68 © JOURNAL OF CIVIL ENGINEERING / Vol. 34 No. 2/ December 2019 SORPTIVITY AND CHLORIDE PENETRABILITY EVALUATION OF CONCRETE INCORPORATING FLY ASH AND SILICA FUME Wahyuniarsih Sutrisno a* , Gabriel Ghewa b , Priyo Suprobo a Abstract: Diffusion is one of the the main mechanisms of fluid ingress into the concrete. However, in partially saturated concrete, the fluid will mainly be absorbed by the capillary suction mechanism, which associates with the sorptivity properties of the concrete. This paper presents the results of an experimental program to investigate the influence of Portland cement substitution with Silica Fume (SF) and Type F Fly Ash (FA) on the rate of absorption, which also known as sorptivity, and chloride penetration of concrete. The sorptivity of the concrete was evaluated according to ASTM 1585, while the chloride penetration was evaluated according to ASTM C 1202. By substituting part of cement with FA and SF, it was found that the sorptivity of concrete is reduced. Furthermore, all type of concrete with supplementary material, including CFA, CSF and CSM, is confirmed to enhance the ability of concrete to resist chloride penetration compared yo normal concrete (NC). Keywords: Durability, Sorptivity, Chloride Penetrability, Fly Ash and Silica Fume INTRODUCTION In the recent decade, durability problems are becoming a concern to many engineer and researcher. Many constructions built in the 1900s and even the new poorly built structure is suffering to damage due to durability issues. Structures located in the area with the possibility of water intact, such as the marine environment, have a direct impact on the durability problems. In marine structure, the chloride ion is one of the main problems which can induce the corrosion problem [1]. In case corrosion induced by chloride, the passive layer of steel is damage due to chloride attack, and the corrosion process starts to develop [2], [3]. As the corrosion starts to develop, the volume of the rust will increase significantly and causing crack at the interface of the steel bar of concrete. Over time, the crack will see growth and reach the concrete surface. This condition will accelerate the chloride ingress and lead to faster development of corrosion. By looking at that fact, it is important to assess the concrete ability to resist chloride ion penetration to have a deep insight of chloride ion penetration into the concrete. The significant problems of early deterioration in the concrete structures are occurring in structures that experience frequent environmental changes, such as cyclic drying and wetting [4]–[7]. As widely known, water and oxygen are the main factors that can induce the durability problems such as corrosion. Over a certain period of time, the frequent environmental changes will lead to the fluctuation of the effective diffusion coefficient. Therefore, considering diffusion alone in the service life modeling is not sufficient for most structures, and more research is needed to incorporate other mechanisms, especially sorptivity [4]. Sorptivity is a parameter which associates with the rate of absorption of the concrete. When the concrete surface is not saturated at the specific time and it is exposed to a chloride solution, the capillary tension will absorb the water and chloride solution into the concrete. Over time, this condition will affect the pore structure of the concrete and causing durability problems. The pore structure mostly depending on the fluid penetration capacity of concrete which known as permeability [8]. Concrete with high permeability tends to absorb more water which leads to the introduction of molecules that react and destroy its chemical stability[9]. However, lower permeability of concrete can improve the durability performance of concrete by improving the penetration of water, chloride, sulfate, and other harmful substances [10]. Therefore, it is necessary to assess the fluid entrance rate into the concrete and one of the popular methods that can be used to assess this property of concrete is the rate of absorption or also known as sorptivity. Besides frequent environmental changes, another factor that can affect the rate of diffusion and absorption of the concrete is the quality of the concrete material. Several researchers found that the raw material and quality of concrete material really affect the durability of concrete [11]–[13] including the rate of diffusion and absorption of the concrete. The concrete-based on Portland cement is the most widely used material in the world. Compared to other materials like steel, aluminum and plastics, it is the most viable option for the construction industry considering economic and environmental costs. However, the production of cement is very energy-intensive and releases a significant volume of CO 2 . To overcome this problem, many researchers used supplementary material to substitute the amount of cement used for concrete. In recent years, fly ash, silica fume and blast furnace slag are the popular material for substituting cement or known as the supplementary material [10], [14]–[18]. Fly ash and silica fume are the waste product of the industrial processes. Fly ash is a by-product of coal-burning power plants and silica fume is produced by reducing the high- purity quartz with coal in electric arc furnaces in the manufactures of silicon and ferrosilicon alloys. The amount of this waste material is increasing rapidly every a Lecturer in the Civil Engineering Department, Institut Teknologi Sepuluh Nopember, ITS Campus, Sukolilo, Surabaya 60111, Indonesia. Corresponding author email address: niar1206@gmail.com b Graduate Student in the Civil Engineering Department, Institut Teknologi Sepuluh Nopember, ITS Campus, Sukolilo, Surabaya 60111, Indonesia. brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Center for Scientific Publication