HOW MUD BRICKS WORK: A YEAR OF RESEARCH
Transcription
HOW MUD BRICKS WORK: A YEAR OF RESEARCH
HOW MUD BRICKS WORK: USING UNSATURATED SOIL MECHANICS TO EXPLAIN THE MATERIAL PROPERTIES OF EARTH BUILDINGS A YEAR OF RESEARCH DR PAUL JAQUIN EDINBURGH, RAMBOLL UK Introduction • Paul Jaquin, MEng and PhD at Durham, now a Civil engineer for Ramboll in Edinburgh • • • • • This presentation - a year of research Last year’s paper Mud bricks and unsaturated soil The state of research into earth building Comparisons to other more conventional building materials Structural and mechanics research Low carbon and building physics Heritage structures The way forward…... • • • • Unsaturated soil and mud bricks • • Based on my PhD work, where we showed that mud bricks are basically like sandcastles, held together by little bridges of water. Potentially a step change in understanding of mud bricks, enabling a more scientific understanding. 5μm spheres with water bridges between Sandcastles Weston-super-mare beach Mud brick home. Pokara ,Nepal Existing research in earth building • • • • Materials specification method based and improvement based on experience Structural design based on empirical methods and very simple testing Most NGOs work to simple guidelines which are not developed from year to year. Only New Zealand has developed full design guidelines Scale model earthquake tests. Minke (2001) Steel,concrete, timber and masonry • • • • 1781 - Ironbridge. 1824 - Portland Cement developed 1884 - Reinforcement using twisted steel. 1917 - ASTM develop standard formula for Portland Cement. • • 1992 – 2010 - Eurocodes developed International Building Code - United States • • Little mention of earth building Little scientific understanding, therefore difficult to develop codes of practice. Research this year – Materials testing and structural mechanics • • • Durham University – Chris Beckett Bristol University – on next! University of Western Australia – Cyclone loading Poured particle arrangement Shaking table Wind loading test apparatus Research this year – Low carbon and building physics RHexternal = varies • • • Visiting research fellow at Bath University Continued by Antonio Borges Thermal modelling by Celia Macaedo. Oxford Brookes RHexternal = 100% RHexternal = 50% Water vapour flow Water vapour flow RH internal = varies RH internal = 50% RH internal = 75% Building construction 100% RH outside, raining. Water vapour flow through the wall, increasing internal RH RH = 50% 1 RH= 50% RHexternal = varies RH internal = 75% Introduce water vapour source (eg cooking), water Over time RH of the inside vapour flow through wall, of the building becomes reducing internal RH constant RH = 70% 2 RH = 50% Water vapour flow RH = 70% 3 RH = 60% 4 RH = 60% RH = 50% Water vapour flow Water vapour flow RHAir=change 50% Initial conditions, RH of room and pore air are equal at 50% Introduce water vapour source, increase in water content of the earth wall, RH of room remains constant as water vapour is absorbed into the wall Remove water vapour source, RH of room increases Air change, different RH from outside Research this year – Heritage structures • • University of Seville - Jacinto Canivell Pan- European – New Integrated Knowledge Based Approaches to the protection of cultural heritage from Earthquake induced Risk (NIKER) The way forward • • Recent posters by UN Habitat Long way from Eurocodes • New Zealand has developed Standards. These should be used by NGOs when building with earth • Research such as that presented here to be integrated into design codes and allow engineers for NGOs to design these buildings correctly. • Eurocode for earth buildings please Earth building THANK YOU [email protected]