Abstract
Reinforced concrete is regarded as one of the ideal structural materials which comprises concrete with high compressive strength and reinforcing bars with high tensile strength. However, concrete has been pointed out that it consumes a large volume of energy and emits a lot of carbon dioxide during its manufacturing. In order to lower such environmental burdens of concrete structures, a number of studies and approaches have been carried out. The voided slab is also suggested as a new method to reduce the environmental burden since voided section of the slab would use less concrete compared with the normal reinforced concrete slab. However, no studies have evaluated the CO2 emissions and environmental performance of voided slabs. The purpose of this study was to evaluate the structural performance of voided slabs and empirically corroborate their environmental influence. The flexural performance test was carried out based on the variables of the depth of slab, types of the void former materials, and the hollowness ratio. In addition, comparison of the emission of CO2 was also performed by considering the hollowness ratio and types of void former materials over the normal reinforced concrete slab. The structural performance of the voided slab was similar or slightly higher than the normal reinforced concrete slab. The yield strength of specimens was increased approximately 10∼30% over the anticipated yield strength. Based on this result, it is considered that the voided slab would be sufficient to structural performance and beneficial to plane planning in buildings. In general, it is considered that the voided slab would be beneficial to both structural and environmental aspects. However, the test results in this research showed that the voided slab would emit more carbon dioxide emissions compared to the normal reinforced concrete slab. The main source of more CO2 emissions in the voided slab was the anchoring materials. In this research, wires were used to fix the void former materials to the reinforcing bars. In order for the voided slab to become a more eco-friendly and sustainable material, new anchoring methods such as use of recycled materials, new void former materials without anchoring, or other eco-friendly materials should be applied to reduce the emission of CO2.
Highlights
Reinforced concrete is regarded as one of the ideal structural materials and is commonly used in the architectural, engineering, and construction (AEC) industry [1, 2]
The depth of slab, type and presence of void former materials, and hollowness ratio were used as the main variables to test the flexural strength of concrete slab specimens. e details of the dimensions and properties of the specimens are summarised in Table 1, and Figure 1 shows cross-sectional diagrams of the specimens. e tested specimens were 4230 mm in length and 700 mm in width. e depth of slabs varied between 169 and 210 mm
In order to receive the displacement of the slabs, a linear variable differential transformer (LVDT) was installed under the specimens. e LVDT in this research was able to measure up ranges of 200 mm of the displacement. e data were gathered by a data logger (Tokyo Sokkie)
Summary
Reinforced concrete is regarded as one of the ideal structural materials and is commonly used in the architectural, engineering, and construction (AEC) industry [1, 2]. Various other researchers have proposed new methods to reduce the amount of concrete, such as replacing normalstrength materials with high-strength materials, using byproducts and recycled materials, and designing optimal structural systems to minimise construction materials [8,9,10,11,12,13,14]. In order to reduce embodied carbon during building construction, various approaches have been suggested and researched, such as the using high-performance materials, material replacement, implementation of optimal design, and the application of structural system alternatives [5, 25,26,27,28]. Cho and Na [12] indicated that the application of high-strength reinforcing bars would reduce carbon dioxide emissions in reinforced concrete structure buildings. Apartment houses built with a column and beam system emitted less CO2 than bearing wall systems. ey suggested that the application of high-strength concrete and adding blast furnace slag would be beneficial to reduce CO2 emissions
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