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Highlights • The highest strength was obtained with TETA hardener, which has six functionalities. • Monofunctional diluent reduced the compressive strengths of TETA and MXDA mortars. • The addition of a diluent into epoxy mortars improved their flexural strength. • The highest adhesion strength was obtained with MXDA hardener and DGEBA resin. • Moderate to poor chemical resistance against formic and lactic acids were obtained. Abstract Three epoxy resins and three types of glycidylether-based reactive diluents were used together in epoxy mortars. Six different amine-based hardeners, four aliphatic and two cycloaliphatic, were used in the mixtures. Test results showed that a hardener with higher functionality results in mortars with higher strength. The combination of diluent and hardener was found to affect both the compressive and flexural strengths of the mortars. The adhesion strengths of the mortars (to a sand-blasted concrete surface) were obtained by pull-off test. It was found that lactic and acetic acids have different levels of destruction in the epoxy mortars. [ABSTRACT FROM AUTHOR]

Three types of epoxy resins, namely, diglycidyl ether of bisphenol A and F, and a third obtained by mixing the two resins, and three types of reactive diluents, based on glycidylether, were used to form epoxy mixtures. The effect of diluent content up to 15 wt% on the viscosities of the three epoxies was investigated. The flow properties of mortars prepared with epoxy, hardener, and diluent, as a binder, were compared with respect to the viscosity and molecular weight of the epoxies and diluents, as well as the viscosity and shape of the hardeners used. Six types of hardeners, including four aliphatic and two based on cycloaliphatic amine, were used in the production of mortars. Furthermore, the effects of the type of epoxy, content, type and functionality of diluents, and the functionality and molecular structure of hardeners, on the pot lives of the mixtures were examined. In this study, it is found that not only the viscosities of resin and diluents but also viscosities and molecular structures of hardener and accelerator are effective on the workability properties of epoxy mortars. [ABSTRACT FROM AUTHOR]

Abstract: Macro-defect free (MDF) cement is a high-strength cement–polymer composite produced by mixing cement (commonly calcium aluminate cement) with small amounts of polymer (commonly polyvinyl alcohol acetate) and water, applying high shear, and finally applying relatively low pressure (about 5MPa) and modest temperature (about 80–100°C). However, MDF cements lose considerable strength when exposed to water. The objective of this study was to explore the effects of cement and polymer compositions on flexural strength and water sensitivity. Calcium aluminate cements were used with Al2O3 contents between 42% and 79%. Production of MDF cement was successful with all cements, but the highest strength (268MPa) was obtained with 70% Al2O3 cement. Secondly, PVAs were used that differed in their degree of hydrolysis between 73% and 99%. Of these, the one with a moderate degree of hydrolysis produced the highest strength (228MPa). All mixtures had strength loss on exposure to water, but PVAs with moderate degrees of hydrolysis exhibited the lowest strength losses (50–60%). [Copyright &y& Elsevier]

Abstract: Molasses, a by-product of sugar industry, increases the fluidity of fresh concrete, and also delays the hardening time of cement paste. In this study, the molasses were determined from three different sugar production factories. A normal water-reducing admixture, based on lignosulphonate, has been used in the control mixture. Setting times of cement pastes prepared with molasses at three different dosages (0.20, 0.40, and 0.70 wt.% of cement content) were determined and it was found that molasses addition causes considerable increase in both initial and final setting times. Workability tests, as well as bleeding tests, were carried out on fresh concretes prepared with three molasses and also with lignosulphonate-based admixture. Flexural and compressive strengths were determined on hardened concretes at both early ages (1, 3, and 7 days), and moderate and later ages (28, 90, 180, 365, and 900 days). The permeability and durability properties of concretes have been investigated by using sorptivity, drying shrinkage, freezing¿thawing, wetting and drying, carbonation, and sulfate attack tests. The strength of concretes with molasses showed slight increase at all ages, except early age, with respect to the control mix and no adverse effect has been experienced on the durability properties over a long period of time (900 days). [Copyright &y& Elsevier]

The effect of initial water-curing period on the strength properties of concretes was investigated. Three types of cement, one ordinary Portland cement (OPC) and two natural pozzolanic cements (blended and trass cements), were used in the concrete mixtures. Six different curing regimes were applied to the specimens, the first of which was continuous water storing, and the second continuous air storing. In the remaining four regimes, the specimens were stored under varying initial water-curing periods of 3, 7, 14, and 28 days, respectively. The compressive strength tests were carried out on the cubic specimens at the ages of 7, 14, 28, 90, and 180 days. The variation of compressive strength with time was evaluated by using a semilogarithmic function and the strength-gaining rates were calculated by using this equation for different curing conditions. It was found that poor curing conditions are more adversely effective on the strength of concretes made by pozzolanic cements than that of OPC, and it is necessary to apply water curing to the former concretes at least for the initial 7 days to expose the pozzolanic activity. However, when the pozzolanic cement concretes have sufficient initial curing, they can reach the strength of OPC concretes in reasonable periods of time. [Copyright &y& Elsevier]

• The same penetration bitumens from different origins can have distinct chemistries. • Bitumen composition, amounts of polymer and wax were chosen as variables. • Shear rheometer, Viscosity, Elasticity and Creep stiffness were used as responses. • The most effective independent parameters were determined by the optimization study. The effect of bitumen chemical composition, amounts of elastomeric polymer and a kind of warm mix additive on the Dynamic Shear Rheometer, Bending Beam Rheometer, Elastic Recovery and Viscosity responses of the bitumen binders was investigated by using Response Surface Methodology. The individual effects of parameters on response functıons were analyzed. Then the optimization was performed by the simultaneous analysis within the desired limits and optimum values of variables were determined as GI: 0.988, SBS: 3.2% and Wax: 3%. The performance grade of neat bitumen was increased from PG70-22 to PG82-16 by modification at optimum conditions. [ABSTRACT FROM AUTHOR]