Abstract
This paper aims to investigate the effect of adding carbon nanotubes (CNTs) on the durability of latex modified mortar (LMM). Up to 2.5% of CNTs by wt. of styrene-butadiene latex (SBR latex) CNTs were added to latex modified mortar (LMM) specimens before they are subjected to two different thermal tests: freeze-thaw and thermal fatigue. LMM specimens were subjected to a number of freeze-thaw cycles according to American Society for Testing and Materials (ASTM) C-666 in order to simulate winter outdoor conditions in the United States (US) northern areas. Also, the specimens were subjected to thermal fatigue cycles similar to summer outdoor conditions. A large number of specimens were prepared in cubes, cylinders, and prisms, and were mechanically tested in compression, splitting tension, and flexure in order to evaluate the LMM specimens after the thermal exposure. Compression and tension specimens were tested after 50% and after 100% of the total number of cycles in order to assess the effect of the number of cycles on the mechanical performance. For LMM prims, dimensional stability was assessed first by monitoring the development of shrinkage strains during the application of thermal cycles. The LMM prisms were then tested in flexure after the completion of all the thermal cycles. The effectiveness of adding CNTs was evaluated by comparing between the performance of control LMM specimens and those with different CNTs contents. CNTs were found to alter the compressive strength, tensile strength, and flexural load carrying capacity of LMM specimens.
Highlights
Latex modified concretes (LMC), known as polymer modified concretes (PMC), have been introduced to the construction industry in the last century due to its relatively higher bond characteristics and better durability when compared to ordinary Portland cement concrete.LMC mixtures are typically constructed by replacing portion of the hydraulic cement paste by polymer additives
Cwirzen et al [15] investigated the effect of carbon nano- and microfibers (CMFs) on strength and residual cumulative strain of mortars that were subjected to freeze-thaw cycles
We examine the use of carbon nanotubes (CNTs) to improve the durability of latex modified mortar as an example for polymer modified cementitious (PMC) materials
Summary
Latex modified concretes (LMC), known as polymer modified concretes (PMC), have been introduced to the construction industry in the last century due to its relatively higher bond characteristics and better durability when compared to ordinary Portland cement concrete. A number of investigations have addressed the effect of adding nanomaterials, such as carbon nanotubes (CNTs), on the performance of the mortar or concrete mixture. It is theorized that this is because of a bridging effect of the carbon nanotubes and the decrease in the number of large pores that are associated with the addition of CNTs. Cwirzen et al [15] investigated the effect of carbon nano- and microfibers (CMFs) on strength and residual cumulative strain of mortars that were subjected to freeze-thaw cycles. Few or no studies addressed the effect of CNTs on the long term performance of PMCs. Different contents of CNTs were added to LMM mixtures and the durability of LMM mixes was evaluated through freeze-thaw and thermal fatigue tests, as discussed below
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