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This work focuses on the reuse of reclaimed asphalt pavement (RAP) in the production of self-compacting concrete (SCC) for usage in the construction of rigid pavements. The article first describes an experimental study where five SCC mixtures incorporating 0%, 20%, 40%, 60% and 100% volumetric substitutions of natural aggregates by RAP were formulated. Several characterisation tests in the fresh and hardened states were then performed. The results of all performed tests showed that RAP has a slight negative effect on SCC performance in the fresh state. The most significant reduction observed does not exceed 18% for slump-flow and 10% for L-shaped box values when total substitution is applied. Furthermore, the mechanical properties noticeably decrease with an increase in RAP content, with reductions of up to 37% in 28-d compressive strength and 23% in 28-d indirect tensile (IDT) strength observed in the case of full replacement. However, it is possible to formulate SCC mixtures even with 100% RAP substitutions and meet specifications for rigid pavement construction. In addition, modelling of the various mechanical characteristics made it possible to find out the reason behind the reduction in these properties with RAP content. In fact, the thin bitumen film around RAP particles weakens their surface adhesion with the hydrated cement paste. With the intrinsic RAP properties found, the hardened-state characteristics of any other SCC mixture incorporating RAP could be predicted. [ABSTRACT FROM AUTHOR]

This study assessed the performance of self‐compacting rubberized concrete against carbonation and chloride penetration. In addition to fresh‐state and compressive strength tests, durability of the studied mixes was evaluated by measuring carbonation and chloride penetration depths, total porosity, and pores'size distribution. It was found that an increase in rubber content leads to a decrease in compressive strength. However, stadequate strength for structural applications was achieved up to an incorporation of 15% rubber by volume. As for durability, the presence of rubber was found to enhance performance against carbonation, but to worsen the resistance to chloride ion penetration. [ABSTRACT FROM AUTHOR]

• PCM addition into concrete reduced its compressive strength. • PCM damaging during mixing does not alter its mechanical and hygric behaviour. • Porosity increased with PCM addition but remains within the typical concrete range. • Low permeability values indicates that pores are not interconnected. • Sorption/desorption isotherms confirm that the pores network is not connected. This study evaluated the compressive strength and hygric properties of concrete incorporating 0%, 3%, and 5% microencapsulated phase change material (PCM). Results show that compressive strength decreases with microencapsulated PCM addition, but remains satisfactory for usage as structural concrete. Porosity increases with microencapsulated PCM addition but remains in the range of that of ordinary concrete. For all tested concretes (control mix, mixes with damaged and undamaged microcapsules PCMs), very low gas-permeability was found; while sorption/desorption isotherms resulted in low moisture contents at the highest humidity level and the data followed a hysteresis loop indicating pore blocking mechanism. [ABSTRACT FROM AUTHOR]

The accuracy of existing theoretical models to predict the compressive strength of concrete relies mainly on the accuracy of the used properties of its constituents. However, these models could be used at first to backcalculate the properties of aggregates from a given rock formation. Then, the compressive strength of any type of concrete made using those aggregates could be accurately predicted, using the already established properties. In this research, the compressible packing model and its extension to include non-optimised mixes (containing more than 10% filler) was used to mechanically characterise aggregates. Two procedures are described to backcalculate the parent rock compressive strength from compressive and/or indirect tensile strengths of concrete mixtures. Five different rock formations were used (three limestone, one marly limestone, and one dolomitic limestone). The first procedure uses compressive strength data for a concrete mixture at two different ages, while the second procedure uses compressive and indirect tensile strengths data from two concrete mixtures. Results show that both procedures provide a good estimate of the parent rock compressive strength. [ABSTRACT FROM AUTHOR]

This paper presents the findings of an experimental study performed on sand concrete reinforced with polypropylene fibres, which is a fine concrete containing only sand as aggregate. The material is intended to be used for the construction of rigid pavements for secondary roads. This material is considered ecological since it saves on the consumption of coarse aggregates, which natural resources are getting scarce, and it is based on two materials that are considered as wastes, namely sea-dredged sand and quarry sand. The performed tests include compressive strength, indirect tensile strength, three-point bending flexural strength, modulus of elasticity and free shrinkage. It was found that polypropylene fibres slightly reduce the mechanical properties of the material but significantly enhance its shrinkage behaviour as well as its toughness and therefore ductility. It was concluded that sand concrete reinforced with 1% (by weight of cement) polypropylene fibres is a suitable material for constructing rigid pavements for low-traffic roads. [ABSTRACT FROM AUTHOR]

A detailed laboratory investigation of waste tire rubberized self-consolidating concrete (SCC) was carried out in two phases. The first phase focused on proportioning rubberized mixtures using local materials that meet European specifications for SCC in terms of flow, passing ability, and resistance to segregation. This phase resulted in a selection of four mixtures: one control mixture (no rubber) and three rubberized mixtures containing 10, 20, and 30% waste tire rubber. The second phase of testing concentrated on analyzing the hydration process of the retained mixtures using the results of the semi-adiabatic calorimetry test as well as performing conventional mechanical tests. Results show that rubber particles do not affect concrete hydration rate, but do decrease the adiabatic temperature, given its high specific heat. As reported by other researchers, conventional mechanical properties were also found to decrease as the percent of rubber increases. [ABSTRACT FROM AUTHOR]

Compacted sand concrete is being researched for potential usage in road construction because of the overexploitation of quarry gravels and the risk of a shortage in gravel resources in many countries throughout the world. This paper describes the steps followed to validate the use of such material from the proportioning to the performed mechanical tests (compressive strength, indirect tensile strength, flexural strength, and Young's modulus). This study also describes the development of an economic test setup to test the fatigue properties of compacted sand concrete. The developed machine produced repeatable results and was able to generate the fatigue curves for a conventional concrete mixture and three different compacted sand concrete mixtures. Two of the tested sand concrete mixtures were made using crushed sand from two different quarries, whereas the third one was made using a mixture of crushed sand and desert sand. The encouraging fatigue results, as well as the acceptable initial construction costs, validate the use of compacted sand concrete in pavements. [ABSTRACT FROM AUTHOR]

Abstract: Compacted sand concrete is being researched for potential usage in road construction because of shortage in gravel resources in many countries. However, one of the problems for this material with such application is shrinkage cracking. This paper presents the results of the unrestrained shrinkage test performed on three different compacted sand concrete mixes. Two existing shrinkage prediction models, namely the ACI 209 and the CEB 90, were used to fit the measured shrinkage data. The CEB 90 model with an application of a correction factor was found to perform well with compacted sand concrete. Based on the results of the shrinkage tests, joint spacing between compacted sand concrete slabs was calculated. [Copyright &y& Elsevier]