Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

Abstract

Abstract:The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties.

Enhancement of Material Properties of Lime-Activated Slag Mortar from Intensified Pozzolanic Reaction and Pore Filling Effect

“…The particle size distributions of the materials are presented in Figure 2, in terms of percentage volume density. These were determined by a laser diffraction method using Mastersizer 3000 (Malvern Instruments, Malvern, UK) for GGBFS and HL, and by an image-processing method for SF [26,27]. The laser diffraction method also provided a specific surface area of GGBFS (6.9 m 2 /g) and HL (1.3 m 2 /g).…”

“…This, in turn, can contribute greatly to improving mechanical performance and durability. In addition, the SF, which is composed of nanoparticles, if not reacted, can physically fill the capillary pores, by the pore filling effect [26,27]. In summary, the addition of SF to the LAS composites can improve their mechanical performance and durability through physical and chemical means.…”

End-of-Life Materials Used as Supplementary Cementitious Materials in the Concrete Industry

“…The American Society for Testing and Materials (ASTM) produced the initial report on standards for applying FA more than 40 years ago, ASTM C 618 [26]. SF additions to concrete improve several other physical and chemical properties besides the mechanical strength: lower adverse environmental impact, decreased permeability, increased corrosion protection for steel bars and improved resistance against the sulphate and chemicals attacks [68,69].…”

Long-term effects of waste brick powder addition in the microstructure and service properties of mortars

“…For those reasons, the research about new suitable cement additions is still the topic of many studies [7,8]. Among those additions, the study of brick powder as clinker replacement has been the topic of recent researches [9][10][11][12].…”