Flexural modulus, polymer impregnation

Polymers. The purpose of adding polymers to the concrete matrix is to improve the characteristics of the fresh concrete (such as workability) and also to enhance the hardened properties such as flexural strength, modulus of elasticity and adhesive performance [8]. The incorporation of polymers into concrete may be in the form of polymer modified concrete (PMC), polymer impregnated concrete (PIC) or as polymer concrete (PC) [9], For this project, the objective was to develop an ultra-lightweight concrete material using Portland cement as the main binder modified with a suitable polymer - thus a PMC application. The polymer modifiers selected for the development of the ultra-lightweight thin filmed material were a commercially available SBR latex as well as a readily available acrylic polymer. 

A commercial paper-like sheet of kenaf fibre was converted to a composite material by impregnation with a solution of a commercial L-PLA in dioxane solution (Nishino et al, 2002). Following this procedure, a composite material with 70% v/v fibre content was obtained. Tensile tests showed that a maximum tensile stress of about 60 MPa was found for the best composite material, comparing with a value of about 20 MPa for the unreinforced polymer processed in the same way. Similarly, a tensile modulus of about 6 GPa for the kenaf-PLA composite compared with a value of just over 1 GPa for the unreinforced polymer. The authors concluded that good stress transfer fi om the resin to the matrix had been obtained. In research by Shibata et al (2003), a flexural modulus of 5.5 GPa was achieved at 20% w/w abaca fibre content in a PLA composite. This result compares with a flexural modulus of 3.5 GPa for the unreinforced pol3mier. A further increase in flexural modulus was obtained when... 

Steel fiber has been used to reinforce concrete. When 10-mil square bar 2 inches long is incorporated into concrete to the extent of 2% by volume, the modulus of rupture (flexural strength) increases by a factor of 2. When impregnated with polymer the fiber reinforced concrete-polymer increases the modulus of rupture by another factor of 2.5. Thus, an over-all increase by a factor of 5 in the flexural strength is achieved... 

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