Description:
•Compaction improves splitting resistance of vertically cast specimens.•Top-cast specimens have a lower splitting resistance than bottom-cast specimens.•Higher splitting stress is generated orthogonal to the plane of the textile.•The main cause of splitting failure is the fiber strand’s varying cross-section.•Bond distribution depends on the cross-section variation along the fiber strand. Textile-reinforced concrete is an innovative combination of high-performance fine-grained concrete and textile reinforcements. This combination allows the production of thin, efficient, and durable structural elements. Impregnation is commonly used to improve the textile's mechanical performance. When stiff impregnation materials are used, a fiber strand with high transverse stiffness is formed. Textile-reinforced concrete structures with such fiber strands are prone to splitting failures. This paper investigates splitting failure in textile reinforced concrete experimentally and numerically. In the experimental part, the effect of concrete compaction, casting method, and position are studied as parameters. Finite element analysis is performed to investigate failure mode, tensile and bond stress distributions, and the effect of the varying cross-section of the fiber strand. Compaction improved the splitting resistance for the vertically cast specimens. The compacted vertically cast specimens showed a higher splitting resistance than their horizontally cast equivalents. The finite element model indicated that the main cause of splitting failure is the textile reinforcement's varying cross-section coupled with its flat elliptical shape. The model also showed that the bond stress distribution depends on the fiber strand's geometric configuration.
Description:
Concrete is the most commonly used construction material because of its various advantages, such as versatility, familiarity, strength, and durability, and it will continue to be in demand far into the future. However, with today’s sensitivity to environmental protection, this material faces unprecedented challenges because of its high greenhouse gas emissions, mainly during cement production. This paper investigates one of the promising cement replacement materials, alkali-activated cement (AAC) concrete. Being produced mainly from byproduct materials and having a comparable structural performance to conventional concrete, AAC concrete can transform the construction industry. Mechanical properties such as compressive and flexural strength and the relationship between them are studied. Different source materials such as fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF), and Metakaolin (MK) are used. The effect of the source materials and the activator solutions on the concrete performance is studied. Furthermore, the freeze-thaw resistance of the concrete is studied. The study results showed that the behavior of AAC depends highly on the source material combinations and type used. The effect of the alkaline solution is also dependent on the source material used. Mixes with higher GGBS content showed the highest strength, while mixes with MK showed the highest flexural strength. The freeze-thaw test results showed that proper design of AAC concrete with lower water content is critical to achieving a good resistance.
Description:
Porosity is among the basic physical parameters widely used in evaluating the strength characteristics of building stones. Based on the geometric shape of the stone specimen, there are two procedures for determining the porosity: 1) measurements on specimens with regular shapes and 2) measurements on specimens with irregular shapes. The present study correlates the strength characteristics of stones and porosities measured from specimens with regular and irregular shapes. To this end, samples of carbonate stones were collected from different locations in Iran. The porosity of the samples was measured for specimens with regular (nr) and irregular (nir) shapes. Next, the strength characteristics of the samples, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and point load index (PLI), were determined. Results revealed that for all samples, nr has lower values than nir. Based on the scanning electron microscope (SEM) micrographs, this difference is due to the filling of some pore spaces of the specimens with regular shapes during their preparation by the coring machine. UCS, BTS, and PLI(50) were correlated with nr and nir using simple regression analyses. The accuracy of the correlation equations was compared based on their determination coefficient (R2) and diagonal line (1:1) measures. The findings indicated that nir provides higher accuracy than nr in evaluating the UCS, BTS, and PLI(50) of the samples. The effect of dry density (
Description:
Masonry units have been fundamental to building construction for over 6000 years, making them one of the oldest and most widely used materials in the industry. However, their production using ordinary Portland cement has significant environmental impacts, including high carbon dioxide emissions and depletion of natural resources. This highlights the need for more sustainable alternatives. One promising option is the use of recycled aggregates from construction and demolition waste in masonry unit manufacturing. This paper investigates the use of chipped waste timber as aggregates, bound together with geopolymer cement made from industrial by-products such as fly ash and slag. The result is a new type of masonry units, referred to as wood geopolymer masonry units (WGMUs), which were evaluated against established standards and compared with conventional masonry units (CMUs). The innovative WGMUs demonstrated improved ductility and reduced density compared to CMUs, making them easier to handle and lighter in construction. They also have a distinctive, rustic texture and consistent dimensions that meet Australian standards. Although WGMUs exhibited higher water absorption and drying contraction due to their wood content, these characteristics generally remain within acceptable limits, supporting their potential as eco-friendly construction materials. •Study the performance and characteristics of wood-geopolymer masonry units.•The presence of wood affects all the thermo-physical properties and durability.•Wood-geopolymer masonry units demonstrate remarkable ductility, characterised by a gradual failure pattern.•The size of the masonry units has a significant effect on the compressive strength.•The thermal conductivity of the wood-geopolymer masonry units ranged from 0.17 to 0.321 W/m.K at 23.8 °C.
Description:
Masonry units have been fundamental to building construction for over 6000 years, making them one of the oldest and most widely used materials in the industry. However, their production using ordinary Portland cement has significant environmental impacts, including high carbon dioxide emissions and depletion of natural resources. This highlights the need for more sustainable alternatives. One promising option is the use of recycled aggregates from construction and demolition waste in masonry unit manufacturing. This paper investigates the use of chipped waste timber as aggregates, bound together with geopolymer cement made from industrial by-products such as fly ash and slag. The result is a new type of masonry units, referred to as wood geopolymer masonry units (WGMUs), which were evaluated against established standards and compared with conventional masonry units (CMUs). The innovative WGMUs demonstrated improved ductility and reduced density compared to CMUs, making them easier to handle and lighter in construction. They also have a distinctive, rustic texture and consistent dimensions that meet Australian standards. Although WGMUs exhibited higher water absorption and drying contraction due to their wood content, these characteristics generally remain within acceptable limits, supporting their potential as eco-friendly construction materials. •Study the performance and characteristics of wood-geopolymer masonry units.•The presence of wood affects all the thermo-physical properties and durability.•Wood-geopolymer masonry units demonstrate remarkable ductility, characterised by a gradual failure pattern.•The size of the masonry units has a significant effect on the compressive strength.•The thermal conductivity of the wood-geopolymer masonry units ranged from 0.17 to 0.321 W/m.K at 23.8 °C.