प्रौद्योगिकी ( Technology - टेक्नोलॉजी ) क्या है?
2023-10-08 06:31:23<p>अनुपयोगी वस्तुओं से उपयोगी वस्तुओं को बनाने वाले ज्ञान को ही<strong> प्रौद्योगिकी या टेक्नोलॉजी या शिल्प विज्ञान</strong> कहते हैं।</p>
द्रव्य क्या है?
2023-10-08 06:34:52<p>वह वस्तु है जिसमें द्रव्यमान होता है स्थान घेरा जाता है और जिसे हम इंद्रियों से महसूस कर सकते हैं इसी को <strong>द्रव्य या पदार्थ</strong> कहते हैं ।</p><p><strong>उदाहरण -</strong> जल , वायु , गैस , लोहा</p>
Science (विज्ञान) शब्द की उत्पत्ति कहां से हुई?
2023-10-08 06:35:16<p>अंग्रेजी शब्द science की उत्पत्ति लैटिन भाषा के शब्द <strong>Scientia (साइंटिया) </strong>से हुई है। जिसका अर्थ<strong> to know</strong> है।</p>
विज्ञान क्या है?
2023-10-08 06:38:39<p>प्रकृति के विषय में क्रमबद्ध व्यवस्थित एवं सुसंगठित ज्ञान की <strong>विज्ञान (Science) </strong>कहलाता है।</p>
प्राकृतिक नियम क्या है?
2023-11-03 12:56:38<p>संपूर्ण ब्रह्मांड एक अति विशाल निकाय है जिसकी संरचना व्यवस्था एवं कार्य योजना जिन नियमों पर आधारित है उन्हें ही <strong>प्रकृति नियम</strong> कहते हैं।</p>
Sources of stones for building construction:
2023-11-10 08:23:55<p>The stones are obtained by rocks. a rock represents definite portion of earth surface does not homogenous and do not have definite chemical composition and shape. it is known as monomineralic rock. if it contains only one mineral of it is known as the polymineralic Rock if it contains saveral minerals. Quartz, sand, pure gypsum, magnesite etc. are examples of Mono mineral crop and besalt Granite etc are examples of the polymineralic rock the various Rock forming minerals are:</p><ol><li>Augite</li><li>Chlorite</li><li>Feldspar</li><li>Hornblende</li><li>Mica</li><li>Olivine</li><li>Quartz</li></ol>
सिद्धांत क्या है?
2023-11-03 13:00:22<p>प्रयोग और प्रेक्षणों द्वारा सत्यापित परिकल्पना <strong>सिद्धांत</strong> कहलाती है।</p>
वैज्ञानिक विधि क्या है?
2023-11-03 12:58:09<p>वैज्ञानिक विधि के चार चरण हैं -</p><ol><li><strong>प्रेक्षण</strong></li><li><strong>परिकल्पना</strong></li><li><strong>प्रयोग</strong></li><li><strong>निष्कर्ष</strong></li></ol>
भौतिकी क्या है?
2023-11-03 13:00:59<p>विज्ञान की वह शाखा जिसके अंतर्गत द्रव्य, ऊर्जा तथा उनकी अन्तक्रियाओं का पारस्परिक क्रियाओं का अध्ययन किया जाता है ।</p>
E = mc2 क्या है?
2023-11-03 12:59:05<p>E = mc2 यह आइंसाइन का द्रव्यमान ऊर्जा संबंधित समीकरण है।</p>
ऊर्जा ( Energy ) क्या है?
2023-11-03 12:59:48<p>जिस कारण हमें वस्तुओं का कार्य करने की क्षमता प्राप्त होती है, उसी को ही <strong>ऊर्जा</strong> कहते हैं।</p><p><strong>उदाहरण</strong>- ध्वनि ऊर्जा , उष्मीय ऊर्जा , प्रकाश ऊर्जा , चुंबकीय ऊर्जा , रासायनिक ऊर्जा , नाभिकीय ऊर्जा आदि।</p>
Types of cement
2023-10-03 03:36:35<p>The different types of cements are:</p><ol><li>Ordinary Poland cement.</li><li>rapid hardening cement.</li><li>Quick setting cement.</li><li>high Alumina cement.</li><li>low heat cement.</li><li>sulfate resisting cement.</li><li>Portland pozzolana cement.</li><li>white cement.</li><li>coloured cement.</li><li>Portland slag cement.</li></ol><h3>Ordinary portland cement (OPC):-</h3><p>This cement is used for normal concrete construction like Road pavements, RCC structures and water tanks. it is manufactured by fusing together a mixture of limestone and clay in correct propertion at high temperatures the resulting product is grinded Finally with a small quantity of gypsum to delay the setting action. it setting time should be in between 30 minute to 10 hours.</p><h3>Rapit hardening cement:-</h3><p>This cement is similar to OPC but with higher percentage of tricalsium silicate and its finer than OPC but the final strength is almost the same the setting time is same as OPC.</p><p>This cement is used where a rabbit development of strength is desired it is achieved by a higher rate of heat of hydration so it is not suitable for mass concreting.</p><h3>Quick setting cement:-</h3><p>This cement sets much faster than OPC its setting ranges between 5 minutes to 30 minutes this cement is produced by adding small percentage of Aluminium Sulphate and by finally grinding the cement it is used for making concrete that is required to set early as for laying under water or in running water.</p><h3>High alumina cement:-</h3><p>It is manufacturerd by fusing together a mixture of limestone and bauxite in correct proportions at high temperature resulting product is grinding finely its initial and final schedule times are same as those of OPC it can be used in low temperature conveniently the colour of this cement is black it is more costly than OPC.</p><h3>Low heat cement:-</h3><p>This cement is manufactured by increasing the proportions of c2s and decreasing the proportion of c3s and C3 A this cement is less reactive than OPC its initial and final setting times are 60 minutes and 10 hour respectively it is unstable for ordinary structure.</p><h3>Sulphate resisting cement:-</h3><p>This cement is manufactured by from well granulated slag (80% to 85%) and Calcium sulphate (10% to 15%) along with 1% to 2% of OPC it is generally used in construction of marine works, mass concrete and for underground water works.</p><h3>Portland slag cement:-</h3><p>This cement is made by inter grinding finely the mixture of clinkers, gypsum and granulate slag in proper proportions thid cement is less reactive than OPC the heat generated is less than OPC it can be used for Marine works.</p><h3>Portland pozzoloana cement:-</h3><p>This cement produce less heat of hydration and more resistant to sulphate attack. this cement can be used in Marine work and mass concreting. it is manufactured by integrinding clinkers and pozzolana with the addition of gypsum.</p><h3>White cement:-</h3><p>It is pure white coloured cement. it poses same properties as those of OPC in this cement, iron oxide percentage is very less this is why its colour is not greyish but white in. its manufacture white chalk and clay free from iron are used oil fuel is used in place of coal for burning of the cement it is generally used for decorative purposes.</p><h3>Coloured cement:-</h3><p>It is manufactured by adding suitable minerals pigments to ordinary cement at the time of grinding chromium oxide pigment give green colour. Cobalt gives blue colour, and oxide in different proportion gives brown, red or yellow colour.</p>
Properties of cement
2023-10-03 03:38:41<p>The properties of a good cement, which primarily depend upon its chemical composition, throughness of burning and Fineness of grinding are:rn1. It's gives strength to the missionary. rn2. It is an excellent binding material. rn3. it is easily workable. rn4. it offers good resistance to the moisture. rn5. it poses a good plasticity.</p>
Cement, and raw materials for cement
2023-10-03 03:39:39<p>Cement is a binding material, which is used in construction industry. it is obtained by pulverizing clinkers formed by calcination of raw materials primary consisting of lime (CaO),silica (SiO2), Alumina (Al2O3), and iron oxide (Fe2O3). the basic raw materials used in the manufacture of portland cement are argillaceons and calcareous substances. Calcareous materials are limestone, Chalk, Marine shells etc. And argellaceous materials are shale and clay the last furnace slag etc.</p><p><strong>RAW MATERIALS FOR CEMENT:- </strong>RAW MATERIAL RANGE℅</p><p> CaO 60-70rn SiO2 17-25rn Al2O3 3-8rn Fe2O3 0.5-6.0rn MgO 0.1-4.0rn Alkalies 0.1-1.3rn Sulphur 1-3</p>