Pore structure of air-entrained hardened cement paste: Fid-Bau Portal

Pore structure of air-entrained hardened cement paste

Cebeci, Ömer Z.

AbstractThe effect of air entrainment on the pore structure of hardened cement paste was investigated. Air-entrained and air-free samples of various water-cement ratios and ages were prepared by a well-defined procedure. The first and second-intrusion pore-size distribution curves of the samples were determined by mercury intrusion porosimetry. It was observed that sample preparation technique affects the pore-size distributions of hardened cement pastes. The second-intrusion curves indicated a decrease in the total volume and a reduction in the size of pores that are uniform in cross section with decreasing age and water: cement ratio. The second-intrusion curves of air-entrained and air-free pastes of equal water: cement ratio and age matched with each other. It was concluded that air entrainment introduces only large air voids observable by a naked eye and does not alter the characteristic fine pore structure of hardened cement paste appreciably.

ZusammenfassungBünyeye hava sürükleyen katk⌝ maddelerinin sertleşmiş çimento hamurunun gözenek yap⌝s⌝ üzerindeki tesirleri araşt⌝r⌝lm⌝şt⌝r. Deǧişik su: çimento oranlar⌝nda, haval⌝ ve havas⌝ al⌝nm⌝ş hamurlar tarif edilen tarzda haz⌝rlanm⌝şt⌝r. Bas⌝nçl⌝ c⌝va porozimetresi yard⌝m⌝ ile numunelerin iki aşsamada gözenek büyüklüǧü daǧ⌝l⌝m⌝ eǧrileri elde edilmiştir. Numune haz⌝rlama tarz⌝n⌝n sonuca tesir ettiǧi gözlenmiştir. łkinci aşamada elde edilen eǧriler toplam muntazam gözenek hacm⌝nda ve muntazam gözenek büyüklüǧünde, numune yaş⌝na ve su:çimento oran⌝na paralel bir azalma olduǧunu ortaya koymaktadir. Ayn⌝ suçimento oran⌝ ve yaştaki, haval⌝ ve havas⌝ al⌝nm⌝s numunelerden ikinci aşamada elde edilen eǧriler büyük ölçüde çak⌝şmaktad⌝r. Dolay⌝s⌝yla, sürükleyici katk⌝lar⌝n sertleşmiş çimento hamurunda sadece ç⌝plak gözle görülebilen hava boşluklari meydana getirdiǧi ve sertleşmiş hamurun kendine mahsus mikro-gözenek yap⌝s⌝n⌝ dikkate deǧer ölçüde deǧiştirmediǧi neticesine var⌝lm⌝ştir.