High Rice Buildings

I like a bit of Science.

None of that theoretical nonsense but just a scientific explanation for the ordinary and mundane things in our lives.

Take amylopectin, for example.

It is a type of polysaccharide or complex carbohydrate.

It is an interesting compound in that it inhibits the growth of calcium carbonate crystals when added to building mortar with the consequence of producing a compact microstructure that ages well.

Scientists have discovered that it is this characteristic that explains why many historic Chinese temples, pagodas, tombs and walls, including the Great Wall itself, remain as strong and resolute to the forces of nature and the destructive progress of Man as they did when brand new.

Archaeological evidence shows that amylopectin, as an ingredient was in use some 1600 years ago. The super strong material, scientific explanations aside, is the sweet glutinous dessert served in many Thai Restaurants with coconut, milk and mango and used in many Asian cuisines and popularly known as Sticky Rice.

When added to slaked lime it produces the composite organic/inorganic mortar of legendary strength and durability.

Ancient Chinese Builders may have arrived at the use of Sticky Rice through experimenting with other everyday additives to mortar including tung oil, fish oil, animal blood and egg whites. Their Mediterranean counterparts were known to use eggs, pigs milk and straw or whatever happened to be lying around.

An alternative theory is that it may have been a purely accidental discovery over a labourer's  lunch spilt into the mortar mix and then hastily covered up by being built into masonry to avoid recriminations from a gang master.

The Laboratory of Cultural Relic Conservation Materials at Zhejang University in Hangzhou has called the material one of the greatest technological innovations of the time.

 Some of the structures benefitting from the everyday ingredient have survived not only the millennia but also multiple and powerful earthquakes in some provincial regions. This was the case with some religious buildings and bridges which survived a magnitude 7.5 tremor in 1604. The earliest record of sticky rice mortar is found in a construction manual from the Ming Dynasty from 1368 to 1644. Excavations of considerably older sites show that the technique was already in widespread use by the South-North Dynasty from 368 to 589.

The Hangzhou Laboratory conducted experiments to compare plain lime mortar with the sticky rice version and found the latter to have superior mechanical strength. The value of the material and its relative low cost is that it can still be used today in the numerous restoration projects involving ancient stonework structures.

One tomb, built during the Ming Dynasty was so resolute with the sticky rice binding that a mechanical bulldozer was thwarted in an attempt to make any impact. Another quality of the material is that it is less permeable to water and more resistant to the stresses of climatic change than standard mortar. This makes it very compatible with the bricks used in old buildings and the best option for conservation and restoration.

In contrast the use of modern mortar has often exerted too much pressure on old bricks causing them to crack and fail.

The most magnificent of man made structures, The Great Wall of China, is largely indebted to the sticky rice mortar for its longevity along the 3889 miles of its brick and stone walls which make up the recognised length of 5500 miles and what is actually thought to be in excess of 13000 miles when all constituent parts including trenches, earthworks and offshoot walls are included.