Mechanical properties of an improved grout for cementitious precast beam-column joints

Abstract

This study proposed a new formulation for an improved grout with superior early strength and ultra-high cured strength; it was designed on the basis of the theory of closest packing. Orthogonal experiments were conducted to analyse the effects of four factors, silica powder content, water reducer content, steel fibre content, and water-cement ratio, on the flowability, compressive strength, and compactness of grout. The criteria for determining whether the grout met the requirements for Code included initial flowability greater than 300 mm, flowability more than 260 mm after 30 min, and compressive strength more than 60 MPa after 12 h of standard curing. The results showed that the performance of the grout satisfied specified requirements for Code with small internal voids and acceptable durability. After the ratio of raw materials was optimized, The grout sleeve test showed that the failure occurred in the steel bars outside the sleeve, and no grout pulling, slipping, splitting, or other behaviour occurred within the sleeve, which meant that the specimens met the design requirements. The development of this grout will greatly reduce construction time for Code and improve the quality of connections in prefabricated components. The results of this study will provide a reference for the design and development of new grouts in the future.

Keywords

• grout
• mobility
• compressive strength
• microscan
• Cl ion
• ratio optimization