Polikarboksilat-bazlı süperakışkanlaştırıcıların silis dumanı içeren çimento hamurlarının reolojik davranışına etkileri

Yıl 2019, Cilt: 25 Sayı: 6, 627 - 634, 25.11.2019

Sıddıka Gamze Erzengin

Öz

İnşaat
sektöründe üstün özelliklere sahip çimento-esaslı yapı malzemelerine olan
ihtiyaç gün geçtikçe artmaktadır. Bu çalışmada, beton karışımlara yüksek oranda
akışkanlık sağlayan yeni nesil polikarboksilat-bazlı süperakışkanlaştırıcıların
farklı türevleri sentezlenmiş, karakterize edilmiş ve silis dumanı içeren
çimento hamurlarında performansları test edilmiştir. Farklı moleküler yapılara
sahip bu polimerlerin çimento hamurlarının akışkanlık özelliklerine etkileri
mini-çökme ve reoloji deneyleri ile araştırılmıştır. Reolojik davranışların incelenmesinde
Bingham ve Herschel-Bulkley olmak üzere iki farklı model yaklaşımı
kullanılmıştır. Süperakışkanlaştırıcı yapısında fumarik asit gibi bir
dikarboksilik asit bulunmasının hamurların işlenebilirliğinde ve bu
işlenebilirliğin zamana bağlı korunumunda etkileri olduğu gözlenmiştir.
Sentezlenen süperakışkanlaştırıcıların hamur yayılma çapını katkısız hamura
göre %100’ün çok üzerinde arttırdığı ve karışımların zamana bağlı (2 sa.) etkin
akışkanlık davranışı için tercih edilebileceği belirlenmiştir. Ayrıca bağlayıcı
olarak sadece çimento içeren harçlarla karşılaştırıldığında, söz konusu
süperakışkanlaştırıcıların çimento ve silis dumanlı harçlarda mekanik
dayanımları geliştirdiği görülmüştür. Sonuç olarak, sentezlenen yeni nesil
polikarboksilatların yüksek performanslı beton üretimlerinde kullanılma
potansiyelinin bulunduğu anlaşılmıştır.  

Anahtar Kelimeler

Polikarboksilat, Silis dumanı, Çimento, Reoloji, Dayanım

The effects of polycarboxylate-based superplasticizers on the rheological behaviours of cement pastes containing silica fume

Öz

In
construction sector, the necessity to cement-based materials having superior
properties is increasing day by day. In this study, novel forms of new
generation polycarboxylate-based superplasticizers which provide higher
fluidity to concrete mixtures were synthesized, characterized and their
performances in cement pastes containing silica fume were tested. The
influences of polymers possessing different molecular structures on the flow
properties of cement pastes were investigated with mini-slump and rheology
tests. Two different model approaches as Bingham and Herschel-Bulkley were used
to examine rheological behaviours. It was observed that, the existence of dicarboxylic
acid as fumaric acid in superplasticizer structure have effects on pastes’
workability and the time-dependent retention of this workability. It was
determined that, synthesized superplasticizers increase the flow diameter of
paste over 100% than plain paste and can be preferable for the effective
fluidity behaviours of mixtures by time (2 hours). Additionally comparing with mortars containing only cement as
binder, it was seen that superplasticizers in question improve the mechanical
strengths of mortars possessing cement and silica fume. As a result, it was
understood that the synthesized new generation polycarboxylates have potential
to be used in high performance concrete production.

Anahtar Kelimeler

Polycarboxylate, Silica fume, Cement, Rheology, Strength

Kaynakça

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