The Role of Phosphorus Slag in Steam-Cured Concrete

Jin Liu,Dongmin Wang

doi:10.1155/2017/8392435

Abstract

Steam curing is an effective method to increase the hydration degree of binder containing phosphorus slag. The role of phosphorus slag in steam-cured concrete was investigated by determining the hydration heat, hydration products, nonevaporable water content, pore structure of paste, and the compressive strength and chloride ion permeability of concrete. The results show that elevated steam curing temperature does not lead to new crystalline hydration products of the composite binder containing phosphorus slag. Elevating steam curing temperature enhances the early hydration heat and nonevaporable water content of the binder containing phosphorus slag more significantly than increasing steam curing time, and it also results in higher late-age hydration degree and finer pore structure. For steam-cured concrete containing phosphorus slag, elevating curing temperature from 60°C to 80°C tends to decrease the late-age strength and increase the chloride permeability. However, at constant curing temperature of 60°C, the steam-cured concrete containing phosphorus slag can achieve satisfied demoulding strength and late-age strength and chloride permeability by extending the steam curing duration.

Highlights

With the development of the construction of concrete engineering, an increasing number of precast concrete elements are applied to modern architectures
Though elevated curing temperature tends to promote the early hydration of the composite binder containing phosphorus slag significantly, the concrete containing phosphorus slag cannot achieve similar demoulding strength with the plain cement concrete in the case of the same steam curing temperature and duration time
The demoulding strength results indicate that elevated steam curing temperature is more effective than extended steam curing duration, which is consistent with the trends of hydration heat results and nonevaporable water content results

Summary

Introduction

With the development of the construction of concrete engineering, an increasing number of precast concrete elements are applied to modern architectures. Steam curing is the most popular method in the production of precast concrete elements, which makes great contribution to construction industrialization [5, 6]. The pressure of steam curing includes high pressure, normal atmospheric pressure, and no pressure [7]. Steam curing with normal atmospheric pressure is widely used. Presetting period, heating up period, constant temperature period, and cooling period constitute a steam curing process [8, 9]. It is notable that steam-cured concrete normally has a high permeability and a low strength gain rate at late ages due to the nonuniformly distributed hydration products and loose pore structure of paste caused by high curing temperature [15,16,17,18]

Methods

Results

Conclusion