Use of Off-ASTM Class F Fly Ash and Waste Limestone Powder in Mortar Mixtures Containing Waste Glass Sand

Developing sustainable concrete with less ordinary Portland cement is a growing issue in the construction industry. Incorporating industrial by-products (such as fly ash or slag) or municipal solid wastes (such as waste glass or recycled concrete aggregate) into the concrete becomes an effective way to reduce the consumption of natural sources and carbon dioxide emission if a proper mix design is provided. The present study examines the influence of the combined use of off-ASTM Class F fly ash (FFA) and waste limestone powder (LSP) on flowability, compressive strength, and expansion characteristics of mortar mixtures containing waste glass sand (WGS). FFA and LSP were used as cement replacement while WGS was used as partial reactive siliceous river sand replacement. Material variables included different WGS replacement ratios (25%, 50%, and 75%) with river sand, LSP contents (25%, 50%, and 75%), FFA contents (15%, 30%, and 45%), and different combinations of FFA-LSP (15–10%, 15–15%, 15–30%, and 15–35%). It is shown that the single use of FFA or LSP reduces both compressive strength and flowability of mortar mixture as its replacement level increases. However, mixtures combined with FFA and LSP provide higher or comparable strength to the single LSP or FFA mixture. For the expansion characteristics due to alkali-silica reaction, the single-use of more than 30% FFA or 75% LSP has less than 0.1% expansion, which is a non-reactive aggregate criterion based on the C1260/C1567 when the test period is extended to 56 days. Moreover, the combination of FFA and LSP has a considerable reduction in expansion rate compared to the single FFA or LSP mixture.

GGBS Use in Concrete as Cement Constituent: Strength Development and Sustainability Effects – Part 1

This study, third in the series, following from ground limestone and Class F fly ash, evaluates, as a cement constituent, the effect of using ground granulated blast furnace slag (GGBS) on the strength development of concrete, and consequently its embodied carbon dioxide (CO2e). The paper has been built from systematically analysing, evaluating and modelling the extensive data-matrix developed, having 85,099 data points, from the information sourced from 663 studies published in English, during 1974 to 2020, by 1,672 authors, working in 718 institutions in 49 countries, globally. It is shown that, at a given water/cement ratio, in comparison to Portland cement (PC), the use of GGBS results in a reduction in 28-day concrete strength, which increases with GGBS content, at a rate determined by the strength of concrete, GGBS fineness, and curing of concrete. It is also shown that, as to achieve a 28-day design strength, a lower water/cement ratio is required with a PC/GGBS blended cement than PC, this will reduce the actual CO2e savings that can be realised with the use of GGBS as cement constituent in manufacturing concrete. Finally, it is shown that GGBS is more effective in lowering CO2e of concrete than FA and GLS.

The Effect of Microbes and Fly Ash to Improve Concrete Performance

This paper presents the application of�fly ash�combining with microbes in concrete to reduce cement content.�A class F fly ash as cement replacementwas applied with ratios of 20%, 30%, 40%, and 50% to reduce hydration heat. Microbes from bacterial consortium were applied to as the filler to increase concrete compressive strength. The concrete mix design from SNI 03�2834�2000 was applied for a compressive strength target of 30 MPa. The mechanical test was carried out consisting compressive and tensile test.�Concrete�workability�and the heat hydration measurement were performed for fresh concrete.�The results showed that the maximum strength of 45.10 MPa was obtained from specimens with 30% fly ash content.�Application of microbes associated with�fly ash content of 40% showed the maximum strength of 48.47 MPa.�It was found that the tensile strength also increased with the application of�fly ash�and microbes.�Hydration temperature of concrete decreased with the increase of�the ash�content.�This proves that the application of�fly ash�and microbes in concrete can reduce the cement as well as increasing the concrete performance.

Effect of glass fiber and recycled aggregates on Geopolymer concrete

This study presents the effect of glass fiber and recycled aggregates on the strength properties of Geopolymer Concrete (GPC). The recycled aggregates were incorporated as a partial substitute for the natural coarse aggregates in the geopolymer concrete at 50%, 80%, and 100% by weight, and the results were compared to natural coarse aggregate. Class F fly ash is utilized as the source material for the production of Geopolymer and brought in from local sources. The effect of glass fiber (alkali resistant) with a length of 36 mm is also studied for the content ranging from 0.3, 1, 2, 3, and 3.5% based on the weight of the concrete. The flexural strength and compressive strength were compared at 7 days and 28 days for different cases. The results show that 1%, 1.5%, 2%, and 2.5% of glass fiber have exceeded the flexural strength of the geopolymer concrete by 20%.

Experimental study on Strength Attainment of concrete containing silica fume and fly ash

Increased utilization of cement in recent construction techniques leads to the global gas emission and involves high cost. Many researchers investigated the incorporation of pozzolanic materials in the cement in order to reduce its notorious effects on the environment which directed this research in order to develop high strength concrete by partially replacing supplementary cementitious materials with the cement. This study represents the experimental investigation on concrete which is blended with class F fly ash and silica fume in order to obtain high strength concrete. For this purpose, silica fume is used in 6%, 9% fly ash is replaced with 30%,40% and 50% by weight of cement. The specimens were subjected to curing up to 90 days and conducted tests in order to determine the mechanical properties like compressive strength, flexural strength and durability properties like RCPT and UPV. Based on the experimental results, addition of 6% silica fume and fly ash at 30% replacement is high strength attainment as well as durability in the concrete.

Crack formation behavior of composite fly ash – bentonite (FAB) in landfill liner system

This study aims to investigate the influence of different mixtures on the phenomenon of desiccation cracking in bentonite-fly ash mixtures as a landfill liner system. Fly ash is quite potential to be used as a landfill liner mixture because it has a low hydraulic permeability or conductivity value. This study uses class F fly ash from the Paiton power plant production process, Indonesia, which has been distributed commercially. Desiccation test was conducted in this study. The composition of fly ash and bentonite which is used are pure fly ash (FAB0), fly ash and bentonite 15% (FAB15), fly ash and bentonite 20% (FAB20) and fly ash and bentonite 25% (FAB25). The smallest CIF value is found in the pure fly ash layer. However, the pure fly ash cannot be used as landfill liner because the high permeability value. Therefore, the addition of bentonite will increase the possibility of crack formation. This study reveals that the addition bentonite in the fly ash composite will increase the crack. However, determining appropriate mixture composition is critical when working on the landfill liner system.