No abstract is provided for this article.
No abstract is provided for this article.
This research investigates the mechanical properties of concrete blocks made with industrial by-product materials including construction waste, washed cement fines from ready-mix concrete plants, brick dust, and ladle furnace slag. The study examines factors influencing compressive strength, void content, absorption capacity, and boiling water absorption,...
This study evaluated the corrosion of steel in seawater-mixed concrete with different interfacial transition zones (ITZs) by measuring different corrosion parameters. The ITZs around the steel bars were intentionally varied by applying cement paste coating around the steel bars, which had various water to cement ratios (W/Cs = 0.3, 0.5, and 0.7). Four...
The fresh and mechanical properties of concrete made with brick aggregates of eight different maximum aggregate sizes (MAS), i.e., 10 mm, 12.5 mm, 19 mm, 25 mm, 37.5 mm, 50 mm, 63 mm, and 75 mm, were investigated. The other parameters studied were sand-to-aggregate volume ratio (s/a) (0.40 and 0.45), W/C (0.45, 0.50, and 0.55), and cement content (375 kg/m3 and 400 kg/m3). In total, 80 different concrete mixes were studied; the perimeter of the interfacial transition zone (ITZ) along the brick aggregates was quantified with an image-analysis software and the microstructure along the ITZ was investigated using a scanning-electron microscope (SEM) to corroborate the hardened properties of the concrete. Although larger MAS leads to greater slump in concrete, its effect on hardened properties is linked to other design parameters. For a cement content of 375 kg/m3 and W/C of 0.45 and 0.50, the compressive strength of concrete increases (by up to 5%–15%) with increases in MAS of up to 37.5 mm irrespective of s/a (0.40 and 0.45) and then reduces gradually. For all other cases, the compressive strength of concrete is reduced with increases in MAS. The SEM imaging confirmed the presence of weak and porous ITZ and the deposition of ettringite in the voids left by entrapped bleed water under large aggregates. The compressive strength also increased with increases in s/a from 0.40 to 0.45, predominantly for smaller MAS. Correlations between mechanical properties of concrete and stress–strain curves are proposed for different MAS.
To understand the prospect of recycling recycled brick aggregate (RBA), concrete samples were collected from 50 demolished building sites over a period of
To address SDG12 (ensure sustainable consumption and production patterns), and to provide technical evidence for alternative concrete constituents to traditional natural river sand, stone fine aggregate (SFA), brick fine aggregate (BFA), ladle-refined furnace slag aggregate (LFS), recycled brick fine aggregate (RBFA), and washed waste fine aggregate (WWF), ready-mix concrete plants were investigated. Concrete and mortar specimens were made with different variables, such as replacement volume of natural sand with different alternative fine aggregates, water-to-cement ratio (W/C), and sand-to-aggregate volume ratio (s/a). The concrete and mortar specimens were tested for workability, compressive strength, tensile strength, and Young’s modulus (for concrete) at 7, 28, and 90 days. The experimental results show that the compressive strength of concrete increases when natural sand is replaced with BFA, SFA, and LFS. The optimum replacement amounts are 30%, 30%, and 20% for BFA, SFA, and LFS, respectively. For RBFA, the compressive strength of concrete is increased even at 100% replacement of natural sand by RBFA. For WWF, the compressive strength of concrete increases up to a replacement of 20%. Utilizing these alternative fine aggregates can be utilized to ensure a circular economy in construction industries and reduce the consumption of around 30% of natural river sand.
This paper investigates the possibility of recycling of demolished concrete blocks made with brick aggregates as coarse aggregate. For this, demolished concrete blocks from seventeen different demolished building sites were collected and crushed into coarse aggregates. As virgin aggregate, first class brick aggregates (normal brick aggregate) were investigated. About 200 concrete cylinders were made using normal and recycled brick aggregates with W/C= 0.45 and 0.55. Test items include slump, unit weight, compressive strength, tensile strength, Young’s modulus, and stress-strain curve. For the same W/C, recycled brick aggregate concrete shows lower compressive strength and Young’s modulus compared to the normal brick aggregate concrete. The average strength of recycled brick aggregate concrete is found at 25.5 MPa (3700 psi) and 19.05 MPa (2762 psi) for W/C=0.45 and 0.55 respectively. The results indicate that recycled brick aggregates can be utilized for new construction works as normal brick aggregates.
No abstract is provided for this article.
Effects of maximum aggregate size (12.5mm, 19.0mm, 25.0mm, 37.5mm, and 50.0mm) on properties of concrete made with different sand to total aggregate volume ratio (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375kg/m3 and 400kg/m3) were investigated. Considering the variables, a total of 552 concrete cylinder specimens of diameter 100mm diameter and height 200mm were made for 52 numbers of independent cases. Brick aggregates were tested for specific gravity, absorption capacity, unit weight, and abrasion resistance. Concrete specimens were tested for compressive strength, stress-strain curve, splitting tensile strength, and Young's modulus. Results have revealed that for higher cement content (400kg/m3), concrete made with small aggregates give more compressive strength. However, for a cement content of 375kg/m3, and W/C ratio of 0.45, the compressive strength is increased with an increase in maximum aggregate size up to 37.5mm. The compressive strength of concrete increases with an increase in s/a ratio from 0.40 to 0.45. Relationships between mechanical properties of concrete, and stress-strain relationships are proposed for different maximum aggregate sizes.
Repair of heritage stone masonry structures sometimes involve anchoring the walls, to prevent from separation and to increase integrity of the walls. Performance of these anchors significantly depends on their ability to resist debonding forces induced from environmental freeze-thaw. Before choosing any anchoring materials for a heritage structure repair, capability of these materials in forming a sound bond with the existing masonry materials of that structure needs to be examined. A study was conducted at the University of Manitoba in collaboration with the Public Works and Government Services Canada (PWGSC), to test the behaviour of several anchors in stones. Conventional anchoring materials consist of steel, grout, and epoxy. On the other hand, suitability of Glass Fibre Reinforced Polymers (GFRP) to overcome the corrosion related problems of steel is well established. Keeping this aspect in mind, innovative anchors made from GFRP bars were also incorporated in this research program. Experimental program involved small scale replication of stone-anchor assemblies followed by monitoring of these assemblies for failures, while they were exposed to environmental chamber freeze-thaw cycles, in the W.R. McQuade Structures laboratory of the University of Manitoba. Varying rate of change of temperature and level of relative humidity were maintained in the environmental chamber during these exposures. At the end, monitoring data were analyzed to draw conclusions.
