Abstract
This investigation presents the influence of various types of nanoparticles on the performance of ultra high performance concrete (UHPC). Three nanoparticles from waste materials include nano-crushed glass, nano-metakaolin, nano-rice husk ash were prepared using the milling technique. In addition, nano-silica prepared using chemical method at the laboratory is implemented to compare the performance. Several UHPC mixes incorporating different dosages of nanoparticles up to 5% are prepared and tested. Mechanical properties, durability as well as the microstructure of UHPC mixes have been evaluated in order to study the influence of nanoparticles on the hardened characteristics of UHPC. The experimental results showed that early strength is increased by the incorporation of nanomaterials, as compared to the reference UHPC mix. The incorporation of 3% nano-rice husk ash produced the highest compressive strength at 91 day. Microstructural measurements using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), and Thermogravimetric Analysis (TGA) confirm the role of nanomaterials in densifying the microstructure, reducing calcium hydroxide content as well as producing more C-S-H, which improves the strength and reduces the absorption of UHPC. Nanoparticles prepared from waste materials by the milling technique are comparable to chemically prepared nanosilica in improving mechanical properties, refining the microstructure and reducing the absorption of UHPC.
Highlights
The ongoing development of construction materials led to improvement in the concrete characteristics and production of new types of concrete with superior properties such as ultra-highMaterials 2020, 13, 4530; doi:10.3390/ma13204530 www.mdpi.com/journal/materialsMaterials 2020, 13, 4530 performance concrete (UHPC)
Incorporating 3% nano-rice husk ash. This investigation studied the influence of different nanoparticles prepared from waste materials on the properties of ultra high performance concrete (UHPC)
Mixes incorporating nano-silica, nano-waste glass and nano-Metakaolin achieved the maximum strength at 1% nano silica (NS), 1% NWG and 1% NMK due to their compactness, whereas, nano-rice husk ash increases the compressive strength, especially at later ages due to its characteristics of saving water at early ages and promoting them to share in the hydration process, with the optimum strength obtained at 3%
Summary
The ongoing development of construction materials led to improvement in the concrete characteristics and production of new types of concrete with superior properties such as ultra-highMaterials 2020, 13, 4530; doi:10.3390/ma13204530 www.mdpi.com/journal/materialsMaterials 2020, 13, 4530 performance concrete (UHPC). The optimizing of packing density of concrete constituents results in UHPC with compacted microstructure, which ensures both ultra-high durability and ultra-high mechanical properties [2] It has many advantages over traditional concrete; higher strength, higher ductility and energy absorption, long service life due to dense microstructure and superior durability, self-healing ability associated with a high amount of unhydrated cement [3]. In some applications special types of concrete are needed to meet the extreme working conditions of high strength and to resist severe uncontrolled conditions [4,5,6,7,8,9] This is where the new invention of UHPC can be described as a practical and urgent solution. Despite the superior properties of UHPC, their extensive applications are limited due to some drawbacks, including technical problems such as high binder consumption in addition to expensive material cost
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