![\"P1\"](\"https:\/\/www.tekuto.com\/wp-content\/uploads\/2015\/11\/P1-670x465.jpg\")
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<\/h2>\nMany of the buildings, by which we are surrounded, are mostly made of concrete. In fact, the history of concrete as a building material goes back a long time. It is known that the prototype of modern concrete was used for the construction of the Pantheon during the period of the Roman Empire. \u00a0 \u00a0 This highly durable material was called roman concrete and its main ingredient was volcanic ashes.<\/p>\n
Contemporary concrete consists of cement, sand, gravel and water. Although it has an artificial appearance, concrete is made from natural resources which are quite limited. It is up to us, living as we do in the 21st century, to have the wisdom of using limited resources more efficiently.<\/p>\n
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In the 20th century, the production of concrete which was the driving force for the building industry, made a constant increase in synchronicity with economic growth.<\/p>\n It is expected that the production of cement, being the main ingredient of concrete, will continue to increase. It is assumed that the consumption will be doubled by 2050 compared to the turn of the century. Additionally, cement is produced by heating natural limestone with other materials through a process known as calcination. In order to calcine at the high temperature of 1450 \u00b0C, a lot of heat energy is required that results in vast CO2 emission.<\/p>\n <\/p>\n <\/p>\n <\/p>\n The aggregate for concrete are gravel and sand. Both are natural resources.\u00a0Up until the economic boom, these materials were extracted from dry river beds or mountains resulting in drainage of good resources. Instead manufactures started to use sand from the seas. This results not only in the rusting of the reinforcement bars in concrete, but also contains many chlorides that originate from the sea water, which causes a general deterioration of quality of the concrete. Moreover, the extraction of beach sand is being regulated or banned by many local governments, because of the bad effects it has on the marine environment.<\/p>\n It is a matter of utmost urgency with in the concrete industry, clearly an industry that is indispensable to contemporary architecture, to search for alternative resource that could be utilized instead of sand and gravel. Also to change the formation of the recycling process of concrete, develop a more durable and multifunctional concrete.<\/p>\n This is how we came up with the idea for the practical use of volcanic “SHIRASU”\u00a0as a fine aggregate.<\/p>\n <\/p>\n “SHIRASU” is a general term for the deposit of pyroclastic flow of volcanic ash found in South of Kyushu. It covers almost half of the Kagoshima prefecture (4,600 km2<\/sup>) with an average thickness of 60m.<\/p>\n The amount of deposits are estimated to be 75 billion\u00a0m3<\/sup>, enough to fill the Tokyo Dome 60 000 times. Since it is not suitable for agriculture due too high drainage and scarce nutritive substances, and corrosion and mudslides easily happen at the time of heavy rain, it is regarded as an unwelcome troublesome material.<\/p>\n <\/p>\n Although “SHIRASU” had little or no value, our predecessors have not necessarily been sitting back with their arms folded.<\/p>\n Various researches on possibilities of utilization of “SHIRASU” have been carried out. It was used as a pavement subgrade material in the engineering field and also as land reclamation material. There has also been research in developing plaster material from “SHIRASU” but because of its qualities such as porosity, it was not authorized to be used as building material by the Architectural Building Codes.<\/p>\n The idea of utilization of regional untapped materials such as “SHIRASU” in a concrete industry brought our team together to be established in 2012.<\/p>\n Our motive is to support the utilization of “Shirasu” resources, which is located in the Kagoshima prefecture and in parts of the neighboring prefectures, to develop fully recycled, environmentally friendly concrete from “SHIRASU” and bring this new material to the building industry.<\/p>\n Members : Yasuhiro Yamashita (Visiting Professor at Kyushu University and founder of Atelier Tekuto), Takafumi Noguchi (Professor at University of Tokyo, Researcher in fully recyclable concrete), Jun Sato (Associate Professor at University of Tokyo,\u00a0 Structural Engineer), Kazuro Higashi (Incorporated Company Principle Representative Director, “SHIRASU” Producer), Tsukasa Ito (Managing Director Tokyo SOC, “SHIRASU”\u00a0concrete manufacturer).<\/p>\n With the cooperation of researchers at Kagoshima University, Kagoshima prefectural research institution, “SHIRASU” manufacturers, structural engineers and the concrete factory the project thus begun.<\/p>\n <\/p>\n <\/p>\n Four obstacles to construction: Material development and management.<\/strong><\/p>\n Through the investigation of the project team for using “SHIRASU” in architecture became very clear. To tackle these obstacles each of the members performed their part in a highly professional manner to seek out the appropriate solutions.<\/p>\n Obstacle 1. To meet the Architectural Building Codes.<\/strong><\/p>\n The highest constrain in using “SHIRASU” in the fields of Architecture was conformity to the Architectural Building Codes.<\/p>\n The pyroclastic ashes originate in the volcanos and is a totally natural material and because of the fineness of its grains which is lighter than the sand as represented in the JIS standard, and having too much moisture prohibits its use in architecture.<\/p>\n Various experiments were conducted with “SHIRASU” added concrete on its strength. As a result, we found if we limit the use of “SHIRASU” to one building per special Individual Ministry of Construction Approval. Then we would win approval for the use of “SHIRASU” in architecture.<\/p>\n Obstacle 2. Quality control of “Shirasu”<\/strong><\/p>\n Acquisition of an Individual Ministry of Construction Approval for “SHIRASU” concrete can be guaranteed only by the thoroughness in the quality control of \u00a0“SHIRASU” , to the extent where the natural hence variable qualities of “SHIRASU” was controlled to a high level where it could be called an industrial material. Therefore, \u201cPrinciple\u201d, the “SHIRASU” manufacturing company devised a quality controlling method and compiled a manufacturing manual.<\/p>\n <\/p>\n <\/p>\n Obstacle 3. Plant that can produce the concrete.<\/strong><\/p>\n Our aim was not only to document our research about using “SHIRASU” concrete but to actually use this material in a building. Even if the development of this material is possible, if there is no factory that will manufacture it, it cannot be used on the actual construction site.<\/p>\n So we had to search for a factory that could allocate a manufacturing line exclusively to “SHIRASU”. This was made possible by the participation of Tokyo SOC, having ample storage facilities and multiple manufacturing lines.<\/p>\n Obstacle 4. Checking the workability of the material on site.<\/strong><\/p>\n An architectural building is much smaller compared to civil engineering structures in which “SHIRASU” concrete had been used in the past. Good results and data obtained in the lab or the factory under optimized conditions does not necessarily mean construction will be smooth on the site, where the factor of uncertainty is an unavoidable risk. In order to extract in advance the element that is likely to pose a problem and to prepare solutions, a full-scale construction experiment was conducted. Construction of a full-scale mock up as a casting experiment resulted in the confirmation of a beautiful smooth finish.<\/p>\n <\/p>\n The task of bringing “SHIRASU” to the manufacturing process and to start using it as a building material was not an easy one. We needed to undergo verification of all aspects of “SHIRASU” concrete. Form different physical properties of \u00a0“SHIRASU” , such as neutralization examination, test of durability and examination of the different mixtures of proportions of ingredients in order to find the optimum solution.<\/p>\n Along with laboratory tests of material samples we constructed full-scale mock up in order to have real size concrete pouring experiment, durability check and to study material performance throughout the four seasons of the year. From the project team launch in 2012 through nearly two years of development experiments, finally in March 2014, we were able to acquire the “individual ministerial approval\u00bb to build one house using “SHIRASU” \u00a0concrete.<\/p>\n <\/p>\n 1. Contribution to the preservation of natural resources.<\/p>\n \u30fb60% to 70% of sand in concrete, which is becoming a scarce resource, can be replaced by “SHIRASU”.<\/p>\n 2.\u00a0Environmentally friendly.<\/p>\n \u30fbThe concrete becomes completely recyclable as a cement raw material at the time of demolition. 3. Strength and durability<\/p>\n \u30fbStrength and durability that increases to grow over a long period of time because of the pozzolanic reaction of “SHIRASU”, resistant to sulfuric acid and salt-damage 4. Smooth surface, humidity controlling qualities<\/p>\n \u30fbSmooth texture allows to have exposed concrete as fine finish. <\/p>\n On the occasion of “SHIRASU” concrete development, a client appeared before us. The client wanted a house on a compact site located in the center of Tokyo. Their requests were as follows:<\/p>\n \u201cWe want to see exposed concrete finish inside and out. We want a distinctive piece of architecture that is at the same time environmentally conscious.\u201d Environmentally friendly “SHIRASU” concrete was perfectly matching the special request of the clients regarding material and construction.<\/p>\n With those ideas as a starting point, Atelier Tekuto conducted various studies and researches with collaborators for the first “SHIRASU” concrete house which named is “R, a torso, and C” to be built in 2015.<\/p>\n![](\"https:\/\/www.tekuto.com\/wp-content\/uploads\/2016\/06\/P2_ENG.jpg\")
<\/a><\/p>\nCurrent Status of Concrete – 1<\/h2>\n
<\/p>\nCurrent Status of Concrete – 2<\/h2>\n
<\/p>\nWhat is \u201cSHIRASU\u201d?<\/h2>\n
<\/a><\/p>\nHistory of “SHIRASU” studies<\/h2>\n
<\/p>\nProject Members<\/h2>\n
Obstacles to the Use in Architecture<\/h2>\n<\/p>\nObstacles to the Use in Architecture<\/h2>\n
Acquisition of Minister Approval for the Individual Project<\/h2>\n<\/a><\/p>\nCharacteristics of Environmentally Conscious \u201cSHIRASU\u201d Concrete<\/h2>\n
\n\u30fbCalcination energy [of the cement] and CO2 emission can be reduced.<\/p>\n
\n\u30fbAlso its density, which comes from the fine granularity of “SHIRASU”, protects the concrete from neutralization<\/p>\n
\n\u30fb”Shirasu” also contains micro closed-cells which give the concrete humidity control and deodorizing qualities.<\/p>\n<\/h2>\n
<\/h2>\nFirst Architecture Using “SHIRASU” Concrete<\/h2>\n