The Impact of Formwork Material on the Performance of Plain Concrete

Abstract

Formwork is crucial in concrete construction, containing and supporting fresh concrete until it achieves its design strength. Proper selection of formwork is vital for ensuring high-quality concrete with desired mechanical properties. The construction industry is shifting from traditional to more innovative, economic, and sustainable formwork materials to address issues like waste, hazards, and life cycle impacts. However, there is a lack of comparative evaluations and performance-based selections of different formwork systems. This study investigates the effects of commonly used formwork materials: timber plank, steel, and marine plywood on the concrete properties. Concrete cubes with a 1:2:4 mix ratio and a 0.5 water-cement ratio were cast using steel, marine plywood, and timber plank formworks. Tests were conducted at various ages to assess the influence of formwork type on key performance indicators of hardened concrete. Results showed that steel formwork achieved the highest compressive strength of 27.56 MPa at 28 days, followed by marine plywood at 26.11 MPa. Timber plank formwork, though lower in strength, reached 18.44 MPa at 28 days, demonstrating potential in dry conditions. The use of timber plank formwork results in a significant reduction in the compressive strength of concrete, approximately 50% less compared to those cast with steel formwork.

Keywords —Steel, Timber, Marine plywood, Formwork, Concrete, Strength, Plain