The influence of nano-silica and the different pozzolan material additive on properties of high performance cement mortar

In this thesis, the effects of nano-silica and three different pozzolanic material substitutes on physical and mechanical properties were investigated. Firstly, reference samples with 100% cement content were produced as binders. Standard sand and CEM I 42.5 R type cement was used in the preparation of mortar materials. Optimization studies were carried out on standard reference samples by adding 0.25%, 0.5%, 0.75% and 1.00% by weight of nano-silica. As a result of the study, 0.50% nano-silica additive was used. Then as a substitute for mortar; the fly ash (FA), blast furnace slag (BFS) and silica fume (SD) materials were substituted separately and between 0-30% and nano-silica cement mortar samples were produced. Fly ash (FA) is obtained from Tuncbilek Power Plant (Kütahya, Turkey), Blast Furnace Slag is obtained from Bolu cement and the silica fume is obtained from the Antalya Eti Electrometallurgy. However, the treated silica (Pyrogen Silica) used in the mixtures is Wacker ™ HDK N20. The mortar samples were produced in laboratory type cement mixer. The prepared mixtures are shaped with vibration table in 4 x 4 x 16 cm metal molds. Prepared samples were allowed to set for one day. Then, the samples were cured with water for 7, 28 and 90 days. Related samples; water absorption, apparent porosity, unit volume weight and apparent density values were determined on the basis of Archimedes principle. After that, compressive and flexural strength tests (7, 28 and 90 days) of the samples were performed. According to the data obtained; It was observed that porosity and water absorption rates decreased in all samples with increasing curing time. The density values of the samples increased depending on the curing time. As a result, it was determined that the strength of the samples increased with the increase in the curing time. When the physical results of the samples are examined, nano-silica additive has positive effect on the values. Maximum pressure values of samples; It was found to be 49.2 MPa in FA substitution mortar, 66.5 MPa in SD substitute mortar and 58.5 MPa in BFS substitute mortar. In comparison with the reference mortars, it is seen that nano-silica and other filler materials give positive results in compressive strength. It is considered that silica fume with better chemical content and higher nano-silica additive will be more effective in mechanical and physical results.