Papers by Author: M. Hulusi Ozkul

Abstract: Ethylene vinyl acetate (EVA) was used in the amounts of 5, 10 and 15% of the cement content in the production of polymer cement mortars. Besides, nanosilica, in three different sizes of 35, 17 and 4 nm, were included in the mortars. The addition of nanosilica particles in polymer cement concretes and mortars affects both fresh and hardened state properties. The extremely high surface area of nanoparticles increases the water demand; hence to obtain a workable mixture it is necessary to increase the superplasticizer used. In the hardened state, the strength and impermeability properties improve due to both pozzolanic reaction and filler effect of nanosilica particles as well as polymer film formation. The flow properties in the fresh state and flexural and compressive strength properties in the hardened state were determined.

Abstract: Macro-defect-free (MDF) cements are cement-polymer composites and were developed by Birchall et al. three decades ago. The composites are produced by mixing small amounts of polymer and water with cement. However, they have a different production method than that of cement pastes, which was inspired by rubber production. Mixtures of cement, polymer and water are processed by using a two-roll mill. The composites are known with their high flexural strengths. Unfortunately, there are not any known commercial products using MDF cements because of their poor durability under moisture. In this study, MDF cements were prepared by using poly(vinyl alcohol--vinyl acetate) PVA, calcium aluminate cements and two different types of epoxy resins. Epoxy resins were a diglycidyl ether of bisphenol A and a mixture of a diglycidyl ethers of bisphenol A and F. Durability performance was compared with respect to biaxial flexural strengths, contact angle and atomic force microscopy (AFM) for the specimens stored in water.