Strength Properties of Slag/Fly Ash Blends Activated with Sodium Metasilicate and Sodium Hydroxide+Silica Fume

This study presents the strength properties of alkali activated Ground Granulated Blast Furnace Slag (GGBFS) /Fly Ash (FA) blend mortars prepared with sodium meta-silicate and, sodium hydroxide-silica fume combination mixture. The GGBFS/FA ratios were arranged at (100/0, 80/20, 60/40, 40/60, 20/80, 0/100). Water to “GGBFS+FA” ratio was kept constant at 0.5. Na concentration ratio to “GGBFS+FA” was kept constant at 6%. These ratios were in mass basis. Three different mixture parameters were used. In the first series of mixture, only sodium meta-silicate was used as activator. In second and third series, sodium hydroxide and silica fume combination was used as activator. Sodium hydroxide and silica fume was mixed with water and used directly in preparation of second series of mortar mixtures. For preparation of third series of mortar mixture, sodium hydroxide and silica fume were mixed continuously with water for three days to allow dissolution of silica fume in sodium hydroxide solution. At first, 3-days compressive strengths of all alkali activated mortar mixture were measured. After that due to the very low compressive strength of mortars made with high volume fly ash content, only 100/0 and 80/20 slag/fly ash ratios were investigated for 7, 14 and 28 days compressive and 28 days flexural strength. The results of the 3 days tests show that decreasing the slag/fly ash ratio decreases distinguishably the compressive strength of the mortars. The mortars produced with the mixture of sodium hydroxide and silica fume combination as activator showed satisfactory results when compared with those activated with sodium meta-silicate

Volume 49, 2010, Number 2

In this study, the strength properties of polypropylene (PP)-fibre-reinforced fly-ash concrete were investigated experimentally and statistically. Three control factors (amount of fly ash, amount of PP fibre and curing time) were used for this study. The fly ash content that was used was 0, 60 and 120 kg/m(3) and the fibre content was 0, 0.45. 0.90 and 1.80 kg/m(3). The specimens were cured in standard curing conditions at temperature 23 +/- 2 degrees C for periods of 7, 28, 90 and 365 days. At the end of the curing period, the average of three specimens was tested to measure each of the concrete strength properties (compressive strength, flexural tensile strength and splitting tensile strength). Furthermore, the level of importance of these parameters on the strength properties was determined by rising the analysis of variance (Anova) method

The Effects of Different Types of Fly Ash on the Compressive Strength Properties of Briquettes

The aim of this study is to evaluate the effect of the different types of fly ash on the compressive strength properties of sintered briquettes. Thermal gravimetric (TG) analysis was carried out. The chemical composition and physical properties of the materials used were determined. Particle size distribution and microstructure elemental analyses of the materials used were carried out by a particle size analyzer (Mastersizer) and a scanning electron microscope (SEM-EDS). Following the characterization of the materials, briquettes were prepared by sintering at different temperatures. Compressive strength test results of the briquette samples indicated that briquettes with a compressive strength value of 47.45 N/mm2 can be produced. The results obtained exceed the Turkish standard (TS EN 771-1) requirements (9.8–23.54 N/mm2). SEM-EDS results showed that briquette samples made with Tunçbilek (T) fly ash had a higher percentage of the glassy phase than the other briquette samples. Due to this microstructure, it results in higher compressive strength value