Performance of carbonated calcium silicate based cement pastes and mortars exposed to NaCl and MgCl2 deicing salt

Article · May 2016with389 Reads
DOI: 10.1016/j.conbuildmat.2016.02.098
Abstract
This paper investigates the performance of two cementitious systems exposed to freezing or deicing salts. The first cementitious system is made using an ordinary portland cement (OPC) that reacts through hydration. The second cementitious system is made using a calcium silicate cement (CSC) that reacts and gains strength through carbonation (i.e., carbonated calcium silicate based cement (CCSC)). Two experimental techniques were used to evaluate the performance of these materials. The first technique measures the potential reactivity between the concrete paste and the deicing salt (NaCl and MgCl2) using a low temperature differential scanning calorimeter. The second technique uses a longitudinal guarded comparative calorimeter equipped with acoustic emission to assess the freeze–thaw performance of mortar samples saturated with water or deicing solutions. No chemical reaction is observed between CCSC paste and NaCl while a damaging reaction is observed between the OPC paste and NaCl due to the presence of calcium sulfoaluminate phases. A chemical reaction occurs for both the CCSC and OPC paste exposed to MgCl2: for the CCSC paste, this appears non-deleterious since relatively no reduction in dynamic elastic modulus is observed; for OPC paste, however, this is a damaging reaction due to formations of magnesium silicate hydrate and calcium/magnesium oxychloride. CCSC mortar sample saturated with water shows freezing in the large pores at approximately −5 °C and smaller pores at approximately −28 °C. Both the OPC and CCSC mortars show similar freeze–thaw performance when the system is water saturated. When the water in the pores of the mortar is replaced with a salt solution (NaCl and MgCl2), the CCSC mortar shows less freeze–thaw damage (mainly due to possessing a different pore structure) and more resistance to salt degradation (mainly due to possessing a different chemistry) than the OPC mortar does.
Project
The current level of construction activity provides INDOT with the opportunity to collect information from concrete paving projects which can be used to generate information that may be used to imp…" [more]
Project
The focus of this study is to improve the performance and predictability of patching materials with high early strength and long term durability. By improving the predictability and performance of …" [more]
Project
This project examines the use restrained specimens for determining the potential for restrained shrinkage cracking in concrete. The project describes: 1) A dual ring test that shortens the testin…" [more]
Article
June 2015 · Advances in Civil Engineering
    The chemical interaction between calcium chloride (CaCl2) and cementitious binder may alter the transport properties of concrete which are important in predicting the service life of infrastructure elements. This paper presents a series of fluid and gas transport measurements made on cementitious mortars before and after exposure to various solutions with concentrations ranging from 0% to... [Show full abstract]
    Article
    November 2015 · Transportation Research Record Journal of the Transportation Research Board · Impact Factor: 0.54
      The behavior of two cementitious materials during thermal changes associated with freezing and thawing in presence of calcium chloride deicing salts was examined. The two systems consisted of a conventional portland cement-based material and an alternative economically friendly cement that formed a solid by carbonating a calcium silicate–based cement. Low-temperature differential scanning... [Show full abstract]
      Conference Paper
      June 2015
        In North America, some concrete pavements and sidewalks have shown severe damage during freezing. The damage may increase as deicing salts (e.g. NaCl) are added to the surface of pavement in order to melt ice and snow due to the addition of osmotic/crystallization pressure or/and chemical reaction. Research has been performed to better understand the cause of damage. A test device (called... [Show full abstract]
        Article
        September 2015 · Construction and Building Materials · Impact Factor: 2.30
          Magnesium chloride (MgCl2) is used in deicing applications due to its capability to depress freezing temperatures to a lower point than other salts such as sodium chloride (NaCl). The constituents of concrete (i.e., pores solution, calcium hydroxide, aluminate phases, and calcium silicate hydrate gel) can alter the MgCl2–H2O phase diagram when it is used to interpret the performance of... [Show full abstract]
          Discover more