# Resistance of Concrete with Crystalline Hydrophilic Additives to Freeze-Thaw Cycles
###### Abstract  
The study explores the hypothesis that crystalline hydrophilic additives (CA) can enhance concrete's resistance to freeze/thaw cycles, crucial for assessing building durability. Employing EU standards, the research evaluates concrete resistance through standardized European freeze/thaw procedures. Monitoring concrete slabs exposed to freezing in the presence of deionized water and in the presence of 3% sodium chloride solution, the study measures surface damage and relative dynamic modulus of elasticity. Additionally, it assesses internal damage through monitoring of relative dynamic modulus of elasticity on cubes and prisms submerged in water and exposed to freezing/thawing. The pore spacing factor measured here aids in predicting concrete behavior in freeze/thaw conditions. Results suggest that the standard air-entraining agent offers effective protection against surface and internal damage due to freeze/thaw cycles. However, the CA displays potential in enhancing resistance to freeze/thaw cycles, primarily in reducing internal damage at a 1% cement weight dosage. Notably, a 3% replacement of cement with CA adversely affects concrete resistance, leading to increased surface and internal damage. The findings contribute to understanding materials that can bolster concrete durability against freeze-thaw cycles, crucial for ensuring the longevity of buildings and infrastructure. concrete; durability; crystalline hydrophilic additives; freeze-thaw cycles; surface damage; internal damage; pore spacing factor +
Footnote †: journal: Medical  
polycarbonate superplasticizers [20; 21], employing biomimetic polymer additives [22], and utilizing polymer fibers and biofilers [23; 24]. Crystalline admixtures (CA) are primarily commercially available products offered by various manufacturers (such as Xypex, Richmond, BC, Canada; Kryton, Vancouver, BC, Canada; Penetron, East Setauket, NY, USA; Harbin, China). They serve a dual function: reducing concrete permeability and repairing cracks [25]. The recommended dosage of CA in concrete typically ranges from 0.3% to 5% by the weight of the cement [26; 27]. Several authors have studied the impact of CA on the durability properties of concrete by monitoring crack healing, with most concluding its effectiveness in this regard [28; 29; 30; 31; 32]. It was noted that the highest rate of healing was observed when samples containing CA were consistently immersed in water [28; 29; 30]. According to [29; 33], calcium carbonate in the form of aragonite is formed in concrete cracks treated with CA, effectively sealing them. Considering the confirmed effectiveness of CA in the concrete crack healing process and the fact that cracks occur in concrete during freeze-thaw cycles, it would be intriguing to precisely determine the effectiveness of CA in enhancing concrete resistance to freeze-thaw cycles. European legislation mandates testing the resistance of concrete to freeze-thaw cycles through procedures outlined in standards CEN/TS 12390-9 [34] and CEN/TR 15177 [35]. In the method outlined in CEN/TS 12390-9 [34], concrete samples saturated with deionized water or a 3% sodium chloride solution undergo freeze/thaw cycles (56 cycles), during which surface scaling and mass loss of concrete are measured. The procedure described in CEN/TR 15177 [35] can be employed to monitor damage to the internal structure. Additionally, EN 480-11 [36] is used to predict concrete behavior under freeze-thaw conditions, involving microscopic observation of hardened concrete samples, measurement of pore spacing, and calculation of the pore spacing factor which is defined as distance of any point in cement paste to the edge of the nearest air void. Cement-based materials are considered resistant to freeze-thaw cycles if the spacing factor is less than 0.2 mm.