Mechanism Of Drinking Water | Research Proposal
The mechanism of drinking water treatment sludge for mitigating the Alkali-Silica reaction in cement composite
Introduction
The purpose of the research proposal is to deeply understand the research topic on utilizing and understanding the mechanism of drinking water treatment sludge for mitigating the Alkali-Silica reaction in cement composite. Alkali-Silica reaction is considered to be the primary issue usually seen in concrete or in the cement composite (Beglarigale & Yazici 2014). Alkali-silica reaction is also known as concrete cancer, which takes place in concrete (or in cement). It is basically a reaction of swelling that takes place inside the concrete which expands over the specific time duration, due to highly alkaline cement and reactive non-crystalline silica (Nowasell 2016). At the point when water for example, two molecule of hydrogen and one particle of oxygen absorbs, the hydroscopic gel swells and change in volume parameters takes place which expands the altered aggregates and forms soluble and viscous gel sodium silicate (Guo et al. 2018). Due to which it exerts intense pressure in siliceous aggregate and resulting into loss of concrete strength and/or also cause micro fractures which acts as cause of failure (Latifee 2016).
Not only this, there are many other several inductive agents which affects and cause the reaction responsible for the Alkali-silica reaction and needs to overcome the effect. So, it is necessary to understand the current scenario of researches in the field of civil that have been done on mitigating the Alkali-silica reaction (ASR) effects which holds the significant role towards the betterment for the society and for greener and sustainable infrastructure. To undergo the process, treatment sludge will be imported from the water treatment plant of happy valley, South Australia. And also, materials like aggregates, glass sand and paper will be used towards the mitigation process of Alkali-silica reaction (ASR) effects.
Significance of Research
Although numerous researchers have already investigated the Alkali-silica reaction and its effect of ground-granulated blast furnace slag, but the impact of supplementary cement materials on alkali-silica reaction especially in South Australia have been limited. There is also a lack of research on the information about using combination of fibers and groun-granulated blast-furnace slag (GGBS) for reducing the Alkali-silica reaction in cement. There is a role of GGBS in reducing the expansion and detrimental effects of Alkali-silica reaction in the cement so that its exposure can be reduced and cement’s quality can be enhanced (Beglarigale & Yazici 2014). Moreover, there is also a knowledge gap on the aggregation of moisture in the cement content that increases the ASR whilst reducing the quality of cement. Using the previous research on GGBS, fiber , aluminum and water treatment to control the moisture content in cement will be used for this study for improving cement quality in South Australia. Moreover, use of drinking water treatment will be tested for reducing the ASR in concrete structures in the samples obtained.
Problem Statement
There is still knowledge gap present about the mitigating process of the ASR condition as the knowledge about the actual cause of the ASR development or the alkali aggregation is still not clear among the experts. Thus, the future research focusing on this aspect should be conducted. Moreover, gas evolution and the negative effect over mechanical properties regarding the porosity of the concrete structures should also be addressed before the implementation of the alternate mitigation strategies. Many effects and variations may be observed in concrete during Alkali-silica reaction effect like cracking critical structural failure which leads to the demolition of structure. In 1930s, Thomas E Stanton studied for the very first time the expansion of concrete in California due to the reaction of cement and aggregate and later in 1940 he published the article. This reaction is due to the interaction of chemicals between alkali-hydroxides usually derived from cement and reactive particles present in aggregates. Alkali-silica reaction produces numerous chemicals known to be alkali-aggregate reactivity. The reaction generally takes in between 5-12 years but has many exceptions. The equation shown below is the idealised in form. (Hay & Ostertag 2018)
The nature of this research topic is quantitative analysis which will be carried out by integration of sludge into water that helps to counter Alkali-silica reaction (ASR) effects. The mechanical properties hence to be observed along with their variation in physical and chemical properties. Different lab work has to be done and different mortar materials needs to be tested after which the interpretation of the final sludge product will be integrated into the cement followed by the testing of strength capacity of the final cement product and also the measurement of the product obtained needs to be taken and discussion will be made based on the resulting measurement by their increasing or decreasing nature which we believe will see the effect towards the mitigation of Alkali-silica reaction (ASR). The research topic is carried out and discussed in 6 several tasks discussed below.
2. Review of Literature
2.1 Waste Aluminum for Mitigating the ASR Issue
ASR is considered to be one of the most commonly occurring issues in civil industry that can reduce the durability of the concrete structures (Hay & Ostertag 2018). Out of many ways, one main method of reducing ASR from concrete was found to be through utilization of waste aluminum in forms of powders, bit and dissolved. According to Hay & Ostertag (2018), the testing of accelerated mortar bar under reactive glass dissolution, microstructural analyses and the pore solution produced favorable results for concrete structures by reducing/mitigating the ASR effectively. The study also reported that although waste aluminum was effective in mitigating ASR, but its long term effectiveness was questioned as the control on ASR was diminished over time due to mixing of hydration products with cement in the given test. Aluminum bits and the powder were also found to be effective in this process of the mitigation of ASR issues in various amounts as well (Brykov, Anisimova & Rozenkova 2014).
Another study by Jongprateep et al. (2018) highlighted the use of aluminum for reducing the effect of ASR on concrete expansion. According to the study, ASR was found to be the main cause of expansion in cement that caused concrete structures to fall off eventually. Due to swelling in the ASR gel caused by humidity, the concrete structures can crack and the whole structure can fall as well. In this case, the study utilized aluminum powder as an air entrainment agent for reducing ASR problem in concrete. By using mortar bars with aluminum content of 0.1, 0.15, 0.2 and 0.05, the study concluded that the cement expansion was reduced more with the use of 0.2 aluminum content. Hence, it was revealed through microstructural analysis that the spaces in ASR gel were being largely accommodated with entrained pores due to aluminum while decreasing the overall concrete expansion. The results matched the conclusions made by Shi et al. (2015) who also reported improvement on controlling the overall ASR damage in concrete structures by adding higher alumina content.
2.2 Water Treatment for Improving Concrete Quality
Based on the views of Nowasell (2016, p.4), drinking water treatment is one of the common purity treatments for the cement concretes. However, it has been seen that the factor of the drinking water treatment there are several issues including the production amount and the aftermath of the treatment. On this context the author stated that the large amount of production and low amount of profit rate in this process is one of the most prominent issues.
Cao & Kevern (2011) also conducted a study on analyzing the use of drinking water treatment waste for curing the concrete issues and reported it to be an effect low-cost treatment method. The author suggested to use high water content, especially incorporated with calcium carbonate material for mixing in the concrete. Other two materials tested included prewetted superabsorbent polymer and light fine polymer. It was found out that out of the three tested materials, the cement’s compressive strength, its degree of hydration and shrinkage improved effectively by using water treatment waste method as a curing agent. It was also concluded that the autogenous shrinkage of concrete was reduced and the cement hydration improved effectively when treated with waste water.
Moreover, the drying cost and the energy production for the drying of the moisture formed due to the treatment of the water has an impact as well (Saito, Kawamura, & Arakawa 2011). On the other hand, the material character and impact of the treatment on the products also play a crucial role. Furthermore, the moisture and the drying transformation effects over the content of the concrete structure also have a great impact and it leads to the crack formation over the concrete internal structure (Benboudjema, Meftah, & Torrenti 2005). This condition leads to the requirement of the cement replacement which is a costly process and this process also time consuming as well (Xu, Galama & Sathaye 2013). On this context the study by Nowasell (2016) concluded that the drinking water treatment is one of the effective process however, the issues regarding the effects of the process would lead to the negative impact over the profit and the sustainability of the concrete structure.
2.3 Research of the Alkali-silica Reaction (ASR) Effect
As, Alkali-silica reaction (ASR) also depends on the varieties and types of aggregates that involved in the reaction which induce the Alkali-silica reaction (ASR) effect. The transition of the reaction may take up to several days depending upon the size of the aggregates and their reactivity nature towards the cause of Alkali-silica reaction (ASR) effect (Brykov, Anisimova, & Rozenkova 2014). Classification is done based on non-reactive, moderately reactive, highly reactive or very highly reactive. Which will be used to describe the mitigation level depending on the aggregate size for example, expansion is larger with larger particles and how the reaction takes place on the surface of the materials whilst few other will only react in microstructures of the same.
2.4 Fine Lightweight Aggregate for Mitigating Alkali-silica reaction (ASR)
Li (2016, p.52), highlighted that the process of mitigating ASR is one the crucial factors for the sustainability development of the concrete structure as it is an impurity and affect the structure various ways. On this context the author stated that the fine lightweight aggregate is one of the effective processes for the mitigation of the issue. On this context it has been seen that the ASTM testing method is required for the purity checkup of the structure or the cement content (Berube, Duchesne, & Chouinard 2005). Hence, the ASTM testing method included with the ASTM C289, ASTM C1260 and ASTM C1293 were chosen by Li (2016). The authors stated that the fine normal weight aggregates if replaced by the fine light weight aggregates by 25 per cent and 50 per cent in the concrete mixture and by 25 per cent, 50 per cent and 100 per cent in the mortar mixture then the ASTM C1260 and ASTM C1293 would be helpful in the calculation of mitigation efficacy of the fine lightweight aggregates. On this context it can be stated that the further research on this process should be conducted for the better assessment of the condition. Moreover, the factor of the development of the alternate processes for the mitigation of the ASR issues should be considered with priority as there are several impacts of the drinking water treatment for mitigating this issue.
