Initial Strain of Plain Bar in Lightweight Brick as Precast Concrete Slab Pratikto , Anni Susilowati
Department of Civil Engineering, Politeknik Negeri Jakarta
Abstract
The public has a strong desire for multi-story houses, which developers are choosing to build. When compared to extensions done horizontally, the expenditure for structures expanded vertically can be smaller. The industry uses the execution of floor plate work that is lightweight and can be completed quickly. A reasonably priced and robust concrete floor slab route can be formed by stacking lightweight bricks in a precast manner. With a compressive strength of 5 MPa, lightweight concrete bricks are made of cement, fine aggregate, and foaming agents. The light bricks are 20 by 10 by 60 mm, and they are put together with plain bar P10 reinforcement at each corner and covered in concrete mortar to create a one-way slab concrete. The reinforcement is positioned in the best possible locations and covered with concrete in accordance with the 20-mm code. A hole is drilled in the middle of the cross-section to accommodate the P10 reinforcement, which is going to bear the brunt of the initial strain. A multi-story house^s floor slab is made up of multiple one-way slab strips joined together as precast concrete slabs. The strength test of this line is reviewed based on the deflection adjusted to the SNI 2847-2019 permit deflection for concrete, namely not exceeding L/360, so that for a span of 90 cm, it is found to be 25 mm. The load acting on the floor slab apart from the load itself is the live load of the residential house according to SNI 1727-2020, at least 1.92 kN/m2 or 200 kg/m2. The results of several loading tests with a pure bending moment on a span of 90 cm from two types of beams with and without initial strains were found to be 500 kgf and 270 kgf, respectively. The load resulting from a system with an initial strain can increase the load by 146%. The presence of initial strains in the cross-section can increase the ability of a series of lightweight bricks to serve as precast concrete slabs.
Keywords: initial strain, lightweight brick, grouting , pure bending moment
