7 Oct 2024

Full-Scale Evaluation of Saltwater Concrete for Airfield Pavement Construction and Repair

Abstract: The US Navy has a need to rapidly construct concrete facilities onshore to support contingency operations. Mixing water for concrete is typically specified to be freshwater; however, in many scenarios there are limited amounts of freshwater available for construction. Thus, use of readily available saltwater would be advantageous. This project’s objective was to evaluate the suitability of saltwater as a replacement for freshwater for producing concrete airfield pavement under relevant operational scenarios. Three full-scale test sections were constructed, and performance was evaluated in the context of relatively short design life requirements. First, direct comparison slabs of freshwater and saltwater concrete were constructed and exposed to ambient environmental conditions for one year; periodic concrete strength measurements were made. Next, 8 in. thick and 11 in. thick saltwater concrete pavements were constructed then subjected to P-8 aircraft accelerated loading. Finally, four airfield damage repair techniques were executed using saltwater and subjected to accelerated P-8 aircraft loading. Saltwater concrete performance was found to be similar to freshwater concrete for all scenarios investigated. The overall conclusion was that saltwater can be used in place of freshwater for concrete airfield pavement construction and repair for short- to medium-term use (1–2 yr) with no meaningful impact to mission requirements.

25 Sep 2024

Accelerated Concrete Flexural Strengths for Airfield Pavements

Abstract: Mixture-proportioning studies and submittals are an integral part of the pavement design and planning process as outlined in the Unified Facilities Guide Specification 32 13 14.13 for Department of Defense airfield pavements. Many aspects of the required testing are time-consuming due to the duration of the test (e.g., alkali–silica reaction experiments) or to the required concrete age at testing (e.g., compressive or flexural strength testing). Time awaiting testing results often delays projects and adds cost. The objective was to develop an accelerated testing requirement for flexural strength (currently 650 psi or greater at 90 days), thereby reducing the time to pavement acceptance. Potential accelerated testing methodologies were evaluated in a literature review. A statistical analysis generated under a design of experiments protocol determined concrete flexural strength gain and correlation ratios. Results of the statistical analysis showed that a reduced flexural strength of 600 psi could be accepted at 14 days and still reach the minimum flexural strength requirement of 650 psi at 90 days with high certainty (i.e., greater than 95% certainty). Additionally, the results stemming from the design of experiments compared favorably with data gathered from four mixture-proportioning submittals acquired via the Transportation Systems Center.

17 May 2024

Additive Regulated Concrete for Thermally Extreme Conditions

Abstract: This study details a multiprong effort to validate the Cold Regions Research and Engineering Laboratory’s solution for concrete construction and repair in cold weather, Additive Regulated Concrete for Thermally Extreme Conditions (ARCTEC). ARCTEC is the product of several years of research and consists of a testing and simulation workflow which generates scenario-sensitive guidance for use of accelerating admixtures in concrete. This report details efforts to validate ARCTEC using real-world, full-scale, field demonstrations. These demonstrations were used to collect data on the behavior of concrete obtained through conventional supply chains, to assess the accuracy of the simulation component of the workflow, and test efficacy of ARCTEC guidance in achieving frost protection. Results indicate that ARCTEC is at a high level of maturity, and provides additive dosage guidance that ensures frost protection and strength development in concrete placed where overnight lows fall as low as 0°F. The effort and cost required to implement ARCTEC as a cold weather protection strategy is minimal, and significantly less burdensome than conventional methods. Any cold region installation with a winter construction or repair needs and access to conventional concrete supply chains could field ARCTEC, and reduce the cost and schedule constraints associated with winter construction.

27 May 2021

Long-term performance of sustainable pavements using ternary blended concrete with recycled aggregates

Abstract: Dwindling supplies of natural concrete aggregates, the cost of landfilling construction waste, and interest in sustainable design have increased the demand for recycled concrete aggregates (RCA) in new portland cement concrete mixtures. RCA repurposes waste material to provide useful ingredients for new construction applications. However, RCA can reduce the performance of the concrete. This study investigated the effectiveness of ternary blended binders, mixtures containing portland cement and two different supplementary cementitious materials, at mitigating performance losses of concrete mixtures with RCA materials. Concrete mixtures with different ternary binder combinations were batched with four recycled concrete aggregate materials. For the materials used, the study found that a blend of portland cement, Class C fly ash, and blast furnace slag produced the highest strength of ternary binder. At 50% replacement of virgin aggregates and ternary blended binder, some specimens showed comparable mechanical performance to a control mix of only portland cement as a binder and no RCA substitution. This study demonstrates that even at 50% RCA replacement, using the appropriate ternary binder can create a concrete mixture that performs similarly to a plain portland cement concrete without RCA, with the added benefit of being environmentally beneficial.

30 Apr 2020

PUBLICATION NOTICE: Effects of Boric Acid and Water Content on Fundamental Properties of Proprietary Magnesium Phosphate Cement (MPC) Products

Abstract: Magnesium phosphate cements (MPCs) have been used for decades in proprietary products for pavement repairs. However, products with high exothermic temperatures have short working times, and research is needed to overcome these unfavorable characteristics. The effects of different boric acid and water contents on the fundamental properties of concrete was investigated through 34 trial batch modifications on the following commercially available MPC products: (1) Premier Magnesia’s PREMag PGDM, (2) BASF Master Builder’s MasterEmaco T545, and (3) CeraTech Inc.’s Pavemend TR. Overall results indicated that the increase of boric acid and water content produced favorable decreased temperatures and increased set times but retardation in the early age development of compressive strength. Modifications in the PREMag PGDM product resulted in poor workability, inaccurate time of setting due to a thixotropic nature, and unacceptable compressive strength loss. The Pavemend TR product was significantly affected by the addition of boric acid resulting in nonrecoverable compressive and bond strength loss, excessive expansions, failure at low freezing and thawing cycles, and unacceptable times of setting for rapid-repair applications. The T545 product showed promising performance with 28-day recovery in compressive, flexural, and bond strengths and minimal differences in other properties when compared to the control mixture.

7 Apr 2020

PUBLICATION NOTICE: Development of Magnesium Phosphate Cement (MPC) Concrete Mixture Proportioning for Airfield Pavements: Laboratory and Field Validation MPC Test Report

 Link: http://dx.doi.org/10.21079/11681/35475Report Number: ERDC/GSL TR-20-4Title: Development of Magnesium Phosphate Cement (MPC) Concrete Mixture Proportioning for Airfield Pavements:Laboratory and Field Validation MPC Test ReportBy Monica A. Ramsey, Dylan A. Scott, Charles A. Weiss Jr., and Jeb S. TingleApproved for Public Release; Distribution