• Computers and Concrete
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• v.33 no.4
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• pp.445-469
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• 2024

The Federal Highway Administration (FHWA) has recommended the use of AASHTOWare Pavement Mechanistic-Empirical Design (PMED) software for Roller-Compacted Concrete (RCC) pavement design, but specific calibration for RCC is missing. This study investigates the software's capacity to predict the long-term performance of RCC roadways within the framework of conventional concrete pavement calibration. By reanalyzing existing RCC projects in several U.S. states: Colorado, Arkansas, South Carolina, Texas, and Illinois, the study highlights the need for specific calibration tailored to the unique characteristics of RCC. Field observations have emphasized occurrence of early distresses in RCC pavements, particularly transverse-cracking and joint-related issues. Despite data challenges, the AASHTOWare PMED software exhibits notable correlation between its long-term predictions and actual field performance in RCC roadways. This study stresses that RCC applications with insufficient joint spacing and thickness are prone to premature cracking. To enhance the accuracy of RCC pavement design, it is essential to discuss the inclusion of RCC as a dedicated rigid pavement option in AASHTOWare PMED. This becomes particularly crucial when the rising popularity of RCC roadways in the U.S. and Canada is considered. Such an inclusion would solidify RCC as a viable third option alongside Jointed Plain Concrete Pavements (JPCP) and Continuously Reinforced Concrete Pavements (CRCP) for design and deployment of rigid pavements. The research presents a roadmap for future calibration endeavors and advocates for the integration of RCC pavement as a distinct pavement type within the software. This approach holds promise for achieving more precise RCC pavement design and performance predictions.

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.45-52
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• 2017

PURPOSES : The main purpose of this study is to develop a high elastic modulus and low-shrinkage roller-compacted concrete base (RCCB) in order to prevent fatigue cracking and reflective cracking in the asphalt surface layer of composite pavement. Using a rigid base material with low shrinkage can be a solution to this problem. Moreover, a strong rigid base with high elastic modulus is able to shift the location of critical tensile strain from the bottom of the asphalt layer to the bottom of the rigid base layer, which can prevent fatigue cracking in the asphalt layer. METHODS : Sensitivity analysis of composite pavement via numerical methods is implemented to determine an appropriate range of elastic modulus of the rigid base that would eliminate fatigue cracking. Various asphalt thicknesses and elastic moduli of the rigid base are used in the analysis to study their respective influences on fatigue cracking. Low-shrinkage RCC mixture, as determined via laboratory testing with various amounts of a CSA expansion agent (0%, 7%, and 10%), is found to achieve an appropriate low-shrinkage level. Shrinkage of RCC is measured according to KS F 2424. RESULTS : This study shows that composite pavements comprising asphalt thicknesses of (h1) 2 in. with E2 > 19 GPa, 4 in. with E2 > 15 GPa, and 6 in. with E2 > 11 GPa are able to eliminate tensile strain in the asphalt layer, which is the cause of fatigue cracking in this layer. Shrinkage test results demonstrate that a 10% CSA RCC mixture can reduce shrinkage by 84% and 93% as compared to conventional RCC and PCC, respectively. CONCLUSIONS : According to the results of numerical analyses using various design inputs, composite pavements are shown to be able to eliminate fatigue cracking in composite pavement. Additionally, an RCC mixture with 10% CSA admixture is able to reduce or eliminate reflective cracking in asphalt surfaces as a result of the significant shrinkage reduction in the RCC base. Thus, this low-shrinkage base material can be used as an alternative solution to distresses in composite pavement.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.137-160
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• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• Advances in concrete construction
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• v.8 no.2
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• pp.127-137
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• 2019

Roller Compacted Concrete (RCC) is a zero slump concrete consisting of a mixture of cementitious materials, sand, dense graded aggregates and water. In this study, an attempt has been made to investigate the effect of aggregate type on strength and abrasion resistance of RCC made by using granulated blast furnace slag (GGBS) as partial replacement of cement. Mix proportions of RCC were finalized based upon the optimum water content achieved in compaction test. Two different series of RCC mixes were prepared with two different aggregates: crushed gravel and limestone aggregates. In both series, cement was partially replaced with GGBS at a replacement level of 20%, 40% and 60%. Strength Properties and abrasion resistance of the resultant mixes was investigated. Abrasion resistance becomes an essential parameter for understanding the acceptability of RCC for rigid pavements. Experimental results show that limestone aggregates, with optimum percentage of GGBS, perform better in compressive strength and abrasion resistance as compared to the use of crushed gravel aggregates. Observed results are further supported by stoichiometric analysis of the mixes by using basic stoichiometric equations for hydration of major cement compounds.

• Structural Engineering and Mechanics
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• v.40 no.2
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• pp.149-165
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• 2011

In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic $150{\times}150{\times}150$ mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using a soil-based compaction method and the optimum moisture content obtained from the pertaining experiments, and by adding different percentages of Iranian pozzolans as well as different amounts of steel fibers, each one accompanied by 0.1% of poly-propylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease, but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers, but neither steel nor PP fibers did contribute to increase in the rupture modulus independently. Also, the toughness indices increased when steel fibers were used.

• Structural Engineering and Mechanics
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• v.90 no.5
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• pp.467-480
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• 2024

The mechanical properties and durability of concrete pavements may be degraded in extreme situations, resulting in the need for partial repair or total replacement. During the past few decades, there has been a growing body of research on substituting a portion of Portland cement with alternative cementitious materials for improving concrete properties. In this study, two different configurations of powdered and granulated blast furnace slag were implemented, replacing fine aggregates (by 12 wt.%) and Portland cement (by 0, 20, 40, and 60 wt.%) in the making of roller-compacted concrete (RCC) mixes. The specimens were fabricated to investigate the mechanical properties and durability specifications, involving freeze-thaw, salt-scaling, and water absorption resistance. The experimental results indicated that the optimum mechanical properties of RCC mixes could be achieved when 20-40 wt.% of powdered slag was added to concrete mixes containing slag aggregates. Accordingly, the increases in compressive, tensile, and flexural strengths were 45, 50, and 28%, in comparison to the control specimen at the age of 90 days. Also, incorporating 60 wt.% of powdered slag gave rise to the optimum mix plan in terms of freeze-thaw resistance such that a negligible strength degradation was experienced after 300 cycles. In addition, the optimal moisture content of the proposed RCC mixtures was measured to be in the range of 5 to 6.56%. Furthermore, the partial addition of granulated slag was found to be more advantageous than using entirely natural sand in the improvement of the mechanical and durability characteristics of all mixture plans.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1117-1123
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• 2016

Roller-Compacted Concrete Pavement (RCCP) is a type of pavement that shares conventional concrete pavement material characteristics and asphalt pavement construction characteristics. Even though RCCP is compacted in the same way and have similar aggregate gradation to asphalt pavements, its materials and structural performance properties are similar to those of conventional concrete pavement. With cement hydration and aggregate interlock, Roller-Compacted Concrete or RCC can provide strength properties equal to those of conventional concrete with low cement content. Therefore, compaction ratio of RCC can highly influence on its strength. In general, 95% of compaction ratio is required for proper strength development. RCC strength can be highly influenced by compaction energy which depends on compaction equipment and compaction method. Therefore, it is necessary to analyze the relationship between compressive strength and compaction ratio of RCC. RCCP specimens were produced at different compaction ratio by using different compaction methods and energies. The compaction ratio was defined by the ratio of the specimen's dry density and its maximum dry density. The maximum dry density was obtained from Modified Proctor test. 28 days compressive strength corresponding to each compaction ratio case was tested. Finally, the relationship between compressive strength and compaction ratio can be analyzed. For application of roller-compacted concrete in domestic construction site, the relationship is important for field compaction management.