Effects of distribution of lightweight aggregates on internal curing of concrete

Abstract This study investigates the effects of spatial distribution of lightweight aggregates (LWAs) on internal curing of concrete. As replacements for normal aggregates, different sizes and amounts of natural pumice LWAs were used as water reservoirs to provide internal curing in mitigating autogenous deformation. Water in the pre-soaked LWAs flows into cement paste during hydration and provides internal curing to counteract the RH loss due to self-desiccation of binding paste. The results show that variations in the autogenous strain of concrete can be evaluated in terms of LWA–LWA proximity. The protected paste volume approach, previously used for air-entrained concrete, is applied to calculate the internally-cured volume of paste. The results show that the experimental rate of mitigation of autogenous strain for different series of concrete specimens, with respect to the reference concrete, gave the best-fitted values at water flow distance of 1 mm. The results indicate that the protected paste volume in internal curing can be determined by calculating the water-entrained volume using image analysis.

[1]  R. Philleo.  A method for analyzing void distribution in air-entrained concrete , 1983 .

[2]  D. Bentz,et al.  Protected paste volume in concrete: Extension to internal curing using saturated lightweight fine aggregate , 1999 .

[3]  J. Müller-Rochholz.  Determination of the elastic properties of lightweight aggregate by ultrasonic pulse velocity measurement , 1979 .

[4]  Pietro Lura,et al.  Autogenous Deformation and Internal Curing of Concrete , 2003 .

[5]  Bhushan Lal Karihaloo,et al.  High performance fibre-reinforced cementitious composite (CARDIFRC) - Performance and application to retrofitting , 2007 .

[6]  Tommy Nantung,et al.  Volume change and cracking in internally cured mixtures made with saturated lightweight aggregate under sealed and unsealed conditions , 2009 .

[7]  K. A. Snyder,et al.  A Numerical Test of Air Void Spacing Equations , 1998 .

[8]  A. Loukili,et al.  Hydration kinetics, change of relative humidity, and autogenous shrinkage of ultra-high-strength concrete , 1999 .

[9]  S. Torquato,et al.  Nearest-surface distribution functions for polydispersed particle systems. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[10]  Emmanuel K. Attiogbe,et al.  MEAN SPACING OF AIR VOIDS IN HARDENED CONCRETE , 1993 .

[11]  M. Pigeon,et al.  The Use of the Flow Length Concept to Assess the Efficiency of Air Entrainment with Regards to Frost Durability: Part I—Description of the Test Method , 1996 .

[12]  Mehmet Ali Tasdemir,et al.  Optimisation of using lightweight aggregates in mitigating autogenous deformation of concrete , 2009 .

[13]  T. Powers,et al.  THE AIR REQUIREMENT OF FROST RESISTANT CONCRETE , 1950 .