Effect of Rice Husk Ash and Fly Ash on the workability of concrete mixture in the High-Rise Construction

Lam Van Tang,Anh Ngoc Pham,Tho Dinh Vu,Sofia Bazhenova,Olga Aleksandrova,Boris Bulgakov,D Safarik,V Murgul,Y Tabunschikov

doi:10.1051/e3sconf/20183302029

Abstract

The dense development of high-rise construction in urban areas requires a creation of new concretes with essential properties and innovative technologies for preparing concrete mixtures. Besides, it is necessary to develop new ways of presenting concrete mixture and keeping their mobility. This research uses the mathematical method of two-factors rotatable central compositional planning to imitate the effect of amount of rice husk (RHA) and fly ash of thermal power plants (FA) on the workability of high-mobility concrete mixtures. The results of this study displays regression equation of the second order dependence of the objective functions - slump cone and loss of concrete mixture mobility due to the input factors - the amounts RHA (x1) and FA (x2), as well as the surface expression image of these regression equations. An analysis of the regression equations also shows that the amount of RHA and FA had a significant influence on the concrete mixtures mobility. In fact, the particles of RHA and FA will play the role as peculiar "sliding bearings" between the grains of cement leading to the dispersion of cement in the concrete mixture. Therefore, it is possible to regulate the concrete mixture mobility when transporting fresh concrete to the formwork during the high-rise buildings construction in the hot and humid climate of Vietnam. Although the average value of slump test of freshly mixed concrete, measured 60 minutes later after the mixing completion, decreased from 18.2 to 10.52 cm, this value still remained within the allowable range to maintain the mixing and and the delivery of concrete mixture by pumping.

Highlights

Modern architecture and construction would hardly be possible without the use of concrete
This paper mainly focuses on the effects of rice husk ash and fly ash from TPP “Vung Ang” on the working ability of the concrete mixture and its loss for different time periods by the form of second-order regression equations
Correlation analysis made it possible to establish the mathematical dependence of standard slump cone of high-mobility concrete mixtures, which was measured at different time intervals after completion of mixing of raw materials, on the amount of rice husk ash (RHA) and Fly Ash (FA) of TPP “Vung Ang” by using Central composite rotatable design (CCRD) method for two factors [20 - 22]

Summary

Introduction

Modern architecture and construction would hardly be possible without the use of concrete. - Using separate stationary equipment for high-rise buildings and structures construction: the receiving bunker and concrete pump are located on the ground; the boom-crane with an autonomous drive is installed on the working horizon and shifted upwards during the construction as required. The advantages of the pneumatic method in feeding a concrete mixture are high productivity, unused cranes and the possible application at any point. This method’s disadvantages are the limitations on the parameters of the mixture and the size of the aggregate (less than 40 mm), as well as the high costs to flush the pipelines. This paper mainly focuses on the effects of rice husk ash and fly ash from TPP “Vung Ang” on the working ability of the concrete mixture and its loss for different time periods by the form of second-order regression equations

Materials

Methods

Results and discussion

Conclusions