Materials Science Forum Vol. 1084

Abstract: Steam curing is generally applied to improve productivity of precast concrete products. After steam curing, the products are stored outdoors as a secondary curing process until shipment. However, drying shrinkage and expansion of microcracks that occur during steam curing may inhibit strength improvement. On the other hand, water curing is also clearly effective as a secondary curing process. However, installing a water curing pool in a precast concrete plant is not easy due to limited space. Therefore, we focused on water sprinkling curing, which is relatively easy to perform without such restrictions. In this study, the effects of water sprinkling curing on the physical properties of mortar at the early age of steam curing were studied from the aspects of materials, mix proportions, curing conditions, and temperature of water used for sprinkling curing. As a result, it was confirmed that water sprinkling curing at an early age after demolding resulted in a rapid decrease in the temperature of the mortar surface layer. However, it was confirmed that the same conditions were effective in increasing compressive strength.

Abstract: Reinforced geopolymeric mortars were obtained by mixing mine tailing, fine sand, alpaca wool fibers ( in variable amounts) sodium hydroxide and potable water, it was possible to verify the effect of the addition of alpaca wool on the mechanical behavior in uniaxial compression of the mortars studied. The mechanical data found revealed a systematic decrease in the maximum stress as the volume of wool added in the mortar mixtures manufactured increased. On the other hand, a higher degree of deformation was verified in mixtures with a greater volume of added fibers, reaching deformation values of up to 5%. The maximum strength values were in the range of 4 to 21 MPa for samples with 8 and 0 Vol. % of added fibers, respectively. Among the microstructural characteristics of the mortars studied, a continuous binder phase corresponding to the geopolymer could be appreciated, with sand particles and wool fibers dispersed within the binder phase. The real density and average porosity of the reinforced mortars were 2.65 g/cm³ and 32%, respectively.

Abstract: The construction sector uses high quantities of raw materials and consequently the demolition sector generates huge amounts of waste. Envisioning the future of the construction sector, new Circular Economy Business Models should be implemented to contribute to the development of the sector. These Business Models will be based on innovative recycling techniques able to provide the technical requirements of the construction materials. This work aims to valorize ceramic and concrete wastes as aggregates for the mortar manufacturing. The chemical composition of these materials with high proportion of silica and very low quantities of sulfates makes them appropriate for their application. The wastes were previously crushed to the required particle size (6mm). The crushed ceramic waste presents an important fines proportion, which will increase the water consumption in the mortar mixes.

Abstract: This research aims to analyze the mechanical behavior of concrete reinforced with polyolefin fibers. The intention is to evaluate the possibility of using concrete as a structural material without steel bars in its interior. For this purpose, specimens with different dosages of polyolefin fibers were prepared, and bending and compression tests were carried out. The results show no significant increase in mechanical strengths, especially in bending, but it is interesting in the mechanical behavior after the first cracking. Controlling cracking is considered beneficial for sustainability.

Abstract: In general, steam curing is applied to improve the productivity of precast concrete products. After steam curing, products are stored outdoors for secondary curing before shipment. However, drying shrinkage and microcrack expansion that occurs during steam curing may impede strength enhancement. On the other hand, water curing is also clearly effective as a secondary curing process. However, installing a water curing pool in a precast concrete plant is not easy due to limited space. Therefore, this study focused on water sprinkling curing, which is relatively easy to perform without such restrictions. In this study, the effects of water sprinkling curing on the physical properties of mortar at the initial age of steam curing were investigated from the aspects of materials, mix proportions, curing conditions, and test piece dimensions. The results showed that water sprinkling curing increased the compressive strength by about 10% compared to curing under air. The effect of water sprinkling curing increased as the specific surface area of the test piece increased.

Abstract: The life cycle analysis (LCA) is a methodology that allows us to contemplate the environmental impact of a material during the different stages of the life cycle. The impact categories were used to measure the repercussions caused to the planet due to the high demand generated by construction materials. This study addressed the stages of a life cycle analysis, according to the ISO 14044 [1] standard, with the aim of evaluating, quantifying and comparing the environmental impacts associated with the manufacture of mortar with similar mechanical behavior: A conventional mortar and a geopolymeric mortar, the latter developed from a geopolymerization process of waste from the Peruvian mining industry [2,3]. The scope of the work sought to evaluate the main environmental impacts of both mortars, focusing on a "cradle to door" life cycle analysis. The application of LCA allowed optimizing the manufacturing process, reducing adverse environmental impacts. The results showed that the environmental impacts of the geopolymeric mortar presented better performance in the medium impact categories: Environmental impact and water consumption. On the other hand, the conventional mortar presented better performance in the stratospheric ozone depletion impact category.