Utilization of vetiver grass in construction materials | |
| Author | Thammanoon Hengsadeekul |
| Call Number | AIT Diss. no.ST-06-01 |
| Subject(s) | Vetiver Construction industry--Materials management |
| Note | A dissertation submitted in fulfillment of the requirements for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ST-06-01 |
| Abstract | The purpose of this study is to investigate the performance of vetiver grass-clay composite for the construction of a paddy storage silo and utilization in the form of prefabricated blocks for housing applications with the possibility of using vetiver grass ash as pozzolan. The experimental program is divided into two parts. The first part deals with the utilization of vetiver grass as construction material for paddy storage silo. Jaturapitakkul (1987) investigated the mechanical properties of strawclay composite and used that material to construct a low-cost silo for paddy storage. The test results showed that straw-clay composite was good insulating material and the thermal conductivity of that material was lower than that of concrete by approximately twenty times. At present, a harvester and thresher tend to be used, as well as the rice straw obtained is short and not suitable for use. Therefore, vetiver grass has been adapted to substitute rice straw, and been used to reinforce clay slurry or adobe. Basically, vetiver grass serves as reinforced fiber and clay as matrix. However, before determining the physical and mechanical properties of the vetiver grass-clay composite, the properties of vetiver grass and clay are separately determined. A study of the characteristics of vetiver grass and its usages was conducted. Testing of vetiver grass in terms of moisture content, water absorption and direct tensile strength was carried out. Clay was also tested in terms of specific gravity, moisture content, liquid limit, plastic limit, shrinkage limit and particle size analysis by hydrometer. A fabrication technique of the vetiver grass-clay bundles was also conducted. The vetiver grass-clay bundles were tested for the percentage of weight loss, density, axial compression strength, flexural strength, shearing strength, tensile strength and bearing strength. Following these tests, a cylindrical vetiver grass-clay composite silo at the Royal Chitralada Project was constructed as a prototype. Paddy was stored in order to evaluate the silo's performance by investigating the quality of the stored paddy in terms of moisture content, bulk density and milling yield for a period of six months; and parallel, by measuring the temperature and relative humidity at different locations in the silo to record the changes in each period. Moreover, a study for suitable coating material for the silo wall was also conducted. The results indicated that vetiver grass-clay composite plays a vital role in being a good insulating material that can reduce any effects from temperature and relative humidity outside the silo. From the research of mechanical properties of vetiver grass-clay bundle, it can be concluded that the composite was structurally strong; the vetiver grassclay composite silo has proven that it represents good storage performance for a period of six months or even longer. The study showed that this composite silo demanded sun-drying; therefore, construction should be undertaken in the dry season with strong sunshine to reduce the moisture content as quickly as possible. From the study, it was found that fungi fertilization could appear if the drying vetiver grass-clay composite was not completed or the moisture content was not less than twenty percent within three normal days. This occurrence could be solved by adding a fungi prevention compound (TERRACLOR SUPER XE). Thus, the study and performance evaluation of the prototype silo proved that vetiver grass-clay composite has effective physical characteristics to construct a paddy storage silo. However, there are some construction limitations, such as, the requirement of dry weather, longer construction time and construction needs at the site. As such, further development of vetiver grass-clay composite to a prefabricated block for more applications and practicality was conducted. The study included geometric block design for practical use, design and creation of simple press equipment by using human force, and production techniques. To minimize the production time, an accelerated drying technique was studied. The physical and mechanical properties including percentage of weight loss, density, bearing strength, flexural strength and load-bearing wall tests were conducted. The construction of a mock up room was demonstrated to present the construction process and monitoring. A cost and performance analysis between the traditional masonry wall and the proposed prefabricated block wall were conducted. Moreover, four types of coating materials and two types of surface preparation were carried out to find the appropriate coating material. The study showed that the prefabricated vetiver grass-clay composite blocks which could be used as a load-bearing wall for a house or storage silo have considerable potential to construct low-cost housing. The blocks are similar to burnt clay bricks but larger in size, and lighter in weight. They are strong and hold together firmly because of the block's design that has a shear key and interlock in the horizontal and vertical joints. The blocks are also energy-saving because they do not need burning but can be sun-dried. They are easily workable, noise resistant, non-toxic and can be assembled to form walls within a short period of time. The second part of this study deals with the feasibility of using vetiver grass ash as pozzolan. The development of a new kind of building material and cementitious material based on vetiver grass ash for use in the rural areas of developing countries is being experimentally investigated. The properties of vetiver grass ash were experimentally studied for the possibility of using vetiver grass ash as pozzolan. An experimental program was conducted to determine the physical and mechanical properties of vetiver grass ash, cement mortar and lime mortar containing vetiver grass ash. The vetiver grass ash fineness, chemical composition, and setting time were investigated. The properties of cement mortar and lime mortar containing vetiver grass ash including compressive strength and amount of water requirement were also investigated. The test results were compared with those of the ordinary Portland cement mixes. Moreover, possible applications of vetiver grass ash mortar were indicated. The study revealed that vetiver grass ash, according to the ASTM C 618 requirement, can be classified as class C pozzolan. Vetiver grass ash can be used as a replacement for cement or combined with lime. With the partial replacement of vetiver grass ash, it enables the cement paste to have more density, less void, less alkaline and be more durable. The process is also simple, economical and well suited for rural areas in developing countries. The study also recommends that vetiver grass ash can be suitably adopted as a construction material for foundations, marine structures, sewers, and other chemically exposed structures. The research reveals that apart from the benefit of land rehabilitation and water conservation, vetiver grass can be used as fiber reinforcement in clay matrix to make composite suitable for the construction of a silo, to develop into prefabricated blocks for the construction of a low cost housing, and to burn and grind for use as a replacement for cement. In addition, vetiver grass and clay are abundant indigenous materials in developing countries and the construction using a vetiver grass-clay composite is inexpensive and requires local labor skills. Therefore, this would help developing countries, which are now facing problems at a commercial level to overcome underdeveloped problems and bring about a better economy and living standards |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ST-06-01 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pichai Nimityongskul; |
| Examination Committee(s) | Tawatchai Tingsanchali;Bergado, Dennes T.;Naaman, Antoine E.; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institutte of Technology, 2006 |