Determining the influence of concrete drying shrinkage in the International Roughness Index of newly constructed rigid pavements in Bolivian Altiplano

In the last decade, the design and the construction of concrete pavements in Bolivia focused on prevention of fatigue damage of concrete by the design and construction of locally named "semi-short slabs" concrete pavements, a solution with slab size between traditional JPCP and short slab concrete pavements. Although the structural performance of these new pavements is adequate so far, it was observed that the length of the slab, which commonly is between 2.4 to 3.0 m, affects functional performance. Because of the slabs are affected by differential drying shrinkage, they develop permanent curling with wavelengths that have more influence on IRI with respect to other lengths due to the sensitivity of the Quarter-Car model. This article describes the studies conducted to determine the slab curling influence on IRI of concrete pavements built with semi-short slabs in the last years in the Bolivian Altiplano. Longitudinal profile data was collected by means of a laser profilometer in highway sections located in western Bolivia, in regions with high altitudes and arid climate. Based on profile information, mechanistic analyses were done in order to estimate the theoretical deflections along the slabs that correspond to the observed curling. Deflections calculated were then used to estimate a Pseudo Strain Gradient that represent the effects of curling along the evaluated sections. IRI related to slabs curling was calculated and compared to IRI calculated from artificially generated profiles for various slab lengths. Results indicate that slab curling of these pavements has an important influence on IRI of evaluated sections. Recommendations for specifications of new construction projects are presented.

FIBER-REINFORCED CONCRETE FOR RIGID ROAD PAVEMENTS MODIFIED WITH POLYCARBOXYLATE ADMIXTURE AND METAKAOLIN

Increasing the strength and durability of road surfaces is crucial. Therefore, the concrete compressive strength, flexural strength, frost, and abrasion resistance of fiber-reinforced concrete for rigid pavements are investigated in this study an experiment is performed based on an optimal plan, in which four factors of concrete composition are varied: the amounts of Portland cement, polypropylene fiber, metakaolin, and polycarboxylate type admixture. Experimental statistical models for investigating the effects of composition factors on concrete properties are established. It is discovered that owing to the use of metakaolin and a superplasticizer, the concrete compressive strength increases. Furthermore, the use of modifiers and fiber reinforcement increases the flexural strength, frost resistance, and wear resistance of concrete. X-ray phase analysis of the fiber-reinforced concrete structure confirm the effectiveness of the modifier effect, in particular the positive role of metakaolin as an active pozzolana. The developed fiber-reinforced concrete for rigid pavements with rational modifiers, depending on the Portland cement content, exhibits compressive strengths from 55 to 70 MPa, flexural strengths from 8 to 9.5 MPa, frost resistances from F350 to F450, and abrasion resistances from 0.3 to 0.4 g/cm2. Such properties ensure the high durability of fiber-reinforced concrete and allow it to be used on road pavements that support heavy loads and traffic.

Role of Geopolymer Concrete with GGBS in Rigid Pavements

In modern construction concrete is very expensive and popular material where cement is the main composite. Every year we are producing billion tons of concrete. Production of cement is responsible for too much of CO2 production, in other words it is also responsible for global warming. Mostly India is facing the problem of pollution. Researchers have done a great job and found many ways to replace cement. For making geopolymer concrete by products of different industries may be used like. Fly ash, rice husk. In this investigation geopolymer concrete is prepared with GGBS. GGBS is a by-product of steel industry. It holds the coarse and fine aggregates in the matrix. In this investigation geopolymer concrete is prepared with GGBS and advantages and disadvantages are also investigated. It was an observation that it has good results over other concrete. GGBS is a good replacement of cement and it will help in reducing the production of CO2. as a result of this global warming can be reduced. Keywords: GGBS, Slag, Aggregates, Slump, Geo Polymer

Using of Laser Scanners in Pavement Management

The presented article introduces the utilization of laser scanning technology in the field of pavement management (PM) systems. Thanks its many advantages that allow objectification of road surface characteristics in a more holistic and sophisticated way, right decision-making within the PM, both at the network and project level. Specifically, outputs from the installed road scanners, such as SRS, Trimble CX and Lynx SG1 Mobile Mapper, have been combined to improve the accuracy. There has been found data correlation dependence of the development of rut depth for non-rigid pavements by evaluation of data from measurements at the public transport stop Hurbanova in Žilina during the years 1994 to 2018.

Experimental Investigation on Fibre Reinforced Concrete Pavement Slabs Subjected to Temperature Gradient

A long lasting, reliable and economical transportation system is a critical component for the continuous movement of heavy traffic. Rigid pavements are made of concrete are widely for land transportation used because of its increased life, strength and it provides efficient movement of heavy traffic. Concrete is a brittle material and its low tensile strength leads to the formation of cracks, which is one of the main reason of concrete failure. Addition of fibre prevents the crack formation because fibres are crack arresters. Fibre addition increases the structural integrity of the pavement. Concrete slab in pavement structure experiences daily temperature fluctuations and results in the formation of temperature gradients in the slab. The objective of this study is to investigate the material properties of the three different fibres used in pavement slabs subjected to temperature gradient and the fibres used is coir fibre. Reduced cracks ensure pavement durability, reduced maintenance, improved performance, improved performance and ride quality. Keywords: Rigid pavements, Fibre Reinforced Concrete (FRC), Coir Fibre, Temperature Gradient, Pavement Slab.

Effects of Climatic Conditions and Temperature Gradient on Jointed Plain Concrete Pavement Slabs

A long lasting, reliable and economical transportation system is a critical component for the continuous movement of goods and services. Rigid pavements are widely used in construction world due to its high performance and serviceability. Traditional bituminous pavements and their needs for continuous maintenance and rehabilitation operations point towards the scope for cement concrete pavements. Cement concrete slab in a rigid pavement structure are exposed to different conditions at the surface in comparison to the bottom due to daily temperature fluctuations and results in the formation of temperature gradients in the slab. Transient gradients are due to the seasonal changes to which the slabs are subjected whereas permanent gradients are due to the slab condition during the setting of slab. The objective of this study is to determine the effect of temperature gradient and climatic conditions on a jointed plain concrete (JPC) pavement slab and to establish a proper temperature gradient chart which can be referred to depending on the climatic conditions existing in Kerala. A properly designed slab can reduce the formation of cracks and hence increase the life of slab. A detailed study in this area, can help in forming some codal provisions for the design of pavement slab depending upon the climatic conditions of Kerala. Keywords: Rigid Pavements, Bituminous pavements, Jointed Plain Concrete (JPC), Permanent gradients, Temperature Gradient