A study on the influence of curing on the strength of a standard grade concrete mix

Abstract

Curing is essential if concrete is to perform the intended function over the design life of the structure while excessive curing time may lead to the escalation of the construction cost of the project and unnecessary delays. Where there is a scarcity of water and on sloping surfaces where curing with water is difficult and in cases where large areas like pavements have to be cured, the use of curing compound may be resorted to. The parameters of the study include the curing period [1, 3, 7, 14 and 28 day], curing method [conventional wet curing, membrane forming compound curing and accelerated curing] and the type of cement [Ordinary Portland Cement(OPC) 43 grade, Portland Pozzolana Cement(PPC) 43 grade and Ordinary Portland Cement(OPC) 43 grade +10% Silica Fume(SF) replacement for cement]. In all a total of 99 cube specimens were cast and cured under different conditions before testing. Test results indicate a drop in strength at all ages for concretes with PPC and the one in which 10% OPC is replaced by silica Fume(SF) in comparison with the concrete with OPC. Curing by membrane forming curing compound yielded nearly the same results as that of conventional wet curing for concrete with OPC and there was a marginal decrement in concrete with PPC. Predicted 28-day strength of concrete from the accelerated curing test was found to be on a conservative side compared to control concrete.Nega je neophodna kako bi beton obavljao svoju funkciju za projektovani vek konstrukcije, dok prekomerna nega moze dovesti do povecanih troskova projekta i nepotrebnog zadrzavanja. Tamo gde je nestasica vode kao i na nagnutim povrsinama gde se nega betona vodom obavlja tesko i u slucajevima gde se nalaze velike povrsine, poput plocnika koje treba negovati, moze se pribeci koriscenju jedinjenja za negu betona formiranjem membrane. Parametari studije obuhvataju periode nege od 1, 3, 7, 14 i 28 dana, metode nege (konvencijalna nega kvasenjem vodom, nega jedinjenjem koje formira membranu i ubrzani tretman) i vrste cementa (Obican Portland cement (OPC) 43 klase, Portland cement Pucolan (PPC) 43 i obican Portland cement (OPC) 43 klase+10% silikatne prasine (SF) kao zamene za cement. Ukupno 99 uzoraka kocke su izliveni i negovani pod razlicitim uslovima. Rezultati testa ukazuju na pad cvrstoce u svakom starosnom dobu betona sa PPC i u onoj kojoj je 10% OPC zamenjeno silikatnom prasinom (SF) u odnosu na beton sa OPC. Nega sa membreno folijom dala je skoro iste rezultate kao kod konvencionalne mokre nege za beton sa OPC i doslo je do marginalnih smanjenja u betonu sa PPC. Predvidjene 28-dnevne cvrstoce betona testa ubrzane nege su bile konzervativne u poredjenju sa kontrolnim betonom.