An Experimental Study on Mitigating Alkali Silica Reaction by Using Fly Ash (FA) in Combination with Silica Fume and Expanded Perlite Powder (EPP)
ASR suppression by FA, SF, EPP, FA in combination with SF and EPP were evaluated by both mortar bar and concrete prism test. Mortar bars were made based on JIS A 1146, meanwhile concrete prism bars were casted in accordance with Rilem AAR-3. Both specimens were stored in 40°C 100% R.H. controlled room. Mortar and concrete mixtures used reactive aggregate in pessimum proportion. The results indicated that FA in combination with SF and EPP showed smaller expansion compared to FA. The best of concrete mixtures in reducing expansion is combination of FA with SF (FA15SF10).
The ASR mechanism of reactive aggregates in concrete and its mitigation by fly ash: A critical review
Abstract Alkali-silica reaction (ASR) of reactive aggregates is a major durability concern of concrete. The use of fly ash as a supplementary cementing material (SCM) shows a reliable way to control ASR expansion. This paper investigates the recent findings on effects of coal fly ash as a SCM on ASR of reactive aggregates. ASR is the reaction of amorphous silica of aggregates with highly alkaline pore solution in the binder matrix producing an expansive gel. The use of fly ash as cement replacement reduces pH of the pore solution by alkali binding and thus reduces the aggregate dissolution rate and swelling pressure of the ASR gel. The efficiency of fly ash primarily depends on its chemical composition with low calcium fly ash being more effective in mitigation of ASR expansion. Based on the available literature, this paper also analyses the ASR mitigation mechanisms of fly ash and provides some recommendations for future research. The degree of aggregate reactivity measurement, effect of alumina in fly ash, swelling properties of ASR gel in presence of fly ash and the long-term alkali contribution of fly ash on ASR are of particular importance.
Simulating the Illuminance and Efficiency of the LEDs Used in General Household Lighting
Abstract The advantage of the LEDs illumination in general household lighting was proposed. High efficiency white LED as the light source was provided the energy saving illumination of the general household lightings. Different spaces in general household with different standards of average illuminance were designed and simulated by LightTools and DIALux software. The power consumptions and efficiency of traditional illuminated light sources and LED light source in lighting the household environment were analyzed and compared with each other at the same standard of average illuminance. Finally, it provided the advantage of using white LEDs in different spaces of the general household lighting.