Effect of Internal Curing on Freeze–Thaw Durability of Dry-Cast Concrete Segmental Retaining Wall Units and Solid Interlocking Concrete Paving Units

Masonry 2014 ◽  
2014 ◽  
pp. 70-97
Author(s):  
Craig Walloch ◽  
Jeff Speck ◽  
Laura Powers
Author(s):  
Cesar T. Chan ◽  
Kenneth C. Hover

Segmental retaining walls (SRWs) constructed of dry-cast concrete masonry units are used in transportation-related applications for which freeze-thaw (FT) durability is evaluated on the basis of percent mass-loss accumulated after multiple FT cycles as per ASTM C1262. This study compared mass loss, mass gain owing to absorption during (FT) exposure, and relative dynamic modulus (RDM) as per ASTM C215. Application of RDM required accounting for the influence of the shape and moisture content of SRW coupons on resonant frequency, with corrections that are likewise applicable to ASTM C666 for ordinary concrete. It was demonstrated that mass loss does not exclusively indicate surface damage, and the relationship between mass loss and RDM is unique to each specimen. Mass gain (as moisture absorption) during testing emerged as a key index of damage, with rapid escalation of mass loss and reduction in RDM at the number of FT cycles required to increase the moisture content of the residual coupon by about 1%.


2007 ◽  
Vol 34 (11) ◽  
pp. 1413-1423 ◽  
Author(s):  
S. E. Chidiac ◽  
H. Zibara

Performance of dry-cast concrete masonry products (DCCMPs), which are becoming the product of choice for many applications, has yet to be assessed in a comprehensive manner. This study was undertaken to investigate the effects of mix design and manufacturing parameters on the mechanical and transport properties, as well as the freeze–thaw (F/T) durabilities, of DCCMPs. The variables studied were water to cement ratio, mixing time, vibration time, and curing regime. Freeze–thaw durability was assessed in accordance with the American Society for Testing and Materials (ASTM) standard C1262 by exposing specimens to four conditions: water, 3% NaCl, 4% CaCl2, and 4% MgCl2 solutions. Results revealed that 3% NaCl exposure yielded the most mass loss due to scaling, whereas 4% MgCl2 exposure exhibited the least. Increase in either water content, vibration time, mixing time, or use of moist curing led to improvement in the mechanical properties, refinement of large pores in the range of 40 to 400 μm, reduction of total porosity, and enhancement of F/T durability of capstones. Ionic sorptivity yielded a strong statistical correlation with mass loss due to F/T action in the presence of 3% NaCl and 4% CaCl2.


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