Search or add a thesis

Advanced Search (Beta)
Home > Variation in Properties of Different Pakistani Cements and its Effect on Properties of Concrete

Variation in Properties of Different Pakistani Cements and its Effect on Properties of Concrete

Thesis Info

Access Option

External Link

Author

Qureshi, Liaqat Ali

Program

PhD

Institute

University of Engineering and Technology

City

Taxila

Province

Punjab

Country

Pakistan

Thesis Completing Year

2010

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/1030

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727657130

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


This research work pertains to study the impact of variations in characteristics of various brands of cement available in Pakistan on the properties of concrete namely, the workability and compressive strength. The main aim was to study the trends of cement using indigenous raw materials and its effect on resulting concrete. Fineness/Blaine values were considered as the key property of cement and its effect on properties of concrete and other cement properties was investigated. Fineness of cement has substantial effect on the properties of fresh and hardened concrete. It is an established fact that the finenesses of Portland cements have increased during the past 50 years and are continuing to increase. Various researchers conducted detailed investigations on the effect of fineness of cement on properties of concrete. Fineness/blaine values were varied by grinding cement clinker with gypsum at laboratory ball mill level and its effect on properties of mortar and concrete was observed. In order to generalize the result, investigation was conducted and averaged over five cement factories. Fresh cement clinker collected from selected batch of each factory was ground with 4% gypsum in a laboratory ball mill. During grinding, fineness was periodically measured using Blaine’s air permeability apparatus. In this way, six cement samples with different fineness values were prepared from each factory. In order to confirm uniformity of their oxide ratios, chemical composition of sample was analyzed by XRF-Cement Spectrometer. Grinding time for each sample was recorded by the built-in timer of ball mills. A comprehensive testing was carried out on cement samples prepared in this way. Comparisons were made between (a) fineness of cement versus consistency, setting time and compressive strength of cement, (b) slump and compressive strength of concrete, (c) Heat of hydration and TG loss measured by DTA/TGA tests and (d) grinding time utilized in preparation of samples in the laboratory ball mill to make relative study of cost of grinding against desirable properties of mortar & concrete at higher fineness levels. The consistency of cement as well as compressive strength of mortar cubes and concrete increase while setting time decreases with increasing fineness of cement. The results obtained are well in accordance with the previous vpublished data made on foreign cements. A fineness of 3200 cm 2 /g has been recommended as optimum value. Up to this value, increase in strength is more and grinding cost is less. However, after this value, grinding cost increases while rate of gain of strength ceases. However, an interesting pattern was noted regarding fineness versus workability for samples from almost all the sources. Workability of concrete increases with fineness up to 2500 cm 2 /g then it remains constant for fineness up to about 3200 cm 2 /g. Afterwards it again starts increasing. In the case of projects where high workability is needed, fineness may be raised above 3400 cm 2 /g but keeping in mind that it is involved with high grinding cost, thus, making cement uneconomical. So, other techniques e.g., use of admixtures to improve workability, may be more economical.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

اُس نے بھی کیا چاہے وہ اقرار نہیں تھا

اُس نے تو کیا چاہے وہ اقرار نہیں تھا
ایسا بھی نہیںمجھ سے اُسے پیار نہیں تھا
اب شکل مری مجھ سے بھی تو ملتی نہیں ہے
ایسا تو کبھی مَیں اے مرے یار نہیں تھا

مولانا غلام اللہ خان کی تفسیر جواہر القرآن: منہج اور خصوصیات

Maulana Ghulamullah khan is considered one of the best commentators of the Quran from  Punjab. Ghulamullah Khan was born in 1905 in Chaj Darya, Attock district of Punjab. He got his Quranic education from Maulana Rashid Ahmad Gangohi, who was a disciple of Maulana Hussain, a well-known and a leading commentator of the Quran. He studied hadith  from Hussain Ahmad Madni, Maulana Shabir Ahmad Usmani and Anwar Shah Kashmeri. This tafseer consists of fifteen hundred pages. It has a long preface and covred up in three volumes over all. Maulana Hussain Ali named him a true successor of the Quranic studies and acknowledged that he had done this duty well. Among his works, TAFSEER JAWAHIR -UL- QURAN, has its own uniqueness and usefulness. Millions of copies have been published of this Tafsier. This tafseer is a compilation of rabat bain surulayat (connection between sura and ayat) of  Maulana Hussain Ali by Ghulamullah khan and has been revised by Maulana Said Ahmad Hussain Sajad Bukhari.  He is termed as Shaikh ul Quran and was called so by Maulana Hussain Ali.I have hinted at different sources for my article so that readers may expand their knowledge about the Quran and Tafseer. This article is about JAWAHIR -UL- QURAN and it will throw light on its features.

Adverse Health Experiences, Risk Perception and Pesticide Use Behavior

For Pakistan’s economy, agriculture is the most important sector. It contributes about 22 percent of the gross domestic product (GDP) and employs 45 percent of the national employed labour force. It supports directly or indirectly about 65 percent of the population living in rural areas for their sustenance. It also contributes about 65 percent to total export earnings derived from raw and processed agricultural commodities. It is evident that pesticides are used for the benefits. However, use of pesticide leads to negative externalities for the farmers and the society. Negative externalities may include such as effects on human health, loss of bio-diversity, degradation of natural ecosystems and irreversible changes in the environment. Various kinds of pesticides have been used on a large scale in Pakistan since the early 1950s to protect crops from damages inflicted by insects and diseases. After liberalization of pesticides in 1980, pesticide use increased dramatically in Pakistan reaching 117513 metric tonnes in 2005 which was only 12530 metric tonnes in 1985. The massive increase in pesticide consumption is not translated into productivity improvements rather accompanied by a huge cost in terms of human health and degradation of the environment. It is well established that the use of pesticides on the farm is largely governed by voluntary behavior. Therefore, it is important to understand what drives farmer’s behavior of pesticide use. Such information is critical to identify the prospects and constraints to the adoption of alternative crop protection policy. According to microeconomic consumer theory, individuals make choices following their preferences. However, economic theory does not focus to the processes of individual’s reasoning behind choices. Cognitive models in Public Health and Social Psychology argue that persons who have had adverse health experiences are likely to undertake greater preventive behavior. This study combines an approach from social psychology with micro economic consumer theory to understand individual’s reasoning behind their decisions. Further, it also examines the health implications of pesticide use as caused by behavior of the farmers which help to inform policy makers about productivity reducing effects of pesticide use. A survey of 318 farmers in Vehari and Lodhran districts of Southern Punjab was drawn. Results indicate that farmers are frequently exposed to pesticides. Over 90 percent farmers reported at least one health problem in district Lodhran, where as in district Vehari, almost 80 percent farmers reported the same. However, they appeared to give low priority to health considerations and grossly under-estimating pesticide’s health risk where almost all the farmers did not visit hospital or doctor for proper medication. This misperception is largely translated into practical behavior where farmers were found heavily skewed towards pesticide use for pest management and the use of protective measures to avoid direct exposure of pesticides is not sufficient. Low level of education combined with cultural/local beliefs regarding health effects of pesticide use is the main reason of this comportment. Moreover, about 80% pesticides used in the study area are highly or moderately hazardous. In terms of crops, cotton alone received over 70% of total quantity. Similar pattern appeared in terms of toxicity, where cotton consumed over 88% of highly hazardous and moderately hazardous pesticides. Farmers were found to be overusing pesticides. They were also found applying pesticides very frequently. During survey 73 percent of them reported that they applied pesticide more than 10 times on cotton in a season. The spray frequency is as high as 16 on cotton crop in one season. There is a dearth of formal training and information on proper use and safe handling of pesticides. Most of the farmers did not know about IPM, hardly few of them using it which helps them reduce dependence on pesticides. The analysis supports the hypothesis that farmers who have had negative health experiences related to pesticide use are more likely to have heightened risk perceptions than farmers who have not had such problems. Education and training are also important determinant of risk perception. Association also existed between the experience of health problems and the use of protective measures. The results, however, do not support the hypothesis that the farmers who have had negative health effects from pesticide use are more likely to adopt alternative pest management practices. This however does not mean that farmers who have had such experiences do not care about the effects of pesticide use. The lack of information or access to alternative pest management practices is the likely reason. The Contingent Valuation (CV) analysis shows that farmers are willing to pay premium for safe alternatives of pesticides which support our argument. Finally, research findings have some important implications, for example, the empirical relation that appears to exist between training of safe handling and alternative pest management would suggest that trained farmers significantly and effectively substitute IPM for pesticide use. Hence, to improve awareness, necessary for better choices of pesticide use, specific and relevant information regarding the health effects and environmental risks of using pesticide should be provided to farmers through training programs. For this, government should restructure current pro-pesticide extension system and design effective outreach programs, such as farmer field schools which deal specifically with health risk of pesticide use, averting behavior and better management of pests. One such program (e.g. National IPM program) is already in place but with limited coverage which needs to be strengthened and broadened through increased efforts by government and NGOs to educate farmers which may help reduce dependency on pesticide while at the same time maintaining or improving production. Further, policy interventions should also include the restructuring of incentives and punishment to reduce availability of highly toxic insecticides.