Using Fly Ash as a Partial Replacement for Fine Aggregate in Concrete and Its Effects on Concrete Properties Under Different Curing Temperatures

Abstract

A shortage of natural fine aggregates has occurred worldwide, especially due to excessive consumption of them in construction activities. For this, the availability of sustainable alternative materials for natural fine aggregate is researched. Fly ash is identified as one such material that can partially replace fine aggregate in concrete. The current study demonstrates the feasibility of using fly ash as a partial fine aggregate replacing material in concrete and its effects on the compressive strength and some significant durability properties when cured under different curing temperatures. Fine aggregate and cement were partially replaced with Class F fly ash in different percentages. The curing methods (used in this study) were isothermal heat curing at 30ºC, 50ºC, and 70ºC, and one-day accelerated heat curing. The compressive strength test, carbonation depth test, rapid chloride penetration test, and surface resistivity test were performed for concrete mixtures with different fly ash replacement levels and curing temperatures. Test results reveal that the use of fly ash as a partial fine aggregate replacing material in concrete gives higher compressive strength than that of concrete with fly ash as a partial cement replacing material at both an early age and a later age. One-day accelerated curing is the most beneficial curing method, regarding the compressive strength at all the tested ages. Moreover, concrete with fine aggregate replacement gives better results for carbonation resistance, chloride penetration resistance, and surface resistivity when compared with the control mixture and mixtures with fly ash as a partial cement replacing material.

Properties of Cement-Fly Ash Mixtures With Substandard Fly Ash as a Partial Cement and Fine Aggregate Replacement

“…The charge passed of the concrete was lower with the increase of the sand replacement percentage due to higher actual total binder content and lower actual w/b, which led to the reduction of porosity in the concrete. The better resistance to chloride ions penetration of the mixtures with sand replacement by the substandard fly ash is consistent with the findings of Papadakis [35] and Surangi et al [22].…”

“…In addition, the fly ash replacing sand also plays the role of binder in the concrete. The replacement methods used in this study were similar to those used in the studies of, Hung [19], Papadakis [20], Siddique [21] and Surangi et al [22]. There were six mixtures of the concrete tested in this study.…”

Ảnh hưởng của tro bay thay thế một phần cát tới tính chất của vữa xi măng

“…Ở một số nước, các nhà nghiên cứu cũng đã sử dụng tro bay để thay thế một phần cốt liệu nhỏ trong bê tông. Rajamane và Ambily [11] đã sử dụng tro bay thay thế cát trong bê tông. Cát có thể được thay thế lên tới 60% bởi tro bay mà không ảnh hưởng nhiều tới tính công tác và cường độ yêu cầu của bê tông.…”