Predicting Mechanical Strength of Concrete Pavement: A Case Study with IoT-Based Monitoring Systems

Pavement strength is defined as the maximum stress that leads to crack initialization in a concrete pavement. Full-scale static step-loads were applied at the free edge of concrete slabs to induce bottom-up and top-down cracks, and then to determine the pavement strength. Both top- down and bottom-up crack initializations were successfully detected. Then the pavement strength was estimated using the collected test data and two assumptions: the pavement strength is similar at the slab top and bottom, and the residual stress at the slab top and bottom has the same magnitude but different signs. It has been found that the laboratory flexural strength of the cast beam was higher than the pavement strength in full-scale tests, while the flexural strength of the saw-cut beams from the slabs was lower than it.

ABSTRACTAirport pavements are designed to accommodate a broad range of aircraft loads, necessitating an airport-specific strength rating. Strength rating for a particular pavement is usually calculated deterministically, based on assumed pavement layer thicknesses and conservative values of stiffness for each layer of material. This research demonstrates a stochastic approach to flexible airport pavement strength determination via a case study on the Whitsunday Coast Airport. Construction records are statistically analysed and construction-based deterministic and stochastic strength ratings are compared to the design-based strength. The stochastic strength rating was generated by Monte Carlo simulation. The strength rating is found to vary greater with only slight differences in the probability of encountering understrength areas of pavement, and this case study is recommended as a template for the application to other airports. Also, 10,000 simulations were found to produce stable results and truncation of the distribution of construction factors had little impact on the resulting pavement strength distribution. Further research is recommended to better understand the distribution of asphalt modulus, as well as the direct engagement of design software for Monte Carlo simulation, in order to avoid the need for a pavement-specific prediction model.

Flexible pavements are considered more sustainable than concrete pavements primarily due to the higher long-term maintenance and rehabilitation costs associated with concrete pavements. Concrete pavements possess a higher modulus of elasticity, which allows them to distribute vehicle loads over a larger area, thereby enhancing the strength of the pavement. However, despite this advantage, their flexural strength is relatively low. As a result, there has been a growing focus on research to improve the flexural strength of concrete pavements to increase their overall performance and sustainability. This study aimed to reveal the effects of enhanced mechanical properties of concrete reinforced with glass fiber on concrete pavements, specifically under heavy vehicle loading as in real-world conditions. The impact of glass fiber on the thickness of both the concrete and base layers, as well as the quality of the base layer material and transverse joint spacing, was assessed. For this purpose, 3D finite element models were developed using ANSYS software, considering concrete thicknesses of 100, 150, and 200 mm, glass fiber ratios of 0%, 0.5%, and 1%, base layer elastic moduli of 100, 200, and 300 MPa, and transverse joint spacings of 300, 450, and 600 mm. It was determined that the concrete thickness and the base layer modulus of elasticity were the most influential factors in minimizing flexural stress, total deformation, and equivalent total strain. The glass fiber addition had a more notable impact on maximum principal stress, especially at the 1% ratio, but had a minimal effect on total deformation and strain. Transverse joint spacing had the least effect, although shorter spacings are still recommended to reduce the risk of transverse cracking in stiffer base layers.

Owing to the combination of bitumen aging, traffic loading, and environmental factors, the performance of asphalt will gradually deteriorate with time. However, characterizing the deterioration is still challenging. Aiming to reveal how the performance of asphalt pavement deteriorates with time, the AASHTO design equation was applied to investigate the evolution trend of pavement performance by adopting a reliability method in terms of freeze–thaw cycles. It was found that the combination of the rate of evolution and curvature could identify the abrupt change points and significant variation stages. Risk analysis was introduced to provide a novel method to evaluate the pavement performance evolution by identifying the change of the hazard rate and the cumulative hazard rate. It was found that the evolution curve of asphalt pavement strength reliability could be divided linearly during its life cycle, which can be extended to any n-stage linear deterioration model according to the actual situation. Moreover, reliability levels for pavement strength were also proposed in this research according to the integrated pavement travel and structure performance.

In this study, the effects of Fly Ash (FA) and Ground Granulated Furnace Slag (GGBFS) on design of concrete pavement are investigated. It has been observed how these mineral additives change the 7 days compressive strength and splitting tensile strength of the concrete pavement, the 28 days compressive strength, splitting tensile strength and bending strength of concrete pavement. The cement dosage is 350 kg/m3 and water/cement ratio is 0.42. Three concrete mixture are produced. The first concrete mixture does not contain FA and GGBFS (reference concrete). The second concrete mixture contains 20 percent of the Portland cement is replaced with fly ash. Finally, the third concrete contains GGBFS displaced at the rate of 20% with cement. Three different molds are used in experiments. The first is cubic mold whose dimensions are 150 mm. The second is cylinder mold whose diameter and length are 150 mm and 300 mm, respectively. Finally, the third is beam mold whose dimension of cross-section and length are 150 mm x150 mm, and 550 mm, respectively. The study was carried out according to the Specifications of General Directorate of Turkish Highways (GDTH) (2016).

The major problems related to roller compacted concrete (RCC) pavement are high rigidity, lower tensile strength which causes a tendency of cracking due to thermal or plastic shrinkage, flexural and fatigue loads. Furthermore, RCC pavement does not support the use of dowel bars or reinforcement due to the way it is placed and compacted, these also aided in cracking and consequently increased maintenance cost. To address these issues, high volume fly ash (HVFA) RCC pavement was developed by partially replacing 50% cement by volume with fly ash. Crumb rubber was used as a partial replacement to fine aggregate in HVFA RCC pavement at 0%, 10%, 20%, and 30% replacement by volume. Nano silica was added at 0%, 1%, 2% and 3% by weight of cementitious materials to improve early strength development in HVFA RCC pavement and mitigate the loss of strength due to the incorporation of crumb rubber. The nondestructive technique using the rebound hammer test (RHT) and ultrasonic pulse velocity (UPV) were used to evaluate the effect of crumb rubber and nano silica on the performance of HVFA RCC pavement. The results showed that the use of HVFA as cement replacement decreases both the unit weight, compressive strength, rebound number (RN). Furthermore, the unit weight, compressive strength, RN, UPV and dynamic modulus of elasticity of HVFA RCC pavement all decreases with increase in crumb rubber content and increases with the addition of nano-silica. Combined UPV-RN (SonReb) models for predicting the 28 days strength of HVFA RCC pavement based on combining UPV and RN were developed using multivariable regression (double power, bilinear, and double exponential models). The exponential combined SonReb model is the most suitable for predicting the compressive strength of HVFA RCC pavement using UPV and RN as the independent variable with better predicting ability, higher correlation compared to the single variable models.

This model predicts the compressive strength of concrete pavement modified with palm oil fuel as partial replacement for cement. The study monitors the strength development of concrete pavement varying with different percentage of [POFA].The study express the output of the modifier from graphical representation, where optimum strength were observed at 5% at curing age between [7, and 28days].The study has observed that the modifier applied as partial replacement of cement experienced decrease in strength as the percentage of [POFA] dosage increase, these condition were observed from the graphical representation such that gradual decrease were experienced between [10-20%].The declined in strength development from variation of water cement ratio were experienced between [0.40-0.50], the influences from variation of these mixed proportion were also monitored, these conditions were reflected on the output results from the designed mix, the developed model were subjected to simulation, these values were compared with pone et al 2018, where the early strength from 2.5-5% 0f [POFA] were also in agreement with partial replacement of silica fume that also experienced early attained strength, between [2.5-5%] variations from concrete pavement porosity were observed from the heterogeneity of the strength at different water cement ratios, including variation of compaction and placement of the materials. Keywords: modeling, palm oil fuel ash, compressive strength, water cement ratios

Every year, 2000 km length of trench is being excavated through an existing pavement in Iran for installing urban waste water pipelines. Many a times, these trenches are not filled back properly resulting in large permanent settlement in the pavement constructed above the trench. Geogrids have been used at the top of the base course to decrease the settlement. This article presents the observed settlements of unreinforced and geogrid reinforced pavement, monitored over a period of 12 months under the urban traffic load. Finite element (FE) analysis of the trench and the pavement, unreinforced and reinforced, under a transient pulse load is also carried out by using PLAXIS. It is observed that the vertical settlement can be greatly reduced by using geogrids in the pavement. The results obtained from case study and PLAXIS show that the geogrids improve the stiffness and strength of asphalt pavement and control the rut formation in the pavement.

In this study, an attempt has been made to optimize the early flexural strength of concrete pavement (CP) by using the Taguchi Method. The experiments were designed using an orthogonal array technique in L16 array with four factors, namely, the water/cementitious ratio of 0.30, 0.35, 0.40 and 0.45, four different types of gradations with maximum aggregate size of 32 mm, fly ash (FA) 0%, 5%, 10%, 15% and silica fume (SF) 0%, 10%, 20% and 30% by weight of cement. The response data were analyzed using an analysis of variance (ANOVA) technique by the Taguchi method. According to the ANOVA table, water/cementitious ratio and SF content play significant roles for early flexural strength of CP. Moreover, the optimum conditions were found to be 0.35 water/cementitious ratio, gradation with minimum content of fine aggregates, 5% FA content and 0% SF content at 7 days curing. Maximum flexural strength of 5.31 MPa was achieved at the optimum conditions.

Analysis of trials and tests carried out at Luton Airport in the United Kingdom has indicated that concrete pavers provide a surfacing for aircraft pavements which has certain advantages over the pavement quality concrete and bituminous surfaces normally used. An increase of 14% in pavement strength, in terms of its load classification number (LCN) has been measured after surfacing with concrete pavers. Some of the concerns of the FAA regarding the use of concrete pavers on aircraft pavements in the United States are considered.

This study provides an overview of how phase change materials (PCMs) can improve the resistance of concrete pavement to freeze–thaw cycles and mitigate the urban heat island (UHI) effect. The investigation covers different types of PCMs and methods for integrating them into concrete pavement, as well as the mechanical properties and compressive strength of concrete pavement when employing various PCMs. Prior studies have identified porous aggregates, microencapsulation, and pipelines containing liquid PCM as common approaches for PCM integration. Researchers have observed that the utilization of PCMs in concrete pavement yields favorable thermal properties, suggesting the potential for anti-freezing and UHI mitigation applications. However, the choice of PCM materials should be informed by local climate conditions.

Evaluation of the effects of silica fume and air-entrainment on deicer salt scaling resistance of concrete pavements: Microstructural study and modeling

Effective Repair and Refurbishment Compound for the Strengthening of a Road Concrete Pavements

Portland Cement Concrete (PCC) pavement was studied with incorporation of an environmentally friendly eco-additive, sodium acetate (C2H3NaO2). This additive was added to PCC pavement in three different percentages of 2%, 4% and 6% of binder weight. For a comprehensive elucidation of the eco-additive incorporation on the performance of PCC pavement, casted samples were cured in three different environments, namely: water, outdoors and pond water. Water absorption tests, flexural and compressive strength tests after 7 and 28 days of curing were conducted and results compared with the control samples without any addition of sodium acetate. Results demonstrated a significant improvement in the impermeability, compressive strength and flexural strength of PCC pavement when sodium acetate concrete is cured in a water bath and outdoors. However, no/little improvement in the impermeability, compressive strength and flexural strength was observed in sodium acetate samples that were cured in pond water. Microstructural analysis of treated samples by using scanning electron microscopy (SEM) illustrated the strengthening effect that sodium acetate provides to the pore structure of concrete pavement.

A recent demonstration of a noncomplex solution for monitoring concrete strengths in real time used concrete maturity technology. During a recent airfield concrete pavement construction project in Des Moines, Iowa, several commercially available maturity measurement devices were evaluated along with an innovative strength assessment and prediction system, Total Environmental Management for Paving. This field evaluation demonstrated that current maturity technology could be used to assess the strength of a concrete airfield pavement successfully in real time. Furthermore, the adoption of maturity-based technologies can expedite airfield repair and construction and can expand the knowledge of concrete pavement as it is placed.