Publications

Thesis

Jaquin, P. A. Analysis of historic rammed earth construction. Durham University, 2008

Rammed earth is an ancient construction technique which has recently become popular for sustainable building. Soil is compacted in removable formwork to make a homogeneous wall. A lack of experimental evidence and a poor fundamental understanding means that current design guidelines are highly conservative and inappropriate for the analysis of historic rammed earth buildings. This thesis shows that rammed earth can be viewed in a geotechnical engineering framework and that doing so helps to explain many aspects of the material behaviour. Rammed earth walls were built and tested in the laboratory then modelled using techniques available to practising engineers. Unsaturated soil mechanics was considered useful in explaining much of the behaviour of rammed earth. This was investigated through a series of uniaxial compression tests and the results are explained using unsaturated soil mechanics. Visits to Spain and India were made to investigate rammed earth in the field. Historic construction techniques, modes of failure and repair strategies were studied. The unsaturated nature of rammed earth is used to explain modes of failure and to suggest the most appropriate repair strategies.

Details available here.

Journal publications

Jaquin, P. A., Augarde, C. E., Gallipoli, D. and Toll, D.G. The strength of rammed earth materials. Geotechnique

Rammed earth is a manufactured material comprising sand, gravel and clay, which is compacted between forms to build walls. Primarily a historic method of construction, it is now receiving considerable interest worldwide owing to its zero reliance on materials such as cement, and its potential for recycling. Despite its longevity, the source of its shear strength is poorly understood. This paper presents initial laboratory test results that point to the main source of strength in rammed earth being suction, and indicating that recent advances in unsaturated soil mechanics may also be applied to this material.

Jaquin, P.A. Augarde, C.E. Gerrard, C.M. Historic rammed earth distribution. International Journal of Architectural Heritage

Rammed earth has been used by man for thousands of years and is currently experiencing a revival in some parts of the world as a result of its inherent sustainability. Historic rammed earth structures are scattered around the world, and much information can be derived from these structures to inform the development of modern rammed earth. This article provides a chronological study of rammed earth distribution through observation of monumental build- ings to aid the study of this building technique. It is shown that the rammed earth technique is 10 likely to have originated independently in China and around the Mediterranean, and spread through the movement of people and ideas to many other parts of the world. Through observation of historic rammed earth sites, geographic and climatic limits can be placed on the extent of rammed earth. The different ways rammed earth has been used over time are explored, culminating in its current incarnation as a sustainable building material.

Please contact me if you would like a copy of these academic journal publications

Jaquin, P. A. Study of historic rammed earth structures in Spain and India. The Structural Engineer

The Rowen Travel Award was granted for the study of historic rammed earth structures in Spain and India. Eight locations in northern Spain and three in northern India were visited during October and November 2006. The object of the visits was to gain a greater understanding of historic rammed earth. Methods of construction, modes of failure and repair techniques were investigated. Use of rammed earth as a modern building material is increasing, and the study of historic structures can inform development of the technique today. A number of examples which are considered to be of interest to practicing engineers are presented. The examples deal with the presence of water in earthen structures, cracking and methods of crack repair, the facing of rammed earth with a less permeable material, and medieval seismic protection measures. This work forms part of a PhD looking into the analysis and conservation of historic rammed earth structures, with field visits being a major aspect of the study.

  (1.52MB) Study of historic rammed earth structures in Spain and India

Conference proceedings

Papers

Hardwick, J., Jaquin, P.A. Seismic performance of mud brick structures. Engineers without Borders research conference. London. 19 Febuary 2010

Jaquin, P.A. How Mud Bricks Work- Using Unsaturated Soil Mechanics Principles to Explain the Material Properties of Earth Buildings - A year of research. Engineers without Borders research conference. London. 19 Febuary 2010

Jaquin, P.A.,Gerrard, C.M., Augarde, C.E. and Canivell, J. Damage in Historic Rammed earth structures: A case study at Ambel, Zaragoza, Spain. SIACOT IX. Coimbra, Portugal. 20-23 February 2010.

This paper examines the possible causes of damage to historic rammed earth structures based on a case study of a medieval and later building, formerly a preceptory of the Military Orders, in the village of Ambel in Aragon, north-east Spain. Structural and water-based mechanisms of damage are reviewed and an engineering basis for the cause of damage is proposed. Since a number of repair strategies have already been attempted on this structure, their effectiveness is also discussed. A four storey granary at the north-east corner of the preceptory complex is described in detail since it encapsulates many damage mechanisms and repair strategies which are common to historic rammed earth. The granary tower has a random rubble foundation, which is probably in part the remains of previous building, with rammed earth walls for the three storeys above. This rammed earth was originally rendered and scored to imitate fired brick but almost all of this has now fallen away. The gable end of the building has fired brick quoins, and now leans outwards slightly at the head of the wall. There is evidence of water damage because the building was neglected in the past, though not enough to initiate collapse. Structural and water based damage mechanisms are identified, and example repair strategies used at Ambel are described.

  (421KB)  Damage in Historic Rammed earth structures: A case study at Ambel, Zaragoza, Spain

Canivell, J., Jaquin, P.A., Augarde, C.E. and Gerrard, C.M. Sistemas de Reparacion en Fabricas Historicas de Tapial. SIACOT IX. Coimbra, Portugal.20-23 February 2010.

Jaquin, P.A. Humidity regulation in earth buildings. Ramboll Technical Forum. London November 2009.

Earth buildings (for example sun dried mud bricks, rammed earth and cob) are known to control internal relative humidity. There is an optimum relative humidity range within which humans operate best, if the relative humidity is too high, then a space feels hot and stuffy, if the relative humidity is too low, this tends to dry the eyes and throat. Some benefits of keeping relative humidity within a specific range are given. Museums and art galleries require a constant relative humidity to preserve historic artefacts. This paper defined relative humidity and outlines the mechanisms by which earth buildings regulate relative humidity. Two types of relative humidity regulation are described, balancing and buffering, and a qualitative descriptions of each process discussed. Ongoing research work at the University of Bath is described, which will enable the quantification of these processes such that earth building elements may be designed by engineers to achieve humidity balancing within a building.

  (454KB)  Humidity regulation in earth buildings paper

  (2.42MB)  Humidity regulation in earth buildings poster

Jaquin, P. A., Augarde C.E and Legrande, L. Unsaturated characteristics of rammed earth. First European Conference on Unsaturated Soils, Durham, July 2008

Rammed earth is both an ancient construction technique and the name for the material produced by the technique. Rammed earth is gaining in popularity around the world due to its ecological and sustainable attributes. Walls of rammed earth are formed by taking a graded mixture of (usually) locally-won soil and compacting the mixture between formwork in a similar manner to concrete. The formwork is then removed leaving a solid earth wall. There is little scientific understanding of the source of strength in rammed earth and design to date has used empirical approaches. In this paper we consider rammed earth as an unsaturated soil thus explaining one source of strength to be from suction. Laboratory tests have been carried out on rammed earth samples including unconfined compression and Brazilian tests (to measure strength) and filter paper tests (to determine the water retention properties). The tests all indicate that a source of strength in rammed earth derives from suction and conclusions are drawn as to their levels in ancient rammed earth structures.

Jaquin, P.A., Augarde, C. E. and Gerrard, C.M. Historic Rammed Earth Structures in Spain. International Symposium on Earthen Structures, Bangalore, August 2007

Conservation and repair of historic rammed earth sites should only be undertaken if there is a good understanding of the consequences of any intervention technique. Until recently there has been little interest in the characterisation of historic rammed earth construction, yet it is only with this understanding that successful conservation strategies can be adopted. A survey of around 60 historic rammed earth sites in Spain constructed between 967AD and 1837AD has recently been undertaken. While all the sites are built primarily in rammed earth, the construction techniques and state of repair vary greatly. The high density of historic rammed earth structures in the Iberian peninsula is likely due to the Muslim presence there from the 8th century onwards. Initial expansion, a period of civil war and eventual defeat by Christians led to the construction of a large number of fortifications, many constructed in rammed earth. A famous example is the Alhambra at Granada, but there are hundreds of smaller sites throughout Spain. By the end of the 15th century Christians had replaced Muslims through most of Spain, but rammed earth continued to be used in both vernacular and monumental architecture. Examples of historic construction techniques are presented and common features of historic rammed earth construction are identified. A classification is outlined and a clear development of the rammed earth technique is observed.

  (1.40MB)  Historic Rammed Earth Structures in Spain

Jaquin, P.A., Analysis of Historic Rammed Earth Construction. 9th Young Geotechnical Engineers Symposium, Belfast, September 2006

Rammed earth is an ancient construction technique used in many parts of the world. Soil is taken from the ground and poured into formwork similar to modern concrete, then compacted using a hand rammer to form a solid mass, the formwork is then removed leaving a solid wall. Long sections of the Great wall of China, parts of the Potala Palace in Lhasa, and ancient structures in Spain and Morocco (Figure 1) are all built in rammed earth. It has recently seen a revival as a new building technique because of its low carbon emission and high sustainability (Figure 2). The aim of this project is to increase the understanding of the construction material rammed earth such that structures built in rammed earth can be better analysed and conserved. The project arises from the lack of engineering knowledge available to conservators of rammed earth structures [1], and the lack of understanding of the fundamental processes at play in rammed earth. By taking a new approach of treating rammed earth as a soil rather than as a structural engineering material (as concrete or masonry) we are able to better understand and predict the properties of the material.

  (1.12MB)  Analysis of Historic Rammed Earth Construction

Jaquin, P. A., Augarde, C. E. and Gerrard, C.M. Analysis of Historic Rammed Earth Construction. Structural Analysis of Historic Constructions, New Delhi, November 2006

Rammed earth is a widely used historic building material, found in Mediterranean regions, along the Silk Road, and in parts of the Himalayas. While guidlines exist for the construction of new rammed earth structures, there is little guidance for the structural analysis of historic structures.

A novel approach to the modelling of rammed earth using finite elements is presented. Each rammed earth lift is modeelled as two layers, one representing the actual rammed earth and one representing the interface between each rammed earth lift. These layers are both modelled using the Mohr-Coulomb failure criterion, but different strength properties are assigned to earch. A rammed earth wall is then built up using a number of these layers. These simulations have been compared with rammed earth test walls constructed in the laboratory and the above technique has been used to model these walls, with a good degree of sucess.

  (1.07MB)  Analysis of Historic Rammed Earth Construction

Jaquin, P. A., Augarde, C. E. and Gerrard, C.M. Analysis of Tapial structures for modern use and conservation. Structural Analysis of Historic Constructions, Padova, November 2004

Tapial is an ancient form of rammed earth wall construction found in many parts of the world. In medieval Spain, Tapial was used in the construction of some very large and complex structures, some many-storied. That these buildings remain standing (many remaining also in use) is an indication of the dura-bility of this form of construction, and is perhaps related to the climatic conditions found in central Spain. This paper describes an engineering study into an important structure in the Aragon region, significant parts of which are constructed in medieval Tapial, as well as adobe and other forms of construction. The aim of the study is both to improve understanding of the nature of this structure and to provide guidance on methods of preservation and new construction.

  (3.46KB)  Analysis of Tapial structures for modern use and conservation

Posters

Jaquin, P. Development and spread of the rammed earth technique. Lehm 2008, Koblenz, Germany, October 2008

(1.44MB)  Development and spread of the rammed earth technique

Jaquin, P. Analysis of Historic Rammed Earth Structures Presentations by Britain's Top Younger Scientists and Engineers, Houses of Parliament, London, October 2006

(1.24MB)  Analysis of Historic Rammed Earth Structures

Jaquin, P. Historic Rammed Earth Construction Institution of Structural Engineers Young Researchers Conference, London, September 2006

(1.32MB)  Historic Rammed Earth Construction

Articles

Link found between sand castles and rammed earth structures. New Civil Engineer. 3 June 2009

Sandcastles hold key to Great Wall of China building technique. Daily Telegraph. 3 June 2009

Sandcastles share secret of green construction. Building magazine. 3 June 2009

Sandcastle study for eco-building. BBC News online. 3 June 2009

'Sandcastle' key to green future. The Scotsman. 4 June 2009

Durham University scientists examine sandcastles. The Northern Echo. 4 June 2009/

Jaquin, P. 2007 Rammed earth floors. Green Building Magazine, 17 (3) Green Building Press.

Interviews

Jaquin, P. Maggaly Ruiz, Earth building in Colombia and the UK May 2007

Jaquin, P. Rammed Earth is for Everyone July 2006

Photograph credits

Checkerboard Films. Film on architect Rick Joy. December 2009

Corriere della sera. Italian magazine. July 2009.

Grains de bâtisseurs, a 5 year exhibition at Cité des sciences et de l'industrie, Paris. Interpretive panels and accompanying book. March 2009

Interpretive Panels, McConnell Foundation Sustainability Gardens, Turtlebay Educational Centre, Redding California. October 2009

Two photographs on Schmap.com interactive maps and guides. June 2008

World Heritage, magazine with the UNESCO World Heritage Centre. Terra 2008 Conference edition. November 2007

Two historic rammed earth building photographs in Easton, D. The Rammed Earth House. Chelsea Green Publishing Company. Reprinted August 2007

Abenteuer und Reisen. German Travel magazine. September 2007

Tunza United Nations Environment Program magazine. July 2007

Two photographs of historic rammed earth buildings used in Desert Living Center in Las Vegas, showing the history and development of the rammed earth technique. For Aldrich Pears.

Presentations

How earth buildings regulate relative humidity. November 2009. Ramboll Technical Forum. London.

Rammed earth for engineers. 15 September 2009. Internal Ramboll Presentation. Bristol

The Science of Sandcastles. 5 September 2009. Orkney International Science Festival. Kirkwall.

How to make mud bricks. 7 February 2009. Engineers without Borders course. London

Rammed earth. 6 August 2008. Ramboll Whitbybird Technical Highlight. London

Rammed earth. 28 July 2008. Ramboll Whitbybird Lunchtime seminar . Edinburgh

Unsaturated characteristics of rammed earth 4 July 2008. 1st European Conference on Unsaturated Soils

School of Engineering Research Day 25 June 2007 - Soil Mechanics group presentation

Rammed earth. Eden Valley Green week. September 2007

Advanced Mechanics Research Group, Durham University 23 November 2006 - Modelling rammed earth using soil mechanics principles

Structural Analysis of Historic Constructions 9 November 2006 - Analysis of Historic Rammed earth

School of Engineering Research Day 26 June 2006 - Analysis of Historic Rammed Earth

Archaeology Department, University of Durham 02 May 2006 - Historic Rammed Earth structures in Spain

ICE North Papers competition 05 April 2006 - Rammed earth structures

IStructE Young Researchers Conference 15 March 2006 - Analysis of Historic Rammed Earth

House of Commons Presentations by Top UK Younger Scientists and Engineers 13 March 2006 - Analysis of Historic Rammed Earth

Structural Analysis of Historic Construction 2004 11 November 2004 - Analysis of Rammed Earth structures for modern use and conservation

Copyright of the papers rests with a variety of different parties. They are made available solely on the same basis that I would supply a single copy of a paper to an individual. It is up to you to ensure that your use of a paper does not infringe copyright law.