Vernacular rammed earth structures common in China.
The following is a guest post by Dr. Rongrong Hu, professor at Xi'an University of Architecture + Technology and an expert on rammed earth in China. She visited Rammed Earth Works and gave a talk at the Hamel Winery called “Rammed Earth, A Historical Perspective And a Solution to Modern Day Challenges”. We enjoyed her visit, learned tremendously from her international experience, and are proud to share the report of her trip :
When I step on the thousand year old Great Wall of China built with rammed earth or when I see the old and beautiful vernacular rammed earth houses in China, a question about rammed earth construction always comes to my mind: what is the future of this disappearing ancient construction technique with such a long history in China?
To help me find the answers, David Easton, founder of Watershed Materials and Rammed Earth Works arranged a trip to Napa where his companies are headquartered. Arguably, Napa is California’s rammed earth country. Going to Napa, I really did not know what to expect. I knew David is very passionate about rammed earth construction, after all he has devoted most of his career to this technology and specifically to creating a new construction block made with technology that evolved from rammed earth. However, I did not know I was about to meet so many enthusiastic people from different walks of life, all with the common goal of furthering the progress of this technology.
Dr. Rongrong Hu and David Easton at the Watershed Materials headquarters, standing in front of a building made with rammed earth Watershed Block below rammed earth PISE.
I drove to Napa valley on Saturday, August 21st. Arriving early afternoon, first on the agenda was a tour of David’s extensive laboratory on rammed earth. As I walked around David’s lab, he explained to me how he has built this state of the art lab with the aid of National Science Foundation (NSF). I was encouraged to see that the United States’ government is supportive of the sustainable building technology. David had built a truly magnificent laboratory equipped with all sorts of machinery to measure everything that could potentially be measured on his new technological marvel, the Watershed Block. In the front portion of his lab, he was conducting tests on strength, drop testing, water absorption, contraction, expansion and many other tests which we did not have time to delve into.
His lab was well equipped beyond any other lab I had seen. He explained his vision of how he thought the Watershed Block could be built with little or no cement, yet capable of meeting the needs of our modern day construction practices. His Watershed Block resembled an ordinary concrete block, but the cement content is substantially reduced. I was amazed at the strength of David’s Watershed Block. The natural question was how was he able to get such amazing strength? Then David explained how he had to invent a kind of rammed earth pressing machine, capable of putting tremendous amount of force on these blocks and this force was key to creating the strength needed. As we walked together to the back of his lab, he showed me his machine connected to conveyor belts and motors powering it. This second generation machine was capable of producing 4 blocks every minute. Connected to the machine were long conveyor belts carrying the blocks away from the pressing machine. It was easy to get impressed by all the technology in David’s laboratory.
Rammed earth home in Northern California built by Easton's Rammed Earth Works
After visiting David’s lab, it was time to visit some of the houses built using David’s technology. David drove me to visit some modern rammed earth homes and their owners. They graciously welcomed us into their homes and shared their stories, opinions and passion of rammed earth with me. They told me the reasons they chose and love their rammed earth homes. Thanks to all the modern rammed earth home owners for their encouraging words. Their stories, their opinions, their love of rammed earth will contribute to the rammed earth construction development in China.
On the evening of August 22, 2015, an event was hosted by Mr. Hamel in the beautiful Hamel Family Winery to showcase rammed earth construction. I was the invited speaker. I was impressed by the amazingly beautiful new winery which was built with massive rammed earth walls perfectly becoming a part of natural landscape. It is an obvious masterpiece of modern architecture. I am not a wine expert, but I was told the wine was excellent. Wonderful hospitality, great wines, beautiful view from inside and outside, what an unforgettable experience! The Hamel family were such gracious hosts. They had paid attention to every detail. I will always remember their hospitality. Many thanks to the Hamel family!
Dr. Rongrong Hu at the Hamel Family Winery before her presentation on the history and future of rammed earth in China.
There were guests from every walk of life. Some were architects and engineers, some had their homes built with rammed earth, yet others were just intrigued with the technology and were considering construction projects. I had prepared a presentation on rammed earth history in China and how we have started to use this technology again to solve our modern day pollution problems.
My presentation was full of colorful pictures on China’s popular rammed earth monuments. It probably went longer than I expected. After the presentation, I expected most guests to dash out of auditorium given I went over my allotted time.
However to my surprise, many of the audience came to the podium after the presentation to ask about rammed earth construction today in China. They were all hopeful that rammed earth becomes mainstream in Chinese construction, especially in rural China. The guests also shared their stories and opinions on rammed earth construction. They all believed rammed earth construction has a bright future because of its history, light carbon footprint, beauty, and comfort.
After the event I wanted to do a more thorough survey. I was wondering how the guests really felt about rammed earth. The responses were overwhelmingly positive on rammed earth. I took the liberty of compiling some of the guest responses at the end of this note.
I had a great time in the beautiful Napa Valley. And I owe gratitude to many. Specially, I like to thank David any Cindy Easton for inviting me to Napa and hosting me at their beautiful home. Their inviting hospitality made me feel right at home. I also like to thank the Hamel family again for the wonderful event they hosted. I am grateful for all their hospitality.
Last but not least, I like to thank all the guests came to the event who shared their valuable opinions with me and thank the home owners who welcomed me to their homes. Their valuable opinions will guide me and others in the Chinese academia in shaping the future of rammed earth construction.
“I truly believe rammed earth construction has a future, especially as we try to change our construction methods/techniques to protect the planet and ensure a healthier environment for future generations.”
“I think that’s the key to the future of rammed earth - it’s past. History has proven it’s beauty, functionality, and resiliency.”
Dr. Rongrong Hu speaking about the history and future of rammed earth in China to a group of rammed earth advocates knowledgeable about rammed earth in the United States.
“Rammed earth is usually reserved for those US projects with a healthy budget. It will be interesting to see if the Chinese can do it affordably and safely. I am even more excited about the future of your rammed earth CMU as it is a valuable tool for Architects. Since the price is similar to concrete CMU, the real advantage is that you achieve an extremely attractive interior and exterior finish, that’s the REAL savings.”
Dr. Rongrong Hu speaking with attendees of her presentation asking them their feelings on the future of rammed earth.
“The answer is ‘absolutely yes, rammed earth has a big future.’ In a century where population growth and rising standard of living demands more and better housing - at the same time as our most precious resources of clean air and pure water are diminished - it is imperative and inevitable that we find ways to build that have a lighter carbon footprint, and less impact in general on resources. The efficiency of rammed earth, from the perspective of its very small carbon output, its ease of manufacture, and assembly, and its reduction in operating costs for the resident, all make it a certain winner in the race for better building techniques. In the words of a great Hollywood film, Back to the Future!!”
“Do I think rammed earth has a future? Absolutely, having enjoyed lived in a rammed earth home for 15 years it is hard for me to imagine not living with the beauty, sustainability, convenience and comfort of living in this earth home.
What I enjoy most about rammed earth is the beauty and solid structure. I also feel a sense of stability and strength from the home, having experienced a 6.0 earthquake close to the epicenter without an item out of place. Education for architects, building contractors, and building departments to familiarize with the design and engineering techniques and developing a cost structure to compete with traditional building methods will hopefully change this in the future.
The work that David Easton and his colleagues in the industry are spearheading, including the availability of techniques like the rammed earth blocks, may be key to the future of rammed earth. I certainly hope that this method will bring the wonderful lifestyle of this building to many around the world.”