Pervious Concrete Chemical Degradation by Calcium Chloride Deicer
Liv Haselbach, Lamar UniversityShow Abstract
Nara Almeida, Lamar University
Molly Ross, Lamar University
The pervious concrete layer in a permeable pavement system may be susceptible to chemical degradation by various deicers applied during winter weather events. This research studied the chemical impacts of calcium chloride on pervious concrete specimens made in the laboratory and compared to specimens with a water only control. The 20 specimens were made with limestone aggregate and ordinary Portland cement (OPC) and were similar in porosity. 200 mL of deicer at a 3% mass concentration or water were poured onto the top of the 4-inch diameter specimens once weekly for 17 weeks and allowed to partially air dry in the laboratory in between applications. Debris started to fall from the bottoms of the specimens with the calcium chloride applications about halfway into the testing period. Unconfined compressive strength tests performed after the deicer applications were completed show a significant decrease in strength for the specimens which received the calcium chloride applications. It is recommended that calcium chloride deicers not be used on pervious concrete made with limestone aggregate and OPC.
An Approach to Characterize the Wearability of Concrete Pavement Surface Treatments
Carl Abou Sleiman, Texas A&M University, College StationShow Abstract
Xijun Shi, Texas A&M Transportation Institute
DAN ZOLLINGER, Texas A&M University
For a concrete pavement, the permeation specifications for the surface have a crucial influence on its durability. In this accelerated laboratory research, a surface treatment that combines lithium silicate chemistry with a reactive silicon catalyst was tested to typify the product longevity under traffic and against salt scaling. River gravel and limestone aggregates were used in two different mixture designs. Abrasion testing was conducted according to ASTM standards in which mass loss was recorded at different time intervals. A modification was employed using a diluted deicer simulated by 4 wt.% CaCl2 solution during 15 cycles of freeze/thaw testing. A model was proposed to relate the abrasion efficiency against load cycles of a treated surface to represent the longevity of a concrete pavement. Based on the abrasion coefficient and the texture wavelength of the pavement, it is shown that the life cycle under abrasion of a concrete pavement can be modeled. During the experimental procedures, the untreated concrete specimens were used as the control sample. Results from the abrasion and freeze/thaw testing of treated specimens indicated a lower level of cumulative loss damage, which confirms the benefits of using such products to extend the service life of a concrete pavement surface. The results of modeling indicated an increase of 14% of the ultimate load application to failure for the treated specimens, which indicates an increase in longevity of the pavement. Moreover, when exposed to freeze/thaw cycles, a limestone concrete showed less damage compared to the river gravel concrete mixture.
Assessing Freeze-Thaw Damage in SRW Units by Mass-Loss, Moisture-Gain, and Relative Dynamic Modulus
Ken Hover, Cornell UniversityShow Abstract
Cesar Tsz Chan, Cornell University
Segmental Retaining Walls (SRW’s) consisting of specialized units of concrete masonry have been used in many transportation-related highway applications, and their freeze-thaw durability is a key property, especially in the presence of deicing salts. Samples (coupons) cut from concrete masonry segmental retaining wall units were tested per ASTM C1262, using cumulative mass-loss to measure freeze-thaw damage. In addition to standard test protocols, wet and dry measurements of the mass of debris and residual coupons enabled continuous tracking of moisture content with freeze-thaw cycles. Damage was also assessed by Relative Dynamic Modulus (RDM) per ASTM C215, with particular attention to accommodate both the shape of SRW coupons, and the influence of moisture content on resonant frequency. It was necessary to correct the raw values of RDM to account for this moisture effect, and such correction is likewise applicable to ASTM C666 for ordinary concrete. It was demonstrated that mass-loss does not exclusively indicate surface-damage, and over a range of cycles mass-loss is proportional to RDM at a slope unique to each individual coupon. Mass-Gain (as moisture-absorption) during testing emerges as a key index to damage, with rapid escalation of mass loss and reduction in RDM at the number of freeze-thaw cycles required to increase coupon moisture content by about 1%. The findings reinforce fundamental research on the mechanism of freeze-thaw damage in concrete.
Laboratory Investigation of Foam Grout Performance Under Freeze and Thaw Conditioning
Vinicius Afonso Velasco Rios, University of AlbertaShow Abstract
Leila Hashemian, University of Alberta
Foam grout is a fluid, self-leveling and lightweight material with excellent load spreading and thermal insulation properties. These properties have contributed to foam grout being considered over its regular cement/water grout counterparts for many projects. Although applied in many successful cases, not much has been done to compare foam and regular grout behavior in cold regions. This research focused on the compressive strength of both materials before and after freeze/thaw cycles. Specimens were cured for different days in a moisture room and conditioned for diverse freezing/thawing cycles to assess short and long-term performance. The impact of immediate freezing was also evaluated for both materials. Foam grout’s ability to resist cold environments was explained using test results and visual analysis. At the end, a material cost versus strength analysis was conducted with the intent of providing a reliable source of information when selecting materials to fulfill minimum industry specifications.