Dimensional Stability of Grout-Type Materials Used as Connections between Prefabricated Concrete Elements Igor De la Varga 1 and Benjamin A. Graybeal, P.E., M.ASCE 2 Abstract: Prefabricated bridge elements and systems (PBES) construction relies on field-cast, grout-type materials to complete the connections between precast concrete elements. This PBES construction facilitates and accelerates bridge construction (ABC), increases safety, and min- imizes the inconveniences to the traveling public while delivering a superior product. Although prefabricated concrete components are produced in a controlled environment, field-cast grouts have at times shown serviceability issues mainly associated with dimensional stability. This paper assesses the dimensional stability (primarily shrinkage) of a total of seven prebagged grouts currently used in the construction industry. Their shrinkage performance is compared to that of an ultrahigh-performance concrete. The feasibility of the test methods used for evaluating the dimensional stability of nonshrink grouts is also discussed. Although many grouts are referred to as nonshrink materials, the results show shrinkage, especially in drying conditions. The use of the internal curing technology as an emerging solution for mitigating shrinkage in grout-type materials is also discussed. The results obtained in two of the cement-based grouts, including internal curing, show a reduction of both autogenous and drying shrinkage. Based on the results obtained, recommendations are given to end-users to provide guidance in selecting an appropriate grout-type material. DOI: 10.1061/(ASCE)MT.1943-5533.0001212. © 2014 American Society of Civil Engineers. Author keywords: Grout; Dimensional stability; Shrinkage; Bridge construction; Connections; Internal curing. Introduction and Research Objectives Grout-type materials are widely used in the construction industry for different applications such as joint sealing [G. J. Vanderlans, U.S. Patent No. 4,421,698 (1983), V. Weber, U.S. Patent No. 4,098,047 (1978), W. J. Clarke, U.S. Patent No. 4,318,835 (1982)], flooring [J. McIntosh and N. C. Sperling, U.S. Patent No. 7,543,417 (2009)], and structural repair (Shannag 2002; Khayat and Yahia 1998; Allen 1993), among others. In recent years, the use of grouts to connect precast concrete sections in bridges and other structures has become more prevalent (Culmo 2009). Grout is generally a mixture of cement, sand, water, and powder chemical admixtures. However, other types are also avail- able, such as epoxy-based, fly ash-based, and magnesium phos- phate-based grouts, to name just a few. They are normally proprietary materials that are prepackaged and ready to mix on site. One common use for grouts is in accelerated bridge construction (ABC) as connections between prefabricated bridge structural el- ements (an example is shown in Fig. 1). The use of prefabricated elements is one strategy that can meet the objectives of ABC. These structural components are built off-site and include features that reduce the on-site construction time and mobility impact time that occur with conventional construction methods. Because they are built off the critical path and produced under controlled environ- mental conditions, there are improvements in construction safety, product quality, and component long-term durability. Nonshrink cementitious grouts are most often used to easily and efficiently provide a connection between these precast concrete elements. Other types of grout may be acceptable for precast connections, but they are typically more expensive compared to cementitious grouts and may introduce the need for nonstandard considerations on the part of the designer. However, the field casting of the con- nections is a labor-intensive, critical part of making the overall sys- tem work successfully. This is why grout-type materials need to meet several high-level performance criteria, including high fluid- ity, relative impermeability, high early strength, corrosion protec- tion, sulfate resistance, and in some cases frost durability. Several research studies on the performance of grout-type ma- terials have been carried out in the last few decades (Culmo 2009; Gulyas et al. 1995; Issa et al. 2007; Ma 2010). However, the field- cast, grout-type materials specified for use in bridge connections have undergone limited research as to their relevance within this application. Graybeal et al. (2013) conducted extensive research in which the performance of different grout-type materials intended for use as bridge connections was evaluated. One of the outcomes of that research was the wide range of grout performance that can be obtained, as well as the propensity of the materials to undergo volumetric deformations (e.g., expansion and shrinkage). The pur- pose of the current study is to expand upon this work and inves- tigate the potential risk of shrinkage in grouts used as connections between prefabricated bridge structural concrete elements. The pa- per also addresses some of the issues behind the execution of some of the ASTM test methods used to evaluate volume changes in grouts. Although the use of grout-type materials as connections be- tween prefabricated concrete elements in bridges has been shown as a promising technique to facilitate ABC, the fact that they are designed with a low water-to-solids ratio (w=s) makes them prone to early-age shrinkage. “Nonshrink” grouts are covered under ASTM C1107 (“Standard Specification for Nonshrink Packaged Dry, Hydraulic-Cement Grout”)(ASTM 2014a); however, this standard lacks specificity in its definition of shrinkage limits. 1 Concrete Materials Engineer, SES Group & Associates, Turner- Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101 (corresponding author). E-mail: igor.delavarga.ctr@dot.gov 2 Team Leader, Bridge and Foundation Engineering Research, Federal Highway Administration, Turner-Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101. E-mail: benjamin.graybeal@ dot.gov Note. This manuscript was submitted on June 24, 2014; approved on October 3, 2014; published online on November 10, 2014. Discussion per- iod open until April 10, 2015; separate discussions must be submitted for individual papers. This paper is part of the Journal of Materials in Civil Engineering, © ASCE, ISSN 0899-1561/04014246(10)/$25.00. © ASCE 04014246-1 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by Federal Highway Administration on 11/14/14. Copyright ASCE. For personal use only; all rights reserved.