جستجو در تالارهای گفتگو

PERFORMANCE OF NON-FIRED GREEN BRICK CONTAINING RICE HUSK AS SUSTAINABLE BUILDING MATERIAL ( Received: January 04, 2016 – Accepted: February 06, 2016 ) Abstract The demand for sustainable alternative construction materials to cement in modern technology cannot be underemphasized. This paper presents a non-fired green brick with an agriculture residue namely, rice husk. Although, high plasticity brown clay deposits are widely distributed in Malaysia and rice husk is a well known agriculture residue, research works on non-fired green brick with rice husk are relatively scarce. This research aims to investigate the strength development in non-fired bricks containing various amounts of rice husk. To achieve such aim, compression and flexural tests were conducted to evaluate compressive and flexural strengths of non-fired bricks. A series of brick specimens were cast with varying rice husk percentages. The test specimens were naturally sun dried. The effects of rice husk percentage (9-15%) and drying age (1, 7, 14, 21, and 28 days) on Atterberg limits; compressive strength; water absorption and flexural strength were investigated. The results indicate that, 12% rice husk is the optimum content to reach maximum 28-day compressive and flexural strengths of 10.4 MPa and 3.5 MPa respectively. The results further showed that rice husk higher than 12% leads lower strength than control bricks for all the ages. In summary, it has been observed that rice husk enables a rapid strength development, enhancing the compressive and flexural strengths of the bricks. The results developed in this research work can contribute a cost-effective design of non-fired green brick as a sustainable building material. Keywords Non-fired brick, Rice husk, Strength, Sustainable material چکیده نیاز مبرم به مصالح و مواد جایگزین سیمان در صنایع پیشرفته غیر قابل انکار است. در این پژوهش یک نوع آجر بدون نیاز به فرایند پخت در کوره به همراه پوسته برنج به عنوان پسماند صنایع برنج کوبی معرفی گردیده است. گرچه خاک رس به عنوان ماده اصلی آجر ساختمانی به وفور قابل دسترسی بوده و پوسته برنج نیز پسماندی شناخته شده است، ولی تحقیقات صورت گرفته در خصوص آجر های غیر کوره ای اصلاح شده با پوسته برنج بسیار محدود می باشد. در تحقیق حاضر تاثیر درصدهای مختلف پوسته برنج بر مقاومت فشاری و خمشی آجرهای عمل آوری شده در هوای آزاد مورد بررسی قرار گرفته است. نتایج آزمایشات آزمایشگاهی نشان می دهند که مقدار 12 درصد پوسته برنج بیشترین مقاومت فشاری و خمشی را بعد از 28 روز روند عمل آوری آجرها نتیجه می دهد. بنابراین مقدار بهینه پوسته برنج برابر 12% می باشد. دانلود منبع 29-3-4.pdf

Effect of Polypropylene Fibers on Strength and Thermal Resistance of Concrete Jamal Ahmadi; Hossein Aghajanloo In this paper, the effect of Polypropylene Fibers added to concrete on strength and thermal resistance of high strength concrete has been investigated. Therefore, five tests have been carried out to reach this goal which it includes; effect of weight percent of polypropylene fibers on mechanical properties of concrete, effect of fiber’s length on the strength of high strength concrete, effect of fiber’s volume on the thermal stability of high strength concrete, examine the phenomenon of spalling concrete high resistance against heating, determine the changing of compressive strength of high strength concrete in different temperatures. The results present that the compressive strength has declined with the percentage of fiber concrete after 0.7 kg/m3 . Moreover, in all cases the tensile strength and concrete’s bending strength will be increased by fiber content. منبع دانلود JSEG471443558600.pdf

Long Term Dry and Wet Effects on the Engineering Behavior of Subgrade Soil with High Amount of Soluble Salts using Low Cost Stabilizers Original Article, D74 Ibrahim S.F., Ibrahim M.S., Abd hak H. J. Civil Eng. Urban. 4(5): 492-500. 2014 ABSTRACT: The performance of pavements depends upon the quality of subgrades. A stable subgrade and properly draining pavement help to produce a long-lasting pavement. Subgrade soil provides support to the remainder of the pavement system. This study is performed to evaluate the effect of total soluble salts (T.S.S.) on the strength of subgrade soil brought from Al-Mahmodia city south of Baghdad. Chemical and physical test, carried out on the soil sample, indicate that, the soil is lean clay of (CL) group according to the Unified Soil Classification System (U.S.C.S.). The soil sample contains about (15.685%) by weight of (T.S.S.) content. Different stabilizers are added to the subgrade soil to study the influence of these stabilizers on (T.S.S.) and the strength of subgrade, the stabilizers are (5% lime, 2.5% calcium chloride, 6% kaolin, 6% Rice Husk Ash and 5% saw dust). California Bearing Ratio (CBR) test is determined for the natural soil and different stabilizers with different number of blow per layer (10, 25 and 56) for (4-days) soaking periods under (10 Ibs.) surcharge load. The number of blow per layer and (CBR) value, required to achieve (95%) relative modified proctor compaction are determined from the results of different number of blow (10, 25 and 56) and soaked for (4-days). The (CBR) value of the natural soil at 95% relative modified proctor increases by about (48%, 66.1%, 36.1% and 38%) for the (2.5% CaCl2, 5% lime, 6% RHA, 6% kaolin) respectively. While the CBR value of soil with the (5% saw dust) decreases to (29%). The (T.S.S) is reduced after the addition of the different stabilizers. Durability test (long term soaking) for the subgrade stabilized with (6% RHA) and compacted at 95% relative modified proctor is conducted, the results of soaking showed reduction in both (CBR) value and (T.S.S) with the time. Keywords: Strength, Rice husk ash, Total soluble salts, Durability, Calcium chloride منبع: [Hidden Content] دانلود: [Hidden Content].,%204%20(5)%20492-500,%202014.pdf J. Civil Eng. Urban., 4 (5) 492-500, 2014.pdf

Improvement of Clayey Soil Characteristics Using Rice Husk Ash Original Article, C3 Mohammed Y. Fattah, Falah H. Rahil, Kawther Y. H. Al-Soudany. Journal. Civil Eng. Urban. 3(1): 12-18. 2013 ABSTRACT: Rice husk ash (RHA) is a pozzolanic material that could be potentially used in soil stabilization, though it is moderately produced and readily available. When rice husk is burnt under controlled temperature, ash is produced and about 17%-25% of rice husk’s weight remains ash. This paper presents the results of experimental study carried out on three different soils improved with different percents of rice husk ash. Samples were brought from different sites of Iraq. The testing program conducted on the clayey soil samples mixed with different percentages of rice husk materials, included Atterberg limits, specific gravity, compressibility, unconfined compression test and consolidation test. It was found that the liquid limit of the three soils has been decreased by about (11 - 18) % with the addition of 9% RHA, while the plasticity index decreased by about (32 - 80) %. Treatment with rice husk showed a general reduction in the maximum dry unit weight with increase in the rice husk content to minimum values at 9% rice husk content. The optimum moisture content generally increased with increase in the RHA content. There is enormous increase in the unconfined compressive strength with increase in rice husk content for the soil to its maximum at RHA between (6 – 8) %. Keywords: Clayey soil, improvement, rice husk ash, strength. منبع: [Hidden Content] دانلود: [Hidden Content],%203(1)%2012-18.pdf JCEU-2013-C3, 3(1) 12-18.pdf

Cost Implication of Mitigating the Effect of Clay/Silt Content of Sand on Concrete Compressive Strength Oiginal Article, B25 Olanitori LM. J. Civil Eng. Urban. 2(4): 143-148. 2012. ABSTRACT: In Nigeria, reinforced concrete is one of the major building materials been used in the construction of buildings. In the specification of concrete, prescribed mix is normally used. However, tests carried out on different batches of concrete produced, using prescribed mix 1:2:4 of concrete show that the concrete did not acquire the 20N/mm2 expected strength at the age of 28 days. Depending on the type of sand used for the production of the concrete, the acquired strength after 28 days is between 25% and 60% of the expected strength. This reduction in strength will ultimately affect the functionality and durability of structure constructed from such concrete. To mitigate the effect of clay/silt content of sand, the sand can be washed free of clay/silt or the cement is increased in proportion to the percentage content of clay/silt in the sand. Since the mitigation of the clay/silt content of sand on concrete strength comes with extra cost, there is need to determine this cost in other to be able to build effective and safe structures. The author evaluates the cost implication of mitigating this reduction effect of the type of sand used on concrete strength. The extra cost incurred in the production of 1m3 of concrete (using mix ratio 1:2:4) in terms of washing the sand free of clay/silt is 22.5%, while that of cement increment is between 2.22% and 27.75% depending on the percentage of clay/silt content of sand. Mathematical models, which can be used to estimate the cost implication of this mitigation, are derived. Keywords:Reinforcement, Concrete, Sand, Silt, Strength منبع: [Hidden Content] دانلود: [Hidden Content],%20B25.pdf JCEU, B25.pdf