In today’s world, the implementation of industrial ecology for sustainable industrial development is a common practice in the field of engineering. This practice promotes the recycling of by-product wastes. One of those by-product wastes is rice husk ash. This paper describes an investigation into the effect of rice husk ash (RHA) as a partial replacement for cement, to produce lightweight, aerated concrete. Type I Portland cement, fine aggregate, and aluminum powder as an aerating agent were used in this study. The RHA was used in different replacement levels, i.e., RHA was used to replace cement at 0%, 2.5%, 5%, 7.5%, 10%, 12.5% and 15% by weight. Aluminum powder was added during mixing at 0.5% by weight of binder to obtain lightweight, aerated concrete. Test results are presented in terms of physical, mechanical, and durability aspects that include density, compressive strength, split tensile strength, and flexural strength of concrete cured at different curing regimes, i.e., 3, 7, 28, and 90 days along with corrosion analysis, and sulphate attack at 28 days of curing. The test results show that using 10% RHA as a partial replacement of cement in aerated concrete is beneficial in triggering the strength and durability properties of concrete.
The carbon dioxide emissions from Portland cement production have increased signi cantly and Portland cement is the main binder used in self-compacting concrete, so there is an urgent need to nd environmental friendly materials as alternative resources. In most developing countries, the availability of huge amounts of agricultural waste has paved the way for studying how these materials can be processed into self-compacting concrete as binder and aggregates compositions. Therefore, this experimental program was carried out to study the properties of self-compacting concrete (SCC) made with local metakaolin, coal bottom ash separately and combined. Total 25 mixes were prepared with four mixes as 5,10, 15 and 20% replacement of cement with metakaolin, four mixes as 10, 20, 30 and 40% of coal bottom ash as partial replacement of ne aggregates separately and 16 mixes prepared combined with metakaolin and coal bottom ash. The fresh properties were explored by slump ow, T 50 ow, Vfunnel, L-box, J-Ring sieve segregation test. Moreover, the hardened properties of concrete were performed for compressive, splitting tensile and exural strength and permeability of SCC mixtures. Fresh concrete test results show that even if no viscosity modi er is required, satisfactory fresh concrete properties of SCC can be obtained by replacing the ne aggregate with coal bottom ash content. At 15% replacement of cement with local metakaolin is optimum and gave better results as compared to control SCC. At 30% replacement of ne aggregate is optimum and gave better results as compared to control SCC. In the combined mix 10% replacement of cement with metakaolin combined with 30% replacement of ne aggregate with coal bottom ash is optimum and gave better results as compared to control SCC.
Concrete durability is a key aspect for forecasting the expected life time of concrete structures. In this paper, the effect of compressive strength and durability of concrete containing metakaolin developed from a local natural material (Soorh of Thatta Distict of Sindh, Pakistan) is investigated. Soorh is calcined by an electric furnace at 8000C for 2 hours to produce metakaolin. One mix of ordinary concrete and five mixes of metakaolin concrete were prepared, where cement is replaced by developed metakaolin from 5% to 25% by weight, with 5% increment step. The concrete durability was tested for water penetration, carbonation depth and corrosion resistance. The obtained outcomes demonstrated that, 15% replacement level of local developed metakaolin presents considerable improvements in concrete properties. Moreover, a considerable linear relationship was established between compressive strength and concrete durability indicators like water penetration, carbonation depth and corrosion resistance.
Temperature and precipitation variations have a huge environmental, social and economic impact. This study aims to analyze the temporal variation of temperature and precipitation in Shaheed Benazir Abad district by using the linear regression method, the trend magnitude, the Mann-Kendall test and the Sen’s estimator of slope. The annual precipitation and monthly temperature data of Shaheed Benazir Abad for the period of 1996-2014 are considered. The result shows that the Diurnal temperature range of all months is decreasing due to the increasing of monthly minimum temperature at a faster rate than the monthly maximum temperature. However, the Diurnal temperature range of extreme events is increasing. The results obtained by using Mann-Kendall test revealed that rainfall exhibits significant positive trend. The trends of rainfall and rainy days show that the amount of rainfall is increasing much more rapidly than that of rainy days which indicates the occurrence of heavy events.
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