Sugar industry waste bagasse contains many natural fiber materials, and the application of natural fibers in asphalt mixes such as SMA (Stone Matrix Asphalt) has become an attractive alternative for the construction of flexible pavements. This study aims to evaluate the mechanical performance of an asphalt mixture modified by incorporating 0.3% sugarcane bagasse fiber and with a size of 20 mm. The asphalt binder was submitted to penetration, softening point, and rotational viscosity tests to carry out this research, and the aggregates were characterized by specific mass, particle size, and absorption tests. Furthermore, the Superpave dosage was performed to produce the specimens to be evaluated in the splitting tensile strength test, resilient modulus, Marshall stability, and draindown sensitivity. As a result, the modified asphalt mixture presented a better performance in all evaluated strength tests and the leakage content within the standard specifications. Therefore, according to this, re-search, sugarcane bagasse fibers proved to be a viable alternative for SMA-type mixtures. Thus, the application of this material in asphalt paving and improving some essential characteristics can significantly reduce the environmental impacts generated by the inadequate disposal of these residues by sugar mills.
3 September 2021 in Arabian Journal for Science and Engineering
Cement is the costlier component of concrete, and its productive process causes considerable environmental impact. Thus, alternatives are studied to reduce the amount of cement used. An option is the use of optimized grain size curves of aggregates, aiming to achieve a higher compactness of concrete. An ideal grain size distribution results in a higher mechanical resistance of concrete, providing a reduction in cost and consumption of materials, and, consequently, in environmental impacts. Therefore, the present study aims to improve the properties of conventional concrete through optimized grain size distributions. In this research, concrete was produced with binary mixtures with rolled pebbles from Belém region, in Pará state, and ternary mixtures of granitic crushed stone from the metropolitan region of Recife, in Pernambuco state, and concrete properties in the hardened state were studied. The mix design IPT/EPUSP method was used and grain size composition, unit weight, water absorption by capillarity, and compressive strength tests were performed. It was observed an increase in compressive strength with for higher fine contents. Furthermore, for both aggregates studied, there was no loss in strength with the lower amount of cement used, due to the increased compactness of the concrete, indicated by the unit weight of the aggregate mixture. Therefore, the optimization of the grain size composition of the coarse aggregate provided a reduction in the cement consumption for the same required strength and for both analysed aggregates.
The depletion of natural resources and the increasing interest in reducing CO2 emissions have heightened the demand for alternative materials in concrete production. A viable approach is to lower the clinker-to-cementitious materials ratio by partially replacing clinker with supplementary cementitious materials (SCMs) and/or alternative materials such as aggregate mineral fillers (AMFs). As the availability of SCMs is expected to decline, AMFs have been increasingly explored, including those derived from aggregate processing and susceptible to alkali-aggregate reaction (AAR). However, the behaviour of AAR-reactive AMFs in concrete remains poorly understood. This paper summarizes the current state of the art and identifies knowledge gaps concerning the use of AAR-reactive AMFs, focusing on the roles of mineralogy, particle size, replacement content, and the test methods used to assess AAR-induced development and associated microscopic and mechanical deterioration. A consistent terminology is also proposed to support future research. Finally, a theoretical foundation to understand the role of AAR-reactive AMFs in mortar and concrete is provided, and the key knowledge gaps are discussed.
The present study aimed to develop a model to predict the service life of external wall coverings in mortar with paint finish, based on the state of degradation of 28 buildings in the city of Recife, Brazil. The area of the coating affected by different pathological manifestations was measured, and a numerical index to describe the severity of the degradation of the coating (Sw) was calculated. As a result of this index, degradation curves were constructed based on intrinsic factors (cardinal orientation, texture, color and presence of constructive details) and extrinsic factors (distance from the sea and proximity to polluting sources). In the analyzed samples, there was predominance of stains, and in less extent, cracks and detachments. The results showed that the cardinal orientation is the most influent characteristic in the durability of this coating system. The results obtained clearly demonstrate the applicability of the model in the study of the degradation of coatings, contributing to the development of maintenance actions focused on the most important factors in the degradation of coatings.