An investigation of mechanical and durability properties of steel fiber reinforced cement-based grouts in different curing conditions

This thesis presents the results of an experimental program designed to investigate the influence of steel fibre reinforced cement based grouts in different curing conditions on mechanical and durability properties. Two types of grout were used in this study: firstly a proprietary grout commonly used in structural applications, followed by an alternative grout mix produced from conventional materials was designed. Grout mortars are used for different purposes in different areas such as base plates of machines, prefabricated structures, precast bridge decks, double-deck tunnel linings, offshore wind turbines, concrete improvement and repair. Especially in marine structures are affected by chemical and environmental attacks in aspect of durability properties when long term is considered. Like this applications, curing of grout materials is highly significant process. It is also known that hydration reaction is impacted by curing. In order to continuous hydration of cementitious materials and eventually to gain strength and durabillity needs proper curing. When the curing conditions were examined, it was the wet covering condition that provided the best strength and durability properties. Continuous water curing is less rather than wet covering, more than curing compound condition. Air curing condition gived negative results rather than others. Curing compound is the answer to the many problems faced in construction industries due to lack of proper curing, lack of water in certain areas and it is an alternative to conventional curing cement based grout in desert regions where scarcity of water is a major problem. Curing compound is more economical because it eliminates the curing charges. Spray application reduces labor costs, eliminates the need for alternative curing systems. Flow table and bleeding tests had be applied after mixing grout control and with micro steel fibre additions to investigate fresh properties. Steel fibers affected fresh state performance adversely and this negative effect. After placing and demolding of specimens, they were be exposed four different curing conditions until the ages of test the specimens: These are immersion in water curing at 20 oC±3, no less than 95% RH; covering with wet burlap and polythene sheet; curing compound apply, keeping under laboratory conditions; respectively. Prepackaged and designed grouts were be prepared as control grout and micro steel fibres were incorporated into the grout mix at different volume fractions, which are 1%, %1,5, 2%, respectively. 4*4*16 cm sized prism specimens were prepared to determine flexural strength, compressive strength after the flexural and modulus of elasticity at the 1st, 7th, 28th curing ages of the specimens to investigate mechanical properties. Micro steel fiber usage generally improved mechanical properties. 5*5*5 cm sized cube specimens were also prepared and in order to determine chemical resistance, the specimens were immersed different acid environments after 28 curing ages of the specimens. After that, mass change of grout cubes were followed at 1, 2, 4, and 8 weeks of age and residual compressive strength before and after acidic environment. The prism grout specimens were applied freze-thaw test according to standarts for examining environmental affects. Prism grout specimens after 28 curing ages were applied capillary water absorption test. The present test results verified that the micro steel fiber reinforced grouts had superior durability characteristics. According to the results which obtaine in these studies, mechanical and durability properties of cement based grouts were improved by determining optimum dosage of steel fiber additives and by analyzing different curing conditions.