The present work aims to contribute to the study and development of methodologies for shrinkage tests of self-compacting concrete (SCC) using the addition of polypropylene (PP) microfibers as a variable to validate the correlations between the shrinkage tests. The objective of this work was to evaluate, through correlations between the area and the age at which the cracks appeared, the role of PP fibers as a control for this pathology. Reference SCC traces with additions of 6 mm and 12 mm microfibers were created for this purpose. For the shrinkage tests, the criteria of the ASTM C1579:2013 (plates) and ASTM C1581:2016 (rings) standards were used. The microfibers showed a significant reduction in cracks in the SCC, its reduction rate ranging from 40% to 70%, also presenting a delay in its appearance, which varied from 9 to 20 days for the appearance of the first crack.

Recycled crumb rubber can be sustainable used in mortar both to mitigate nature aggregate consumption, reducing environmental pollution, as well, to improve the acoustic and thermal performance of buildings, without damaging its mechanical properties. This paper explores workability, microstructure, mechanical, thermal and acoustic properties considering increasing contents of crumb rubber (0%, 5%, 10%, 15% and 20% replacement, by volume, of fine aggregate). Mortar characterization tests were carried out in the fresh and hardened state. It has been found that replacing the aggregate with scrap tyre rubber reduced the compressive strength on average 12% and 67% and for tensile strength 35% and 53%, for the contents of 10% and 20% respectively, compared to the reference. Furthermore, it was found that the reductions in thermal conductivity reached 16% and 29% and an increase in acoustic attenuation on average 12% and 13%. Moreover, scanning electron microscopy images were analyzed, justifying the mechanical results obtained. Although the experimental results indicated that the workability and mechanical strengths decreased with the increase of rubber replacement rate, the studied mixtures met the standard specifications, and thus suitable for walls and ceilings coating applications, improve the acoustic and thermal performance of buildings and as a sustainable material.

Concrete structures are susceptible to several factors during their life cycles, which can cause various problems. This situation can be avoided in many cases if Structural Health Monitoring (SHM) is used. However, such monitoring is often expensive due to the large number of sensors and the use of data acquisition systems (DAQ). In this context, self-sensing cement composites (SSCCs), monitoring themselves without sensors by incorporating conductive fillers in their composition, provide a better piezoresistive effect. In this research, the Arduino platform and analog to digital converters (ADC) modules were tested, and a prototype of a low-cost DAQ was developed for monitoring SSCCs. The devices were analyzed from the compression tests on the mortar specimens, and the results were compared to measurements obtained from the reference equipment (professional DAQ). The results showed a good sensitivity and an adequate correlation between both devices in some cases. It showed that the Arduino platform has the potential to be used in the experimental monitoring of SSCCs, however it needs to be combined with an ADC module.

The excessive production of new tires and the inappropriate disposal of waste tires have caused serious environmental and public health problems. To properly dispose of this environmental liability, these rubber residues have been used in cement composites to improve some of their properties in the hardened state. This study evaluates the incorporation of rubber and vermiculite residues in concrete in terms of mechanical and acoustic properties. Different concrete compositions were defined where rubber waste and vermiculite were used to replace the natural sand mass. To characterize the concretes, mechanical and acoustic tests, and analysis of the microstructure of the material were carried out to better understand its properties. An improvement in the acoustic properties can be seen in the composites with rubber and vermiculite. Thus, the great contribution of this research is the development of concrete compositions for acoustic barriers, technically viable, adding environmental benefits. problems liability state mass concretes tests Thus barriers viable benefits

The use of steel fibers in concrete affects its rheological properties in the fresh state and increases its energy absorption capacity in the hardened state. Rubber fibers come from tires and when incorporated into concrete, they promote an improvement in its damping factor. This work aimed to evaluate the use of rubber fibers on the mechanical properties of concrete reinforced with steel fibers. The evaluated properties were: compressive strength, tensile strength, static and dynamic modulus of elasticity and damping. The mixes of the tested concretes varied the consumption of steel and rubber fibers. From the results found, it can be seen that the rubber associated with steel fibers within the concrete mixtures improves the damping rates of the material. factor were strength found material

Structural health monitoring (SHM) techniques aim to detect and prevent failures in constructions, although their use may require many sensors, which makes this technique expensive and laborious. In this sense, the use of self-sensing cementitious composites based on the piezoresistivity effect could be a solution to some monitoring problems. Thus, the evaluation of the piezoresistive effect is commonly performed by analyzing the linearity between mechanical forces and the variation of electrical resistivity, through the coefficient of determination (R2). However, this work has been used to perform the analysis through Pearson's correlation in samples of self-sensing cementitious composites with graphite addition. The results obtained have shown that Pearson's correlation has the potential to be used for the evaluation of the correlation between electrical resistivity and mechanical forces to verify the piezoresistive effect in the cases studied.