Effect of natural pozzolan on strength and temperature distribution of heavyweight concrete at early ages

Abstract

The benefits of using mineral additive as a partial replacement for cement in heavyweight concrete are discussed. This paper presents the strength development and temperature distribution of concrete using Class F of natural pozzolan (PU) sourced from Northern part of Vietnam. Based on the results of conducted studies, strengths of the natural pozzolan concrete at different ages were generally lower than those of control concrete. The 7-day compressive strengths of concrete with 20% PU decreases mostly by 30.1% and least by 12.3% at the age of 28 days in comparison with control concrete. However, natural pozzolan increases the workability of fresh concrete up to 16.67% in comparison with control concrete. By using the computer program Midas Civil, the maximum temperatures at the center of concrete block with 100% cement and of concrete block with 80% cement + 20% PU are 65.7600C and 52.4400C, respectively, after 48 hours from the beginning of pouring. In addition, temperature difference between the central point and the environmental temperature of the control concrete are higher than heavyweight concrete using 20% PU. Meaningfully, the risk of through thermal cracking of heavyweight concrete without pozzolan are higher than heavyweight concrete PU to replace 20% of mass cement.

Combined Effects of Bottom Ash and Expanded Polystyrene on Light-weight Concrete Properties

“…Besides that, the annual amount of industrial waste is more than 150 million tons in Vietnam. In which, metallurgical slag is about 45 ÷ 55 million tons, ash and slag TPP is nearly 50 ÷ 60 million tons [8,9]. In 2016, TPP "Vung Ang" produces about 3000 tons of ash and slag waste daily.…”

Value Engineering Fly Ash Optimu Analysis Value Engineering Fly Ash Optimum for Mass Concrete

“…In the BAPPENAS report, Indonesia has fly ash from burning coal in the abundant power plant, in the period 2016 to 2019, coal demand in 2016 was 86.7 million tons, in 2017 amounted to 88.4 million tons, in 2018 it increased to 107.2 million tons and in 2019 it will be 166 million tons. And also based on previous research, concrete composition of 100% cement compared to the composition of 80% cement + 20% fly ash, the peak temperature of concrete using 100% cement is 65,76 0 C, while using fly ash, the peak temperature of concrete is 52,44 0 C (Tang, et al, 2018).…”

Combined effect of limestone fine aggregate and pozzolan on properties of high performance fine-grained concrete

“…This increase in compressive and flexural strength is attributed to the increase in surface area of the LFA requiring more cement paste to coat the particles surface of this aggregate. Moreover, this increment in the strength may be due to that the amorphous silica dioxide (SiO2) in FLA (of 6.01%) and in PU (of 49.8%) can react with Ca(OH)2 (calcium hydroxide) in the micro-structure of concrete to form gels secondary calcium-silicatehydrate (C-S-H) and make it more than C-S-H gels and its structurally dense as also the results of published studies [20][21][22][23][24].…”