Effect of Mould Size on Compressive Strength of Green Concrete Cubes

Bashir Ahmed Memon,Mahboob Oad,Sajjad Ahmed Shar,Abdul Hafeez Buller,Abdul Salam Buller,Fahad-u-Rehman Abro

doi:10.28991/cej-2019-03091322

Abstract

This paper is aimed to evaluate the effect of mould size on compressive strength of concrete cubes made with recyclable concrete aggregates. Natural coarse aggregates were replaced with 50% recycled aggregates from old demolished concrete. Five different mould sizes were used to cast 420 concrete cubes using 1:2:4 mix and 0.55 water/cement ratio. In each size equal number of cubes was cured for 3, 7, 14 and 28-day. After curing, weight of cubes was determined followed by testing for compressive strength in universal load testing machine with gradually increasing load. From the obtained results the strength correction coefficients were computed keeping 28-day cured standard size cubes as control specimens. Also, numerical expression based on regression analysis was developed to predict the compressive strength using weight of cube, area of mould and curing age as input parameter. The numerical equation predicts the compressive strength very well with maximum of 10.86% error with respect to experimental results.

Highlights

Pace of construction of high-rise buildings around the globe is increasing day by day
The compressive strength results obtained by using failure load and area of specimen in numerical expression of stress were analyzed
For this research work total of 420 concrete cubes with 50% recyclable old demolished concrete as coarse aggregate were cast using five different mould sizes to check the impact of mould size on compressive strength

Summary

Introduction

Pace of construction of high-rise buildings around the globe is increasing day by day. Construction of new high-rise buildings consumes large quantities of natural aggregates but on other hand demolishing of old or short height structures generates huge quantum of demolishing waste. Proper disposal of this waste is another serious issue around the globe due to less available space for dumping. The authors used three different sizes of cylinders (2", 3" and 4") and cubes (2", 2.78" and 4") as an alternative specimen to test ultra-high-performance concrete in the strength range of 80-200 MPa. The authors used 51 samples of each cylinder and cube. Authors observed that 3"cylinder and 2.78" and 4" cubes were acceptable as an alternative to standard cylinder specimen

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