Experimental and analytical studies on lateral pressures imposed by high fluidity concrete on stay-in-place forms

Abstract

The implementation of stay-in-place formwork has increasingly been a popular technique for casting concrete structures, offering benefits in construction scheduling and labour reduction. Stay-in-place formwork fabricated by construction materials such as fibre cement sheets and steel studs has demonstrated to supplement reinforcement in concrete elements. AFS-Logicwall formwork is a proprietary stay-in-place system for casting concrete elements applicable for external and internal walls. It consists of lightweight panels created by bonding hard-wearing fibre cement sheets to galvanised steel stud frames. These frames have perforation through the webs for placement of horizontal reinforcement and for a smooth steady movement of concrete between stud lines. However, the studs impose an additional formwork internal congestion in which the conventional concrete with nominal slumps between 65mm to 115mm may not flow easily during placement and it can set rapidly prior to "proper placement, thereby, causing honeycombing in concrete. Thus, more flowable concrete is required to perform its intended use. The concrete with low yield stress and plastic viscosity, proving the features of high fluidity and passing ability can flow laterally and vertically into the forms and through the congested stud lines and reinforcements. Nevertheless, the low yield stress and plastic viscosity characteristics of the concrete result in higher outward pressure exerted on the AFS-Logicwall formworks. Moreover, free fall of fresh concrete is normally allowed for the concrete casting operations using AFS-Logicwall forms. This may intensify the concrete outward pressure exerted on AFS-Logicwall forms, as the dynamic impact load resulted from sudden change in the chunk of concrete momentum is imparted to the forms as well. The objective of this research project is to capture the developed pressure resulted from the free fall placement of high fluidity concrete on the AFS-Logicwall formwork system using experimental investigations and to compare the results with those obtained from code-oriented empirical formulae. The experimental test program is developed to measure the magnitude and height-wise distribution of high fluidity concrete pressure on AFS-Logicwall forms. The utility of available analytical predictive equations is investigated to estimate the magnitude and height-wise profile of lateral pressure developed on the forms.

Date of Award	2023
Original language	English