Roller-compacted Concrete Mix Research Articles

Compaction Delay and Temperature Effects on Early-Age Properties of Roller-Compacted Concrete

The lower water content of roller-compacted concrete (RCC) coupled with climatic conditions (e.g., higher air temperature, increased wind speed, and lower relative humidity) and compaction delay factors (e.g., traffic delay, plant location, and paving speed) can significantly affect the in situ density and hardened properties of RCC pavements. In this study, a control RCC mix was batched and maintained at standard (21°C) and elevated (35°C) temperatures and then compacted at increasing delay times for up to 180 min. The elevated mix temperature and compaction delay times greater than 90 min prevented the RCC mix from achieving 98% of the initial wet density from the modified Proctor test. Two additional RCC mixes were batched to determine if they could maintain a longer compaction window, one containing a rheology-modifying and retarding admixture and the other incorporating saturated fine lightweight aggregates. The RCC with admixture was the most effective at maintaining moisture content, density, compressive strength, and fracture properties at all compaction delay times. For example, at 180 min of delay, the RCC mixture with admixture still maintained 98.2% of the initial wet density, 81% of the compressive strength, and approximately the same fracture toughness and energy. The addition of fine lightweight aggregates did not extend the compaction window relative to standard RCC mix. The gyratory compacted specimens were more sensitive to the effects of temperature and compaction delay on RCC mixes than the vibratory hammer prepared specimens.

Role of Additives in Compacted Concrete Pavements

Roller compacted concrete (RCC) is an emerging pavement technology especially for secondary roads and is additionally valued for its lower installation costs, faster opening to traffic, high load-carrying capacity, and durability. One major drawback to use of RCC in secondary roads is the balance of smoothness and target surface durability over time. To achieve more consistent RCC mixes, the compaction (flow) performance and rheology of about 40 freshly prepared zero-slump graded aggregate concrete pastes were explored with selected types and levels of additives and water saturation levels. Viscosity modifiers were found to be critical to achieve the highest yield strength formulations. The high yield strength RCC formulations identified from this study followed the key guidance, namely graded aggregate, viscosity, and lubricity, of the Superpave program for fresh asphalt concrete.

Estimating the compressive strength of roller compacted concrete using a novel swarm-optimised light gradient boosting machine

ABSTRACT This study proposes a data-driven method for predicting the compressive strength (CS) of roller-compacted concrete (RCC). The new method is an integration of light gradient boosting machine (LightGBM) and particle swarm optimization (PSO). The former is used to generalize the mapping relationship between the CS and its influencing factors. The latter is employed to optimize the learning phase of LightGBM. A dataset, consisting of 408 laboratory tests and eight predictor variables, has been collected from the literature to train and verify the proposed data-driven method. Experimental results, supported by statistical hypothesis tests, point out that the proposed approach achieves outstanding performance with a root mean squared error of 4.53 and a mean absolute percentage error of 13.2%. The new model, named PSO-LightGBM, is capable of explaining roughly 90% of the variation in the CS of RCC mixes. In addition, an asymmetric loss function is applied in the training phase of LightGBM to reduce the proportion of overestimated CS values from 53% to 32%. This reduction in overestimations can help enhance the reliability of the data-driven method. Therefore, the newly developed model can serve as a decision-supporting tool in designing RCC mixtures.

Risk-Informed Design of RCC Dams under Extreme Seismic Loading

The existing Scoggins Dam and reservoir are in Washington County, Oregon, and the title is held by the U.S. Bureau of Reclamation (Reclamation). Reclamation has previously identified dam safety concerns related to the existing embankment dam. Regional project sponsors, including Clean Water Services, have identified the need for expanded storage capacity in the reservoir to meet growing water demands and address water quality issues in the Tualatin River downstream of the dam. As part of efforts to resolve dam safety issues and increase the water storage in the reservoir, a comprehensive feasibility level design of a new 185-foot-high Roller Compacted Concrete (RCC) dam. Extraordinary seismic hazards have been identified in the region associated with the Cascadia Subduction Zone (CSZ). Further, any dam alternative carried forward for funding, final design, and construction will have to meet the Public Protection Guidelines (PPG) of Reclamation that require a formal quantitative risk analysis. A risk-informed design approach was adopted to configure the layout and cross-section properties of the dam. A multi-phase site characterization program and preliminary RCC mix design program were performed to support the design. In addition, models were developed, and an extensive suite of both (two-dimensional) 2D and (three-dimensional) 3D structural analyses were performed for seismic loadings with total durations of over 200 s, strong shaking of over 140 s, and peak ground accelerations of over 2 gravitational accelerations (g) (up to 50,000-year return period event). This paper describes the feasibility design configuration of the dam, including the seismic hazard characterization, structural analysis models, and seismic response modeling results. The expected performance of the dam relative to the risk-informed design criteria and Reclamation PPGs will be generally described.

Study on effect of fly ash and limestone powder on compressive strength of roller compacted concrete for dam construction

Roller compacted concrete (RCC) is a special concrete having similar ingredients as in the case of conventional concrete, but in different proportions. Use of fly ash to replace significant proportion of Portland cement (PC) for RCC mix is very popular. However, use of limestone in RCC is not so popular. Limestone can act as an inert filler as well as can take part in hydration process and development of different hydration products to a limited extent. The study attempts to determine the optimal replacement levels of PC using fly ash and limestone for development of high volume fly ash based roller compact concrete with limestone filler for use in construction of dams in India by evaluating the fresh properties (in terms of Vee Bee time, density and setting time) and compressive strength (at 7, 28, 56, 90 and 180 days) for different RCC mixes having varying proportions of PC, fly ash and limestone. The study evaluation of 17 RCC mixes prepared by replacing PC to an extent of 72% (by weight of total cementitious content) using two types of fly ash and two types of limestone from different sources to observe the variations in setting time, short and long-term strength for the concrete. For RCC mixes having ternary cementitious systems (combination of OPC, fly ash and limestone), setting time values were observed to be in between setting times of mixes made with binary cementitious systems (i.e. OPC and limestone & OPC and fly ash). Optimum performance in terms of compressive strength at all the ages was observed for mixes with ternary cementitious system due to the synergistic contributions (physical and chemical) of both fly ash and limestone.

Seepage Mitigation in Hydropower Dams by Optimization in Roller Compacted Concrete Interlayer (Monoliths) Joint Bonding Technology

Roller Compacted Concrete (RCC) has gained favorable recognition in hydropower and water resource dam construction. With optimization in construction technology and materials used for RCC Dams, cost is no longer a major disadvantage as compared to environmental impact, that is, wildlife habitat disruption. In as much as it has become optimal for investment in hydropower dam construction, the scourge for dam failure is still eminent, which is as a result of excessive seepage compromising the integrity of the mechanical properties of the dam. The aim of the paper is to highlight successful application methods in joint bonding to avoid excessive seepage and reduce the autogenous healing to a few years of operation. In view of optimization, this paper presents a comprehensive study on the influences of interlayer joints bonding quality from RCC mix performances and how it consolidates the RCC layers to withstand the shear strength along the interface, especially on the high dams. The case study is the RCC dam at the 750 MW Kafue Gorge Lower Hydropower Station. The scope of the study reviews the joint type judged by Modified Maturity Factor (MMF) with joint surface long time exposed in regions with dry and high temperature, technical measures of layer bonding quality control under condition of long time joint surface exposure, effects of joints shear strength and impermeability of the RCC layers when under the conditions of plastic and elasticity. The subtle observations made during the dam construction phases were with respect to the optimal use of materials in relation to RCC mix designs and the basis for equipment calibration for monitoring important data that can be referenced during analysis of shear forces acting on the RCC dam over time.

Modelling compactibility of RCC specimens using the asphalt gyratory compactor

The density of fresh Roller Compacted Concrete (RCC) pavement dictates its durability and mechanical characteristics. Achieving the required density depends on many factors but mainly on the thickness of the lift and the RCC mix constituents. To evaluate the compactibility of fresh RCC mixes prior to placement, current practices recommend using no-slump consistency tests such as the Vebe test. However, these tests lack sensitivity to the dryness of RCC mixes as well as to the placement thickness. This paper proposes an approach to evaluate the compacatibility of RCC specimens by estimating the energy required to achieve the specified density over the thickness of different mixes. In order to study the energy, the Superpave Gyratory Compactor (SGC) was incorporated as a consistent and accurate compaction tool. The SGC provides displacement records with gyration numbers that facilitate i) density calculations through volume change and, ii) model, the compactibility of RCC, mixes using vibrational mechanics. A damping coefficient and a time-dependent restoring force were estimated and used to calculate the mechanical energy at each gyration and the cumulative energy after 25 gyrations. The damping coefficient, which is a material property, was further used to determine the cumulative energy of different RCC thicknesses. This approach investigated the effect of the specified lower and upper aggregate gradation and the use of additives on compactibility and density of RCC mixes.

A new evaluation of the fatigue design criteria of roller compacted concrete (RCC) pavements

Although mechanical fatigue loading can generally cause critical stresses in pavement systems, there have been few studies that specifically investigate fatigue behavior of roller-compacted concrete (RCC). Possible reasons for this lack include the complexity and time-consuming nature of fatigue tests as well as difficulties in producing RCC prismatic specimens because of stiff consistency in their fresh state. In this experimental study, to simulate actual field-compaction procedures, three RCC mixes of different performance categories were compacted in a plate mold by first applying a vibratory plate compactor, followed by a small-scale vibratory hand roller. Fatigue behavior of RCC mixtures was investigated by applying fatigue loads at five different stress ratios on beam specimens taken from the compacted plates. The average fatigue strength of RCC corresponding to 2 million loading cycles was found to be about 62.5% of the ultimate static strength, showing that RCC performs better than conventional concrete under fatigue. Using a Weibull distribution, the failure probabilities of these mixtures were also determined and expressed as an S-N-P curve. The relationships between RCC fatigue life and mixture design parameters showed that the degree of compaction of a specimen significantly affects the fatigue performance of RCC. A fatigue-life model considering the mixture parameters was also developed, providing a more realistic and novel solution than other RCC fatigue life-estimation models found in the literature that consider only stress ratios. This model is less conservative than those currently used in pavement design.

The Feasibility of Using Micro Silica Sand Powder as Partial Replacement of Cement in Production of Roller Compacted Concrete

Roller compacted concrete (RCC) is a special type of concrete with zero or even negative slump consistency. In this work, it had aimed to produce an RCC mix suitable for roads paving with minimum cost and better engineering properties so, different RCC mixes had prepared i.e. (M1, M2, M3, and M4) using specified percentages of micro natural silica sand powder (SSP) as partial replacement of (0%, 5%, 10%, and 20%) by weight of sulfate resistant Portland cement. Additionally, M-sand, crushed stone, filler, and water had been used. The results had obtained after 28 days of water curing. The control mix (M1) had satisfied the requiredf ‘cwith accepted results for the other tests. M2 mix with SSP of 5% had achieved the highest results. Thef ’cfor sawed cubes of (10*10*10) cm had increased by 2.26% and 3.16% when tested in directions (ꓕ and //) to the direction of loading respectively.Rresults for sawed prisms of (38*10*10) cm had increased by 8.78% and 8.43% when tested on top and bottom faces respectively. The density had increased by 1.04% while the absorption and volume of permeable voids had decreased by 8.11% and 7.83% respectively. The UPV results had also increased by 2.44% and 0.81% for cubes and prisms respectively when compared to the control mix. M3 mix with SSP of 10% had also achieved satisfactory results when compared to the control mix.

Some Properties of RCC Containing Silica Sand Powder Exposed to MgSo4 Solution

Roller compacted concrete (RCC) is a special type of concrete with zero or even negative slump consistency. This work has been targeted to produce and investigate the durability of an RCC mix suitable for roads paving with better engineering properties. Different RCC mixes have been prepared using micro natural silica sand powder (SSP) as a partial substitution by weight of sulfate resistant Portland cement, i.e., [0% (M-R), 5% (M-SSP5), 10% (M-SSP10), and 20% (M-SSP20)]. Additionally, M-sand, crushed stone (NMSA of 19.0 mm), filler, and water were used. Materials have been proportioned according to ASTM D1557. Slabs prepared and cast in molds with dimensions of 38×38×10cm using a vibrating table and manually operated human-made rolling device. Sawing was made after 28 days of normal curing to obtain cubes of 10×10×10cm and prisms of 10×10×38cm used for different tests. Continuous full immersion in 5% MgSO4 solution at a temperature of (23±2)°C for 60 and 120 days was implemented to investigate the durability of RCC specimens. The compressive strength (f’cu) of M-SSP5 increased by 7.35% and 7.14%, and the flexural strength (fr) increased by 32.1% and 33.67%, after 60 and 120 days of exposure, respectively, compared to the control mix.

Effect of Ground Granulated Blast Furnace Slag (GGBFS) on Mechanical Properties of Roller-Compacted Concrete Pavement

Abstract Because of various convenient features, such as high manufacturing speed, cost effectiveness, and high strength at low ages, roller-compacted concrete (RCC) has found growing use in the construction of concrete pavements. This study investigated the effect of ground granulated blast furnace slag on the mechanical properties (compressive and tensile strength and modulus of rupture) of RCC at the ages of 28 and 90 days. For this purpose, 40 preliminary RCC mix designs based on slag contents of 0, 20, 40, and 60 % (by weight of cementitious materials), moisture contents of 4, 4.75, 5.5, 6.25 and 7 % (by total weight of cementitious materials and aggregates), and cementitious material contents of 12 and 15 % (by weight of aggregate) were devised and tested to determine the optimum moisture content for eight primary mix designs. The primary mix designs were used to make 144 specimens for the evaluation of targeted mechanical properties. The results showed that the moisture content that was needed to reach maximum compaction increased with increasing slag content. The highest strengths were observed in the specimens that contained 40 % slag, which all exhibited equal or greater strength than the corresponding slag-free specimens. The scanning electron microscope images showed that this difference can be attributed to the better filling of pores and cracks with small-sized slag particles, which outperform cement particles in this respect. It seems that there is an optimum level for replacing cement with slag in order to achieve improved strength and that exceeding this level will lead to strength reduction. In this study, this optimum level was found to be 40 % slag. Moreover, increasing the cementitious material content from 12 to 15 % was found to increase the compressive strength, tensile strength, and modulus of rupture by reducing the water-to-cement ratio.

Mechanical and durability behaviour of roller-compacted concrete containing white cement by pass dust and polypropylene fibre

This research investigates the potential use of waste white cement by pass dust (WCBPD) in producing roller-compacted concrete (RCC). Fifteen RCC mixes were casted in which cement was partially replaced by WCBPD at (10, 20, 30 and 40%) with addition of polypropylene fibre in two percents (0.25 and 0.5%). The mechanical properties of RCC mixes were evaluated using compressive and splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity. The durability behaviour was evaluated through water absorption, dynamic modulus of elasticity and freeze–thaw resistant. Test results have shown that Increasing WCBPD to 20, 30 and 40% repalcement of cement has degraded the mechanical properties of RCC mixes. Even though, all RCC mixes reached a compressive strength greater than 27.6 MPa except mix with 40% WCBPD replacement level. All RCC mixes have shown a satisfactory durability. The addition of PPF has improved the mechanical and durability properties of RCC mixes with WCBPD. It is recommended to use waste WCBPD in producing RCC for up to 30% as a main base layer. Using WCBPD (as a replacement of cement) in producing RCC will effectively reduce the production cost and reduce environmental pollution by decreasing the disposal of this waste material in landfills.

Experimental testing and modelling of roller compacted concrete incorporating RAP waste as aggregates

In recent years, recycling reclaimed asphalt pavement (RAP) has been growing to resolve the waste storage problem and to limit usage of natural resources. One possible recycling technique is cold reuse of RAP as an alternative aggregate in manufacturing roller compacted concrete (RCC) which is an innovative technique for sustainable pavements. The objectives of this study are twofold. Firstly, the effects of substitution of natural aggregates by RAP on RCC mechanical properties (modulus of elasticity, splitting-tensile strength and compressive strength) are tested experimentally. Then, several existing compressive strength models (Bolomey, Tango, and de Larrard models), initially developed for ordinary Portland cement concrete, were tested to evaluate their relevance to the case of this particular concrete. Mechanical laboratory tests results carried on six designed RCC mixes showed that the RCC properties decrease as RAP content increases. Besides, compressive strength modelling results showed that the tested models are all relevant, to different degrees, for the case of the studied mixtures. de Larrard model which accounts for the adhesion quality between aggregate and cement matrix showed that this region is negatively affected by RAP presence. This finding can explain the observed decrease in the mechanical characteristics.

Abrasion Resistance and Mechanical Properties of Waste-Glass-Fiber-Reinforced Roller-compacted Concrete

The potential use of waste glass fibers in roller-compacted concrete (RCC) was investigated with the aim to improve its performance and reduce environmental effects. The research was focused on the abrasion resistance and compressive and flexural strengths of the reinforced concrete relative to those of reference mixes without fibers. The freeze-thaw resistance of RCC mixes was also examined. It was found that the use of waste glass fibers at a rate of 2 % increased the abrasion resistance of the RCC mixes considerably.

Mechanical properties and performance of high volume fly ash roller compacted concrete containing crumb rubber and nano silica

This study deals with the development of an environmentally sustainable roller-compacted concrete (RCC) using high-volume fly ash (HVFA) and crumb rubber as partial replacement for cement and fine aggregate respectively, and nano-silica as an additive to cementitious materials. Response surface methodology (RSM) was used to design, develop statistical models, and carry out the optimization for the mixtures using the variables crumb rubber, HVFA, and nano-silica. The responses used for the RSM are compressive, flexural, and splitting tensile strengths. The proposed models demonstrated a high correlation among the variables and responses. An optimised HVFA RCC mix can be achieved by partially replacing 10% fine aggregate with crumb rubber by volume, replacing 53.72% of cement with fly ash by volume, and the addition of 1.22% nano-silica by weight of cementitious materials. Further experimental investigations showed that the HVFA RCC pavement exhibited lower fresh density, Vebe time, compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, abrasion resistance, and impact resistance compared to conventional (control) RCC pavement. These effects further escalate with increase in partial replacement of fine aggregate with crumb rubber. On the other hand, nano-silica increases the mechanical properties and performance of HVFA RCC pavement with or without crumb rubber. This is because of the ability of nano-silica to partially mitigate the negative effect of crumb rubber on the properties of HVFA RCC by densifying the interfacial transition zone between the cement matrix and crumb rubber and filling the pores in the hardened cement matrix. Furthermore, nano-silica partially ignited the pozzolanic reactivity of fly ash at early ages which leads to higher performance of HVFA RCC pavement at early age.

Structural Design and Economic Evaluation of Roller Compacted Concrete Pavement with Recycled Aggregates

Using recycled aggregates in the concrete offers advantages in many areas such as waste management, energy save and natural resources, conservation of ecological balance, low CO2 emissions, and users are encouraged in this regard to use these materials. In this study, the profit / loss account arising in the structural design phase was investigated when Reclaimed Asphalt Pavement (RAP), which is limited to use in Roller Compacted Concrete (RCC) pavements, was used as coarse aggregate. RAP materials were used as coarse aggregates by the levels of 0%, 15% and 20% and mechanical properties such as compressive strength, flexural strength, splitting tensile strength and modulus of elasticity were investigated. In the last stage, the mechanical properties obtained from these experimental studies were entered into KENSLABS software as input, and the slab layer thicknesses were determined according to three different subgrade conditions and a certain fatigue criterion. According to the results, it has been determined that the use of RAP at a level of 20% is a serious reducing effect on mechanical properties and and the use of RAP at a level of 15% does not bring a great economic benefit but it is reasonable to use it as coarse aggregate in RCC mixes in consideration of environmental effects.

Mechanical properties of roller-compacted concrete with macro-fibers

The addition of macro-fibers to concrete slabs on ground have been shown to increase flexural capacity, fatigue resistance, reduce crack deterioration rates, and assist in shear transfer across joints and cracks. A laboratory study was performed to determine the benefits of macro-fibers in roller-compacted concrete (RCC) for pavements by measuring the change in RCCs mechanical properties and comparing it to conventional fiber-reinforced concrete for pavements. Six fiber types, four synthetic and two steel, with several fiber geometries were incorporated into RCC mixtures at two dosage levels (0.2% and 0.4% by volume). The addition of synthetic macro-fibers increased the maximum dry density (MDD) over the control RCC mix by reducing the internal friction between aggregates whereas steel fiber had a limited impact on the MDD of RCC. For several fiber types, the resultant RCC with fibers had a statistically significant increase in compressive and split tensile strength relative to the control RCC mix. The addition of fibers did not increase the flexural strength of RCC but did noticeably improve the post-peak and residual strength capacity of RCC. The increases in residual strength were dependent on the fiber type and geometry, similar to the behavior in conventional Portland cement concrete (PCC). The fracture properties of RCC with fibers based on disk-shaped compact tension (DCT) tests were shown to be similar or greater than PCC with fibers which indicates both RCC and PCC pavements, when properly constructed, will have similar fracture and fatigue resistance.

Experimental Verification of Properties of Roller-Compacted Concrete for Pavements

Increased requirements on environmentally friendly construction process of road structures with emphasis on economical savings and durability of roadways lead to search for new material solutions for pavements. Roller-compacted concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for placement of asphalt pavement layers. Its main advantage is relatively good ratio between mechanical properties and overall costs during construction, operation and maintenance phases. After extensive literature review on the use of RCC in the world, the authors focused themselves on a series of tests of specimens made from RCC mix to verify the main characteristics of the material. Slump, compressive and flexural strength, resistance of concrete to deicing chemicals and resistance to abrasion was tested. The results were assessed from the point of view of exploitation of RCC in pavement structures.

Mechanical properties of roller compacted concrete containing rice husk ash with original and recycled asphalt pavement material

This study focused on the effects of rice husk ash (RHA) on the mechanical properties of roller compacted concrete (RCC) designed with original and reclaimed asphalt pavement (RAP) materials. The RCC mixes were produced by partial substitution of cement with RHA at varying amounts of 3% and 5%. Four aggregate combinations including the mix with original aggregate, coarse RAP+fine original aggregate, coarse original aggregate+fine RAP and total RAP were considered. The main experimental design consisted of the compressive strength and three points bending tests. Bending test was used to measure the modulus of rupture, material’s energy absorbency and analyse the fatigue response of RCC mixes. All tests were performed after 7, 28 and 120days curing except the fatigue test that performed on 120days specimens. Adding RHA resulted in higher optimum moisture content (OMC) and lower maximum dry density. Furthermore, adding RAP with different dimensions reduced the OMC and maximum dry density. The material’s flexibility improved upon replacing 3% cement by RHA. However, the energy absorbency reduced by increasing the RHA content to 5%. The fatigue life of RCC mixes containing RAP material was lower than the conventional one. Furthermore, replacing the coarse aggregate by RAP led to higher fatigue life than the fine aggregate. There was a strong relationship (R2>0.90) between the energy absorbency and fatigue response of RCC mixes. At higher stress ratios of 0.72, the mix with higher energy absorbency behaved better under repeated loadings. Besides, a reverse relationship was found between the fatigue life and material porosity. Adding 3% RHA reduced the porosity especially after 120days curing and improved the fatigue resistance. However, the addition of RHA to 5% resulted in higher porosities and lower fatigue lives.

Fracture Properties of Roller-Compacted Concrete with Virgin and Recycled Aggregates

Roller-compacted concrete (RCC) pavement has renewed interest among designers as a sustainable pavement option with the potential to lower total cement content, incorporate recycled aggregates, reduce road closure time, and decrease total project costs. One main design challenge is whether RCC can achieve the same performance life as conventional portland cement concrete (PCC) pavement with similar slab thickness. This research investigated the strength and fracture properties of RCC containing virgin aggregates and fractionated reclaimed asphalt pavement (FRAP) relative to conventional PCC to address this design challenge. The compressive and split tensile strengths of the RCC mixes showed similar strengths to the same constituents in PCC. RCC containing FRAP had lower strengths than did RCC with virgin aggregates. The critical stress intensity factor and the initial and total fracture energies were not statistically different between the RCC mixes containing virgin and FRAP aggregates. Overall, the RCC fracture properties were found to be significantly higher than those of conventional PCC. At lower stress ratios, RCC fatigue data from laboratory beam tests predict lower fatigue life relative to PCC; this result translates to a thicker RCC pavement. Large-scale testing has shown that the flexural capacity of PCC slabs is strongly related to the concrete fracture properties despite differences in beam flexural strength. Because these RCC fracture properties were shown to be higher than similar constituents used in conventional paving concrete, RCC designs could employ similar PCC fatigue curves for certain conditions, such as when the RCC fracture properties are equivalent to or greater than those of conventional PCC.