Cement, Energy and Environment July-Sep 2002

SUSTAINABLE CONSTRUCTION IS THERE ANY ll\DIGENOU~ KNOWLEDGE ON CO~CRETE? D. Srinivasan, Secretary General, Indian Concrete Institute, Chennai l( nowledge developed by the rura l, un-educated and tribal people about health, sani tation, herbal cure, life, plants, water, wild life etc. is genera ll y te rmed as l.K . It is believed, the knowledge gained over centuries and passed on orally fo r generat ions, be it Roman Civilisation, Greek Civ ilisation, Mesopotam ian Civ ili sati on, or Indus Va lley Civi lisation. Portland Cement came to India less than a century ago. What kind ofl.K. could be avai lable in India about it. I. K. in a broader se nse, I fee l, is a know ledge deve loped by experience, by men on the job. It is only known how and not know why. Duri ng every concreting they make neat cement slurry and pour along the surfaces of the formwork and vibrate the concrete such that the thick cement slurry forms a thin coa t over the ent ire concrete surface. Th is surface wou ld be exposed on deshuttering. The slurry does neither change the proportion of the concrete mix nor the water ct:ment rati o but provides a th in coating when the concrete is wet and becomes integral with concrete and becomes part and parcel of the concrete. It neither ski n out nor peel off like any subsequent protective coating. which normally is required to be applied periodi call y if once applied. I surmi se that the in-bu ilt thick slurry in thin coating that appear on the fo rm finished surface of the concrete has rendered the concrete extremely impervious and did not allow the water that was there in the fresh concrete to evaporate and dry out the concrete and this water aided the continuous hydration. Ofcourse, the concrete was cured also well. I wanted to know if my surmi se is correct. Wi ll any will ing sc ien ti s t, research scholar come forward to study the effect of slurry fini sh on the impermeabiltty of concrete? The foremen who . la id the concrete in the way were primarily interested in getting a good fin ish, appearance. But l am inclined to beli eve that thi s has resu lted in a strong and durable concrete, as the extra water that was available in the mi x fo r curin g without getting entirely lost to the atmosphere due to evapo ration. I reques t the researche rs e ithe r to confirm or dismiss my surmise. If they confirm the n thi s l. K. on concre te will greatly help in producing a durable concrete. Courtesy: New Building Materials & Constmction World (NBAI&C'), June 02. Pp. 60-6/.Fax: 0//-6822.JI.I Email: nbmc11•Ui'nda.1•.m/. net.in RS 59,000Cr TO BE SPENT ON ROADS IN TENTH PLAN Government wiII spend about Rs 59,000 crore on development of road infrastructure during the Tenth Pl an (2002-07), mi nister of state for road transport and highways B.C. Khanduri said on Monday. Speaking at the Indo-US workshop in New Delh i, he said about Rs 45,000 crore of th is wou ld be s pe nt on the ambitious programnie of fo ur/six– lani ng 13, 146-km of nat iona l highway s whi ch is s lated fo r completion in 2007. Courte.\y: The Financial Express. 21 May. 02, P 3. BLE!\OED CE \1 F:~T SHARE RISE~ TO -U.S'~, Abinaba Das, M111nbai ·With cement makers going on the offensive to drive up ma rg ins and sh ifting customer preferences, consumption, of blended cemen t has witnessed a sharp increase in recent months. The share of blended cement, which inc ludes portland pozzolana cement (PPC) and portl and slag cement (PSC), shot up to 44.5 per cent as on March 3 I, 02, from 36 per cent a year ago. Ordinary Po rtland Cement (OPC), higher cost cement variety comp ri si ng a round 95 per cent c linke r and small quan ti ties of gypsum, now account for 56 pe r cent of the total outp ut against 62 per cent just a year ago. Blended cement, on the other hand, contai ns a far lesser sha re of cli nker, a more expensive raw material, whi ch is substi tuted by either ny ash (portland pozzolona cement) or s lag (portland s lag cement). The catch however is that with a marked shifi in consumption patte rn in favo ur of blended cements, where addit ives account fo r between I8-45 per cent, the effective cement capacity has been on a steady rise which, according to industry observers, could delay the much awaited demand-supply parity by 3-4 years. ''The consumption of cl inker today stands at 86.43 million tonnes as aga inst an ope ra ting c linker capacity of 111.53 million tonnes. What it effecti vely means that with the current quantum of clinker, the industry cement output can increase by another 2 1 million tonnes. With another 5 mi ll ion tonnes of cement capac ity on the anvi l, the demand- m