Durability of calcium-aluminate based binders for rapid repair applications

Lute, Racheal Dawn

Durability of calcium-aluminate based binders for rapid repair applications

Date

2016-05

Authors

Lute, Racheal Dawn

Abstract

Within the last few decades, the amount of vehicle miles traveled within the US has increased approximately 40% with the construction of new roads only increasing 4% during this same time period. This dramatic increase in traffic on existing infrastructure has led to the rapid decline of the condition our nation’s roads resulting in the increased need for maintenance and repair. Rapid hardening repair materials are in high demand for these applications as they allow for minimal traffic delays and road closures. Calcium aluminate cement (CAC) is a rapid hardening binder that is used for specialty applications where high early strength and increased durability are desired. In recent years, blended cement systems incorporating both CAC and calcium sulfate (C $) w i t h p o r t l a n d c e m e n t (P C) h a v e b e e n d e v e l o p e d t o u t i l i z e t h e r a p i d h a r d e n i n g c h a r a c t e r i s t i c s o f C A C b u t a t a r e d u c e d c o s t . W h i l e t h e d u r a b i l i t y o f C A C i s w e l l r e s e a r c h e d a n d d o c u m e n t e d, t h e d u r a b i l i t y o f t h e s e n e w b l e n d e d s y s t e m s i s n o t y e t f u l l y u n d e r s t o o d . T h e f o c u s o f t h i s r e s e a r c h w a s t o e v a l u a t e t h e p e r f o r m a n c e a n d l o n g t e r m d u r a b i l i t y o f v a r i o u s b l e n d e d s y s t e m s w h i c h u t i l i z e C A C o r c a l c i u m s u l f o a l u m i n a t e c e m e n t (C S A) t o a t t a i n r a p i d h a r d e n i n g . M o r e s p e c i f i c a l l y, t h e s e s y s t e m s w e r e e v a l u a t e d t o d e t e r m i n e t h e i r r e s i s t a n c e t o c o m m o n m o d e s o f c o n c r e t e d e t e r i o r a t i o n s u c h a s a l k a l i − s i l i c a r e a c t i o n, e x t e r n a l s u l f a t e a t t a c k, d e l a y e d e t t r i n g i t e f o r m a t i o n, c a r b o n a t i o n, a n d c o r r o s i o n i n m a r i n e e n v i r o n m e n t s t h r o u g h i n − s i t u l a b m e t h o d s a n d l a r g e s c a l e o u t d o o r e x p o s u r e . T h e r e s u l t s o f t h e t e s t i n g c o n d u c t e d r e l a t e d t o a l k a l i − s i l i c a r e a c t i o n, e x t e r n a l s u l f a t e a t t a c k, a n d d e l a y e d e t t r i n g i t e f o r m a t i o n i d e n t i f i e d t h e p o t e n t i a l f o r l a r g e l e v e l s o f e x p a n s i o n i n b l e n d e d s y s t e m s o f P C : C A C : C$ and PC:CSA. Details regarding each mode of deterioration and mechanisms of expansion are discussed.