Performance of nano metaclay on chloride diffusion for ultra- high performance concrete

The major cause for corrosion of steel reinforcement embedded in concrete due to chloride penetration has been the great research effort. The use of nano metaclay in UHPC increase the strength and helps the formation of micro pores by acting as a filler thus improve the chloride penetration resistance characteristic. The aim of this study is to evaluate the chloride diffusion of UHPC using RCPT and chloride penetration depth. Four (4) series of UHPC comprised of plain UHPC and a series of nanoUHPC incorporating 1%, 3% and 5% of nano metaclay were produced. It is reported that the compressive strength of nano UHPCl exhibits higher strength up to 10% compared to plain UHPC. The results showed that UHPC containing nano metaclay also significantly affect the chloride diffusion coefficient. As regards to the results, inclusion of 1% nano metaclay in UHPC led to noticeable benefit towards strength and chloride resistance

Application of response surface methodology for chloride transport properties in nano metaclayed-UHPC

The major concern on the deterioration of reinforced concrete structure is due to the corrosion of steel reinforcement from the aggressive environment such as chloride penetration. Ultra-high performance concrete (UHPC) is an advanced concrete material having ultra-high strength with excellent durability properties. Inclusion of nano metaclay in UHPC is expected to overcome the chloride transport properties in UHPC by providing nano filler effect. Two (2) assessments were conducted which are chloride content and chloride depth were examined. All the concrete specimens were immersed in 3% NaCl solution up to 365 days and the tests conducted were performed at 3, 7, 28, 56, 91, 182 and 365 days. Response surface method (RSM) was performed to evaluate the interaction and relationship between operating variables (compressive strength and nano metaclay content). Based on RSM analysis, inclusion of nano metaclay in UHPC have good relationship towards the chloride resistance characteristics and adequate durability performance in terms of chloride penetration resistance. The results exhibited that inclusion of 1% nano metaclay significantly and positively affect in term of chloride penetration resistance

Behaviour of Metakaolin Concrete in Different Curing Condition

This paper presents the result of an investigation on the effect of curing condition on concrete containing Metakaolin. Concrete grade 40 was used in this research and Metakaolin is replaced from 5%, 10% and 15%. All sample been cured by using three different curing condition which is normal curing (+20o C), expose curing (28 – 34o C) and high temperature curing (+55o ). The effect of Metakaolin on concrete will be seen by physical and mechanical properties. From physical properties the effect of Metakaolin will be seen by using soundness, setting time and workability and for mechanical properties compression and flexural test will be performed. From physical test shows Metakaolin reduce the workability of concrete and hence increase the water demand in concrete mix but the addition of Metakaolin reduce the ability of cement paste to expand. This happen because the addition of Metakaolin will fill the void around the cement paste. Results from physical test are supported by testing the mechanical part. Results show that concrete containing Metakaolin improved in all curing condition except for high temperature curing. These can be seen from compression test that shows Metakaolin increase strength of concrete except for high temperature curing. The same phenomena can be seen from flexural test. Results show the optimum replacement is at 10% and the best curing effect for Metakaolin is normal curing. Three elements that contribute to the result is the addition of Metakaolin act as a filler, accelerate the cement hydration and pozzolanic reaction that improve the physical and mechanical properties