Lateral Pressure Test of Vertical Joint Concrete and Formwork Optimization Design for Monolithic Precast Concrete Structure

Yabin Yang,Lianchao Deng,Yungao Liu,Shunbo Zhao,Feiyang Lv,Xinxin Ding

doi:10.3390/buildings12030261

Yabin Yang, Lianchao Deng + Show 4 more

Open Access

https://doi.org/10.3390/buildings12030261

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Abstract

When the vertical joints of monolithic precast concrete structures are cast by self-compacting concrete, the design of the formwork under rational lateral pressure of self-compacting concrete becomes a key technical issue. In this paper, a prototype simulation test was conducted for the pouring of self-compacting concrete in the vertical joint of precast concrete walls. The self-compacting concrete was continuously poured from the top of vertical joints with a height of 2.8 m without any assistance such as a delivery tube. The formwork pressure of self-compacting concrete was measured at different heights with varying casting time. Results showed that the lateral pressure increased with the increase in slump-flow of fresh self-compacting concrete, reaching a peak value of about 70 kPa at a height of about 600 mm from the bottom of formwork. Compared to the concrete with a slump-flow of 550 mm, the self-compacting concrete with the slump-flow reached 655 mm and 755 mm, presenting an increase in the peak lateral pressure by 31.5% and 44.9%, respectively. A method for calculating the lateral pressure of self-compacting concrete on the joint formwork is proposed using the analysis of enveloped test curves. Under the condition with enough strength and limited deformation of the joint formwork, the optimal design of aluminum alloy formwork is determined using finite element analysis. This provides a sci-tech foundation of the optimal design to lighten the weight of joint formwork to improve the installation efficiency and reduce the manual power cost.

Highlights

Self-compacting concrete (SCC) is a high-performance concrete with high flowability, homogeneity, and stability, which flows and fills the formwork through self-weight without the help of any vibration [1]
The pressure of fresh self-compacting concrete onbeing the vertical joint of formwork
(2) The lateral pressure grade of self-compacting concrete.reaches a peak value at a featured height at the bottom of formwork, and it tends linearly decrease above this height

Summary

Introduction

Self-compacting concrete (SCC) is a high-performance concrete with high flowability, homogeneity, and stability, which flows and fills the formwork through self-weight without the help of any vibration [1]. Compared to a fresh mix of conventional vibrated concrete, SCC has an obviously increased flowability which can even reach the rheological behavior of viscous liquid. The lateral pressure of fresh SCC on formwork will be higher than that of conventional vibrated concrete, as it is increased with the flowability of fresh concrete [1,2]. A higher lateral pressure on the formwork by the SCC results from the increase in binder content and the increased replacement of Portland cement with a rational percentage of limestone powder and fly ash, due to the increases in slump-flow and the decrease in dynamic yield stress of fresh SCC [3,4].The lateral pressure can be reduced by admixing a small content of processed clay, metakaolin, and purified wet-processed attapulgite clay composed of magnesium aluminosilicate, due to their effective enhancement of the shear resistance of fresh SCC [5]. The lateral pressure can be reduced with the incorporation of fly ash in some conditions [6,7]

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Conclusion