special geotechnical works - Deep mixingExécution des travaux géotechniques spéciaux - Colonnesde sol traitéAusführung von besonderen geotechnischen Arbeiten(Spezialtiefbau) - Tiefreichende BodenstabilisierungThis European Standard was approved by CEN on 28 February 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2005 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14679:2005: E

Practical aspects of deep mixing.22

Aspects of design.38 B.1 General.38 B.1.1 Scope.38 B.1.2 Application.38 B.2 Design principles.39 B.3 Execution process of deep mixing.40 B.4 Choice of binder.41 B.5 Testing.41 B.5.1 General.41 B.5.2 Laboratory testing.41 B.5.3 Field testing.43 B.6 Correlation of various properties of treated soil.44 B.6.1 Field strength and laboratory strength.44 B.6.2 Correlation between mechanical characteristics and unconfined compressive strength.46 B.7 Aspects of design.46 B.7.1 Stability.46 B.7.2 Settlement.49 B.7.3 Confinement.49 Annex C (informative)
Degree of obligation of the provision.50

Principles for a classification (ISO 14688-2:2004) EN ISO 14689-1, Geotechnical investigation and testing — Identification and classification of rock — Part 1: Identification and description (ISO 14689-1:2003). 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 admixture fr: additif, addition de: Zusatzmittel dispersant, fluidifier, retarding agent 3.2 binder fr: liant de: Bindemittel chemically reactive materials (lime, cement, gypsum, blast furnace slag, fly ash, etc.) 3.3 binder content fr: teneur pondéral en liant de: Bindemittelgehalt weight of dry binder introduced per unit volume of soil to be treated 3.4 binder factor fr: dosage volumique de liant de: Bindemittelfaktor ratio of the weight of dry binder introduced to the dry weight of the soil to be treated 3.5 blade rotation number fr: nombre de rotation d'aile de: Flügelumdrehungszahl total number of mixing blade rotations per m of shaft movement.

EN 791 and EN ISO 14689-1). 5.1.3 Relevant experience of the execution of comparable deep mixing works under similar conditions in the vicinity of the site shall be taken into account when determining the extent of the site investigation. 5.1.4 The site investigation report shall be made available together with all relevant data known to affect the choice of method. 5.1.5 Boreholes or trial pits shall be suitably sealed not to affect groundwater movement and/or subsequent deep-mixed column construction and performance. 5.2 Specific information 5.2.1 Identification and classification of soil shall comply with EN ISO 14688-1 and EN ISO 14688-2. 5.2.2 Apart from the general geological description and the details listed in EN 1997-1, the site investigation report shall contain the following information regarding ground conditions for the execution of deep mixing: a) the composition, lateral extent, thickness and firmness of the surface stratum, tree roots, fill, etc.; b) presence of cobbles or boulders, cemented layers or underlying rock that can cause difficulties for the execution or could require special methods or tools;

Current penetration or retrieval rates of mixing shaft are usually 10 mm/rev to 50 mm/rev and the blade rotation numbers are usually 200 to 500. NOTE 2 The amount of mixing work involved in producing a dry-mixed column depends on the type and quantity of binder and type of soil. Cement as binder requires a higher mixing energy than lime only. 8.6.2.4 In dry mixing the air pressure shall be kept as low as possible during the mixing process to avoid problems of air entrainment and ground movements. NOTE If the air pressure is too low, the binder may not spread into the whole cross-sectional area of the column. 8.6.2.5 The amount of binder and the air pressure shall be monitored during installation of the columns. 8.6.2.6 Mixing energy should be monitored to achieve uniform treated soil. 8.6.3 Wet mixing 8.6.3.1 The execution procedure of wet mixing shall take into account the specifications given in the design.
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