Thesis Abstract

<p>                <b>ABSTRACT</b><br></p><p>The search for alternative building materials has continued in the research world. Some of these researches are for low cost housing; others are for environmental friendly materials, while others are for strength and durability. This has prompted research into even agricultural wastes. Considering the heaps of rice husk and sawdust wastes in the country, this study set out to investigate the possibility of their usage in building construction. The study set out to produce walling materials using rice husk and sawdust as aggregate. Ten specific objectives and ten research questions guided the study. The study used research and development research design. Eight hundred and sixteen specimens were produced and tested in the laboratory using California Bearing Ratio Compressive testing instrument. The bricks were of different mix ratios of binder to aggregate, cured using two different methods, namely the sun drying method and the room drying method. The mean was used as statistical tool for data analysis. The following findings were made The rice husk bricks attained their highest mean compressive strength of 0.05N/mm2 at the mix ratio of 31 (cement rice husk); The difference in strength attained by the rice husk bricks using either sun drying or room drying curing methods is minimal and can be ignored; The optimal dry strength of sawdust bricks is 0.05 N/mm2 while the wet optimal strength of sawdust bricks is 0.045 N/mm 2; The optimal strength of sawdust bricks is derived using the mix ratio of 31 (cement to sawdust); The room curing method produced the highest mean compressive strength in sawdust bricks; The mix ratios at which the highest compressive strength of composite bricks was attained were; 212 and 221 for dry compressive strength and 212 and 312 for wet strength. The mix ratio of 212 therefore is the mix ratio that gives the optimal strength; since it is common in both dry and wet testing; The highest compressive strength attained by the composite bricks was found to be 0.02 N/mm2 , when cured using both curing methods; Out of the three types of bricks tested, rice husk bricks have the highest mean compressive strength while composite bricks have the least mean compressive strength; Most tests carried out showed no significant differences in their results, either in the mixture ratios used, condition of testing (dry &amp; wet), or curing method. Based on the findings, some recommendations were made, which were The possibility of using rice husk in its natural form (un-burnt) should also be explored so that the heaps of wastes around the country will be reduced; Rice husk and sawdust are light materials, therefore they should be used with other materials like sand and clay to reduce the weight of walling materials and also provide both sound and thermal insulation to the house, especially in the tropical region; Since termites do not attack rice husks and sawdust when heaped on milling sites, they should therefore be used to reduce cases of termite attack on buildings; Efforts should be made by government and individuals to utilize Rice husk and sawdust, to generate power or a complement to cement just as other countries have done; Evacuation of waste products in our country is a problem. Heaps of rice husk and sawdust are seen at various milling sites. Government should therefore build industries to convert this waste to useful items thereby converting waste to wealth; rice husk and sawdust bricks can be used for partition walls that do not carry load. They may be expensive in production but they can minimise heat and sound transmission problems in the house, making the house energy efficient. <br></p>

Thesis Overview

<p> <b>1.0 INTRODUCTION&nbsp;</b></p><p><b>1.1 BACKGROUND OF STUDY</b></p><p>Humans have three basic needs, and these are food shelter and clothing. All efforts for technological advancement are hinged on the desire to effectively satisfy these basic needs. Among these basic needs, shelter, which includes housing, is the most difficult and expensive to provide. In this study shelter refers to housing. According to Agarwal (1981), the difficulty in the provision of housing is as a result of high cost of building materials which has contributed to make ownership of houses more and more difficult for the poor, especially in developing countries. A house comprises of four main parts which are constructed in stages. These parts include: Foundation, floor, walls and roof. Out of these parts it is the walls and the roofs that protect the house from the elements of the weather and also give it definition in distinct appearance. Walls are vertical, slender components of a building, accommodating the doors and window openings. Walls are of two types- load bearing and non-load bearing walls.&nbsp;</p><p>According to Chudley &amp; Greeno, (2006), walls serve the following purposes on a building – (i) provision of privacy to the occupants (ii) protection against attacks (iii) support to upper floors and roof (iv) transmission of building weight to the foundation (v) prevention of excessive heat loss from within the building as well as heat gain from outside the building. (vi) provision of barrier for sound transmission, (vii) offering of resistance to fire (viii) reduction of expansion and contraction of the structure (ix) prevention of condensation, and (x) division of floor space as well as forming storey heights. To achieve these purposes, walls are made of different materials. These materials include mud (Obande, 1981); gypsum boards (Reiner, 1981; Villa 1986) clay bricks, sandcrete bricks, concrete blocks (Ezeji, 1984; Seeley 1995). The use of these materials is determined by various factors such as cost effectiveness, and availability, durability, and ease of workmanship. Humans have continued to search for better cheaper housing. This has led to series of experiments and trial and errors on different and alternative materials. The search for durable and more affordable materials has led to exploration in the use of materials like wood, which according to Durbahn &amp; Sundberg (1977); Warland (1979), is used for both wall and roof construction. However, the walling materials that are commonly used in Nigeria include burnt clay bricks and sandcrete bricks or blocks (Ezeji, 1984). Bricks, according to Mckay (1979), are small building units that are arranged in a particular bond pattern to form walls. They are chiefly made from clay and shale. Their sizes range from a length of 210mm to 230mm, a width of 100mm to 115mm and a thickness of 38mm to 75mm. Conversely, blocks are the larger units, which are made mostly from sand and cement (Sandcrete) or sand, gravel and cement (concrete).&nbsp;</p><p>According to the Nigerian Industrial Standard (NIS,2004) and the Nigerian National Buidling Code (NBC,2007), the sizes of blocks range from a length of 450mm, a height of 225mm and a width of 100mm to 225mm. The constituent materials of the blocks are sand and cement for sandcrete blocks, and sand, cement and gravel for concrete blocks. Sand and gravel are referred to as fine and coarse aggregates respectively while the cement is the binder or matrix. Cement which is generally referred to as Portland cement because of its resemblance to Portland limestone, is derived from a mixture of lime, iron, silica and alumina (Allen, 2008). The use of walling materials is dependent on their physical properties like compressive strength (wet and dry), tensile strength, durability, rate and percentage of water absorption, density (bulk and dry), bonding strength, acoustic and thermal properties, as well as the modules of elasticity. These properties vary from material to material. To get the desired properties to satisfy a particular purpose for the wall therefore, some materials are combined into composites to complement each other so as to improve performance in service. Clay bricks used to be the most popular walling units because, according to Warland (1979), their firing in kilns gave them improved structural properties like compressive strength, durability and fire resistance. The firing also increased their aesthetic value as various colours, texture, and finish are developed, depending on the chemical composition of clay and shale. The texture, colour and finish also depended on the amount of alumina, magnesium, iron or calcium oxide available in clay or shale. According to Emitt &amp; Gorse (2005), the discovery of cement in 1824 brought a new revolution into the building industry. Cement which is a binder can be used to produce concrete and sandcrete bricks and blocks. Sandcrete bricks and blocks are not subjected to firing in kilns or furnaces, but are found to be structurally suitable for walling. Though the advent of cement has revolutionized building construction activities, the cost of building materials is still on the increase even in the present day. Badejo, (2002) observed that there was unprecedented increase in the prices of building materials in the country. It is observed that there has been a continuous hike in the prices of building materials. A bag of cement which cost between N800.00- N1,200.00 in 2007 cost between N1,600.00-N1,700.00 in 2008. It is also seen that a 4 bag of cement costs N1,800.00 in 2009,while it went to N2000.00 in 2011, but came down to N1600.00 in 2013, due to government intervention. In their view, Agbedi &amp; Joel (2008) stated that the cost of building materials, especially walling materials makes it imperative for further search into alternative cheaper materials, than clay bricks and sandcrete blocks to be sought. They observed that lateritic soil bricks had a cost savings of 47% when compared with sandcrete blocks of size 450x230x230mm. Similarly, fired clay bricks were also found to be cheaper than sandcrete blocks with a cost savings of 19%. However, production of fired clay bricks was noted to be labour intensive and costly, just as the acquisition of sandcrete blocks was noted to be difficult for the poor because of its high cost. The cost of these materials led to the search for alternative but cheap walling materials. Toledo, Ghavami, England, &amp; Scrivener, (2003) and Nemkumar (2003), have reported good results in the use of vegetable fibres in cement and concrete. Balaguru &amp; Ramakrishnan (1988) observed that in order to combat the high cost of steel rods as reinforcement; fibres were being used for reinforcement of concrete. Similarly, Kuroshi (1992), also identified that the use of sisal fibres improves the quality of clay bricks. It therefore implies that fibres, and by extension, agro waste materials, are prospects for building materials. The high cost of building materials and the need to find alternative materials were some of the reasons that prompted the Federal Government of Nigeria to establish the Raw Material Research and Development Council (RMRDC) in July 1989 to guide and promote research into available local raw materials to be used in the industries. The world is now searching for the utilization of agricultural (agro) waste materials in building, and Nigeria which is an agrarian nation abounds with agricultural waste materials like rice husk and sawdust, just to mention a few. Rice 5 husk and sawdust are available in large quantities at milling centres in both rural and urban areas. Rice husk, according to Allen (2003), is a by-product of threshing padi and it is about 20% of mass of harvested padi. According to Webley (2001), however, rice husk is a thin but abrasive skin covering the edible rice kernel. Rice husk contains 75 – 90 % organic matter such as cellulose, lignin etc. and the rest mineral components such as silica, alkalis and trace elements (Kumar, Mohanta, Kumar &amp; Parkash, 2012). Rice husks are found in large heaps round the country and they create disposal problems. In order to minimize the disposal problems therefore, many rice millers burn the husk, though some attempts are being made to put the rice husks to better economic uses. Rice husks are been used in Thailand as Bio-mass for generating energy (ASAPP, 2002). According to Rice Knowledge Bank ( 2013), rice husk has a thermal conductivity around 0.036 W/m 0C, which is comparable to most insulation materials. Rice husk has a potential to be used as a building material. Sawdust, another agro-waste material, is a by-product of wood, produced from sawing of wood. Longman Dictionary of Contemporary English (2007) describes sawdust as very small pieces of wood that are left when one has been cutting wood. Badejo and Giwa (1985), Akande (2001) have observed that large quantities of sawdust can be found in Nigeria around sawmills and wood based industries. Sawdust is largely seen as waste and so is not utilized. According to Ogunsanwo (2001), the non-utilization of the sawdust creates disposal problems, which are burdensome. Owonubi and Badejo (2000), therefore, observed that in order to dispose of the large sawdust hills around sawmills, that constitute visual blight to local environment, and also cause environmental pollution, saw millers resort to burning. The burning thus produces smoke and offensive gases like carbon 6 dioxide and carbon monoxide, which are hazardous to human health and contribute to ozone layer depletion. It is noted that throughout the world, developing countries face severe problems with regards to supply of building materials, which is the core of the construction sector, (Oruwari, Jev, &amp; Owei, in Nwankwor 2007). UNCHS, (2001) also noted that building materials consume 70% of the total cost of a building. This therefore makes it difficult to meet housing demands of the people. Howe (1992), therefore opined that meeting the shelter requirements in any nation will depend to a great extent, on the availability of building materials at affordable prices. Furthermore, the cost of housing must be kept within the limits of the ability of the owners to pay. Similarly, Kennedy (2002), also observed that availability and affordability in terms of cost of building materials, will greatly aid provision of housing.&nbsp;</p><p>However, the current scarcity and high cost of materials has not helped matters. To this end Howe (1992), and Kennedy (2002), have noted that domestic technology compatibility to produce quality indigenous building materials must be strengthened before success will be recorded in this regard. Oruwari et al. (2001), have noted however, that the success of housing development programmes (anywhere) hinges not solely on technical issues but include efficient management of existing resources and effective communication between communities and funders. The Federal Government’s National Economic Empowerment and Development Strategy (NEEDS, 2004) document has also advocated for production of environmentally friendly, low-cost, quality and affordable human shelter that are also very durable. This means development of cheaper sources of building materials, which must take into account sustainability and environmental friendliness of such products without compromising quality and standards of modern construction.&nbsp; According to Nwankwor (2007), there is growing global concern for the development of socially and environmentally friendly, quality building materials.&nbsp;</p><p>This study therefore aims at addressing this concern through this research into rice husk and sawdust as building materials.&nbsp;</p><p><b>1.2 STATEMENT OF THE PROBLEM</b></p><p>&nbsp;The cost of building materials, especially walling materials, in the country is very high. The production of burnt clay bricks is energy and labour intensive, and expensive. The use of firewood as source of energy to fire the bricks, leads also to depletion of the forests. It has also been observed that the high cost of cement has also made the cost of sandcrete and concrete blocks to be out of the reach of the poor. Furthermore, block industries, in order to maximize profit, reduce the mix ratio and that equally reduces the strength of the resulting blocks. However, the Federal Government is advocating for affordable (cost effective) housing for the people. Similarly, people have advocated for the use of alternative building materials using local building materials technology. If however, local materials are not available and the cost of building materials continues to rise, then the realization of the national policy on housing for all will not be possible based on the cost of building materials, especially walling materials. It should be stressed that affordable houses should also be of environmental and health friendly materials. The people of Nigeria for which the government seeks for ways of providing cost effective housing, are largely farmers.&nbsp;</p><p>Nigeria being mainly an agrarian country has a lot of agricultural produce and so there is large quantities of agro-based waste, like rice husk and sawdust, whose use could be of great help to the country. Rice husk and sawdust are produced at milling sites and heaped in the surrounding sites as 8 waste, for burning, because of the difficulty in their evacuation and non-utilization in any other meaningful way. Burning therefore, becomes the major method of its disposal. The burning of these wastes causes environmental pollution and hazards. Burning also causes soil degradation, brings smoke, causing health hazards. To prevent these hazards and improve our economy then meaningful use of these waste materials has to be found. ASSAPP (2002) opined that the conversion of industrial and agricultural wastes to building materials offers the twin benefit of shelter to the poor while also helping to retain the fragile ecological balance.&nbsp;</p><p>&nbsp;The problem of this study therefore is on the need to find ways of utilizing the rice husk and sawdust, which are presently waste materials, into useful products of walling materials (bricks). The study therefore produced walling materials using rice husk and sawdust as aggregates. The utilization of the rice husk and sawdust would solve the problem of waste disposal, environmental pollution and provide alternative walling materials which could improve both thermal and sound insulation to the building..&nbsp;</p><p><b>1.3 PURPOSE OF THE STUDY</b></p><p>The main purpose of the study is to produce walling materials (bricks) using rice husk and sawdust as aggregates. Specifically, the study is intended to determine&nbsp;</p><p>1. The mix ratio of binder to aggregate that will produce optimal compressive strength in rice husk bricks using different curing methods.&nbsp;</p><p>2. The optimal wet and dry compressive strength of rice husk bricks using different mix ratios and curing methods.&nbsp;</p><p>3. The curing method that will produce the optimal compressive strength in rice husk bricks using different mix ratios.&nbsp;</p><p>4. The mix ratio of binder to aggregate that will produce optimal compressive strength in sawdust bricks using different curing methods.&nbsp;</p><p>5. The optimal wet and dry compressive strength of sawdust bricks using different mix ratios and curing methods.&nbsp;</p><p>6. The curing methods that will produce the optimal compressive strength in sawdust bricks using different mix ratios.&nbsp;</p><p>7. The mix ratio of binder to aggregate that will produce optimal compressive strength in composite bricks using different curing methods.&nbsp;</p><p>8. The optimal wet and dry compressive strength of composite bricks of different mix ratios using different curing methods.&nbsp;</p><p>9. The curing method that will produce the optimal compressive strength in composite bricks using different mix ratios.&nbsp;</p><p>10. The type of brick (RH, SD, CP) that will produce the highest compressive strength.&nbsp;</p><p><b>1.3 SIGNIFICANCE OF THE STUDY&nbsp;</b></p><p>The findings of this study will be of benefit to individuals and groups, including building technology teachers and students, rice farmers, wood workers, the society and government. These groups of persons and organization will benefit in varying ways. Building technology students and teachers will benefit from the study by having access to suitable skills required to successfully manufacture rice husk and sawdust bricks, identified by the study. The technology in building construction will therefore be enhanced. Rice farmers will benefit from the cleaner environment created as a result of the husk evacuation for brick production, when people are made aware of the 10 benefits of rice husk bricks. Furthermore, the farmers would have boosted their economy through the charging of small fees for the evacuation of the product. Carpenters and wood workers would also benefit from the cleaner environment that will be created through the evacuation of the sawdust from their sites, for brick production. The sawdust now evacuated creates a cleaner environment as opposed to the visual blight it used to create. Additional funds could also be realized through the charging of small fees for the evacuation of the sawdust. The health hazards that accompanied the burning of the sawdust on site as a means of evacuation will also be minimized. <br></p>