The Mix Ratio Study of Self-Stressed Anti-Washout Underwater Concrete Used in Nondrainage Strengthening.

Shaofeng Wu,Shao-Fei Jiang,Zhaoqi Wu,Sheng Shen

doi:10.3390/ma12020324

Abstract

Anti-washout underwater concrete (AWC) is widely used in nondrainage strengthening; however, there still exist some problems with it, such as high strength loss and poor interfacial bond in practical engineering application. Based on the study of self-stressed concrete (SSC), a research on the mix ratio for the C30 self-stressed anti-washout underwater concrete (SSAWC) was carried out in this paper in hope of solving the above problems, specifically, by adding an expansive agent to the AWC. The parameters, such as strength, fluidity, anti-dispersity, and expansibility, were picked as target indices in determination of the mix ratio. The orthogonal test design and range analysis were used to determine the reasonable mix ratio and study the influence of various parameters on the performance of SSAWC. The experimental program conducted includes a series of strength, fluidity, anti-dispersity, and expansibility tests on 18 groups of specimens. The results show that C30 SSAWC has an excellent performance using the optimal mix ratio. Compared with AWC, the expansibility and self-stress of the SSAWC can be easily observed, and the compressive strength ratio of the SSAWC casted in water to that casted in air is much bigger. This implies that SSAWC is applicable to the nondrainage strengthening.

Highlights

In recent years, a growing number of in-service bridges need strengthening out of concern for both structural safety and smooth transportation [1]
Based on the studies of anti-washout underwater concrete (AWC) and stressed concrete (SSC), a series of experiments and analyses have been carried out in this study to propose the optimal mix ratio of stressed anti-washout underwater concrete (SSAWC) used in nondrainage strengthening, and reveal the effect of the designed factors on its performance, and increase the bond strength
The mix ratio of SSAWC in other strength grade can be developed using the same method as described in this paper

Summary

Introduction

A growing number of in-service bridges need strengthening out of concern for both structural safety and smooth transportation [1]. Conventional strengthening methods for the substructure, such as enlarging section method [2], bonded steel plates method [3], fiber-reinforced polymer (FRP) method [4,5,6], extraneous prestressed strengthening technique [7], and other novel methods [8,9], do improve the load capacity and durability of substructure They are more often than not expensive, time-consuming, and traffic-disrupting, because cofferdam needs to be built for drainage first before any work could be done to underwater substructures. Alternative strengthening methods that make drainage no longer necessary, such as jacket strengthening method [10], FRP underwater strengthening method [11,12], and precast concrete segment assembly method [13], have been proposed in an effort to solve the above-mentioned problems caused by drainage These strengthening methods are economical, fast, and traffic friendly compared with conventional methods. All these methods require anti-washout underwater concrete (AWC) [14], known as non-dispersible underwater

Objectives

Results

Conclusion