Alyaa Mohammed

Graphene oxide impact on hardened cement expressed in enhanced freeze-thaw resistance

AbstractGraphene oxide (GO) is a newly invented material with extraordinary properties. This paper presents the effect of graphene oxide addition on freeze–thaw resistance in hardened cement. GO is incorporated in the cementitious matrix in ratios of 0.01, 0.03, and 0.06% by weight of cement. Freeze–thaw cycle tests show a weight loss of approximately 0.8% after 540 cycles in the control mix compared to approximately 0.25% in 0.06% GO mix. Several tests were conducted to investigate the reasons behind this result. The tests included nitrogen and water adsorption, air content, and compressive strength. The results showed that GO mixes have finer pore structure than the control mix. Moreover, the results indicated that GO addition increases air content in the mix and shows high compressive strength compared to the control mix. The enhancement of freeze–thaw resistance due to GO addition can be because of the modification of pore structure where water hardly freezes in small pores. Also, the resistance of na...

Utilization of Graphene Oxide to Synthesize High-Strength Cement-Based Adhesive

AbstractAdhesive materials play a key role in any strengthening system for concrete structures. Traditional organic adhesives have a major limitation of poor fire resistance; hence, developing an a...

Assessing the Contribution of the CFRP Strip of Bearing the Applied Load Using Near-Surface Mounted Strengthening Technique with Innovative High-Strength Self-Compacting Cementitious Adhesive (IHSSC-CA)

Efficient transfer of load between concrete substrate and fibre reinforced polymer (FRP) by the bonding agent is the key factor in any FRP strengthening system. An innovative high-strength self-compacting non-polymer cementitious adhesive (IHSSC-CA) was recently developed by the authors and has been used in a number of studies. Graphene oxide and cementitious materials are used to synthesise the new adhesive. The successful implementation of IHSSC-CA significantly increases carbon FRP (CFRP) strip utilization and the load-bearing capacity of the near-surface mounted (NSM) CFRP strengthening system. A number of tests were used to inspect the interfacial zone in the bonding area of NSM CFRP strips, including physical examination, pore structure analysis, and three-dimensional laser profilometery analysis. It was deduced from the physical inspection of NSM CFRP specimens made with IHSSC-CA that a smooth surface for load transfer was found in the CFRP strip without stress concentrations in some local regions. A smooth surface of the adhesive layer is very important for preventing localized brittle failure in the concrete. The pore structure analysis also confirmed that IHSSC-CA has better composite action between NSM CFRP strips and concrete substrate than other adhesives, resulting in the NSM CFRP specimens made with IHSSC-CA sustaining a greater load. Finally, the results of three-dimensional laser profilometery revealed a greater degree of roughness and less deformation on the surface of the CFRP strip when IHSSC-CA was used compared to other adhesives.