CEE Oct-Dec 2002

cnncrctl ro<Jds. In France concret..: i-... <!•l ining. market <;hare for low le\ ..:1 tr~1nic macb. In Ireland tracks and pl'lks trian ;m.::1s <~re buil l u ~ in g co1H:retc. In Italy concrete pavins inside the tunnels will be enforced h~ a 11e'' :,t;mdard. Both in Norw<~y and S'' etkn c~1st in-situ (concrete) '>Oiutions ;m: prekrred for ro<~ds. Concrete is just entering the market in Poland where around 200 km o r new molorways will be built in co ncrete. Conc rete is used as shotcrete and as paving materi<~l in tunnels in Slovakia. In Spain the new high-speed tracks will be constructed using n co ntinuous conc rete slab. In Turkey a 1.5-km long concrete road has been bui It b) tht> re <~dy mixed co ncrete producers to sho\\ the advantages of co ncre te road s. In England concrete roads are not common. In Turkey two concrete roads \\ill be constru cted by TCMB accord ing to a protocol signed with Cicncral Directory of llighways. Cnwtesr : Cement & Concrete ll"orld (.frmmol o(TCMA). .lul-:l ug 02. !' -II . Fux : (CJ0312) 28-92"'2 f:muil: inji:J 1 a ICIIW.orgtr lf"eh: ll"l\"IV.tCIIW.OI"g./r FOOTPATH DEVELOPMENT PROJECT 'l"l!c Hindu Business Line. /Jungulnre, 25. I0. 2002 Bangnlo re · s pavements will \\car a ne\\ look soo n wi th the 13<~ngalore City Corporation (BCC) proposing to implement a footpath de,·elopment project at a cost of Rs. 70 cron.:. Tile B<mg:alore ci ty ivlayor. Mr. I<. Chandrashckhar sa id the BCC \\l)tild request the BE. CO 1 and the Telecom Depanment to inst:lll duc t~ for laying cables to avoid road c ultings, "hich will hamper till: footpath de,·clopment plan. As part nr th is programme, all kinds or e ncroad1menh on 1hc footpath inc ludin g gardens \\Oulcl be removed, he sa id. Cnurfl.::,~\ ' · Cement Neil'S Dig,ust. /lJ-25 Oc! 0]. P 12 Fax: 021-] ]{J-/0582 Email: cmabhlu hom]. vsnl.nel.in IVeh: 11'11'\I'.C117llllldia.org LONG-TERM DURABILITY STUDIES WITH PORTLAND SLAG CEMENT Torik Md eta/. in ?"CANMET/AC! Seminar on "Pe1:frmnunce c~l F~\' !hh, Silica Fume and Slug .. at Che111wi. India, 200 I . Marine durability o f I:" -- year old plain and reinforced concrete is prese nt ed here. Pl ain and reinrorce cl co nc rete cylindrica l specimens of diame ter 150 mm :.llld height 300 mm were investigated. T he specimens ''ere m.1Je with: • OPC • Slag Cement Type A (SCI\) - Slag Content = 5 - 30% Type B (SCB)- Slag Content = 30- 60°/cl Type C (SCC) - Slag Content = 60-70% e f I y Ash ('eme111 Type B (f.ACI1) W/C ratios "ere 0.45 and 0.55. Both tap and ~ea"·;ner "ere used as mixing " ·ate r. Us ing the se variab les. pla in a nd co nne te spec imens o i' 20 CaSe!> eac h \\cl"C investig:lled after cxpo~ urc in a tidal pool of 15 yea rs. Stee l bars of 9mm diamete r were embedded at cover dept h or::W.-10 and 70 mm. ( "omJJrel!ensive /·\frength: Re lat ive ly hi ghe r strengths were observed ror IO\\er W/C ra tio irrespective or the type or cement and age o r exposure. Compared to the strengt h at 2Sdays, a gain in Strength \\'3S obse rved fo r OPC. SC;\, SCR and SCC. II 0" ever. a reduction in strength was observed 68 in em,~ or I ACH. ( · Ll,. hul/ cl/ /IJ/i Carbonation depth~ Dt:Jllil (1f the specimens \\Crl' negligible irrespective of the type~ of cement. ( "hloride loll ( 'onc:t!ntrotioll.\ Concrete mi.\cd "ith sea\\ ater had higher chloride- ion concentration" a compared to the concrete mixed '' ith tap water. II igher W /C r;1t 10 show~d higher <~mount of chloride ion concentration. Relative!; mor..: chloride ions "ere penetrated at hi gher depth in conc rete with OI'C compared to SCA. SCIL SCC and FACB. Corroded .-I reo and Numhcr nf ?its. Alu.ri11111111 Pit ()('fJth ofl(/ l)1t Volume: For a :20-mm CO\ er concrete. corroded area was the highest for FACB. Slag Cements s howed th e best performance against corrosion of stee l bars. In case or sec, the corroded a reas were most ly concentra ted :1t the voids surrounding the stee l ba r. The use or sea\\ater as mi.\ing water increases the corrntk:d nr..:a. In general. the higher the concrete cover the lo" er the corroded area. OPC and rACB s howed more numbe r or pits as compared to ' CA, SCI3 and SCC. Lo\\ er pit depths and pit volumes \\ere observed in SCB and SCC. l li gher W/C rat io also caused an increa~e in the pit number~. 1 he U SC of <.,ea '\~lte r caused an increase in the pit depth at a cover of:20 or 40 mm. Di//11.1/1111 ( 'o-t/fich'l/1 unci T1111l' tn lnilt c/1 ,• Cnrro\lun file estimated d11rusion cn-enicie111 nml time-to- inni;ltc-corrnc..ion data an.: c;ummari/LJ bell)\\. na~ed on these da ta. chloride diffusion \\<IS ordered as OPC> FACI3 ·Sl"A · ~CI3 > SCC. The time to in itiate corrosion ":1:; assumed to be the s:1me as the ti me requi red to reach chloridcion concentration of0.-1% or cement b~ 111nss over the steel bars. It is cl~arl)' observed that i I" concrete is made '