Mechanical properties of concrete with substitution of coated styrofoam balls on coarse aggregate

Bernardinus Herbudiman,Erma Desmaliana,Andhi Muhammad Irawan,M Olivia,D Andrio,G Wibisono,G Pringgana,I.M Agus Ariawan,A Marto,E Saputra,M Infantri Yekti,K Yamamoto,D Wishart,I.D Ketut Sudarsana,R Ridwan

doi:10.1051/matecconf/201927601028

Abstract

Substitution of Styrofoam balls on coarse aggregates reduced concrete self-weight. Coating on Styrofoam ball surface makes ball has shell on its surface and could increase the adhesive strength between ball surfaces and cement paste. The coating materials made by mixing of Portland cement and RCC-15 (Residual Catalytic Cracker-15) as pozzolanic material. 20 mm diameter Styrofoam balls are used. Coarse aggregates substituted by 5%, 15%, and 20% Styrofoam balls. The test specimens used three 10x20cm cylinders for each variant. Beam specimens of 15x15x60cm used for bending strength test by third point loading method. The testing of mechanical properties were 7, 14, and 28 days compressive strengths, 28 days split-tensile strengths and 28 days flexural strengths. The experimental results of concrete with various Styrofoam ball substitutions of 5%, 15%, and 20% at 28 days show the average compressive strengths are 27.6 MPa, 24.3 MPa, and 20.3 MPa, the splittensile strengths are 2.5 MPa, 2.2 MPa, and 1.7 MPa, and the flexural strengths are 5 MPa, 4.5 MPa, and 3.8 MPa, respectively. The compression strength could be predicted by density ratio method and air content method. The experimental results show that all of the variants of Styrofoam ball coarse aggregates concrete are adequate to achieve structural strength, and have nearly compressive strengths compared with the prediction by density ratio method and air content method. Styrofoam balls substitution content could be increased to make the concrete density below 1,900 kg/m3 and compressive strength above 17.5 MPa to reach structural lightweight concrete performance.

Highlights

The density of normal concrete of 2,200-2,500 kg/m3 make the self-weight of the concretebased structural element is rather high
Strength development of compressive strength in coated styrofoam balls concrete shows a similar trend as compressive strength of normal concrete so the predicted compressive https://doi.org/10.10 51/matecconf /201927601028 strength of coated styrofoam balls concrete could refer to strength development of compressive strength in normal concrete
The predicted compressive strength with density ratio approaches the result of experimental compressive strength, so the density ratio method is worth recommended to predict the compressive strength of coated Styrofoam balls concrete

Summary

Introduction

The density of normal concrete of 2,200-2,500 kg/m3 make the self-weight of the concretebased structural element is rather high. Recent concrete technology develop concrete with has less density to generate semi-lightweight (less than 2,200 kg/m3) and lightweight (less than 1,900 kg/m3) concretes. Semi-lightweight and lightweight concretes are designed to achieve the compressive strength as strong as the normal concrete. On the mix https://doi.org/10.10 51/matecconf /201927601028 design, material with very-low unit weight as styrofoam ball could be used as an alternative substitution for coarse aggregate. Lightweight concrete is concrete with lower density compared with the normal concrete. Lightweight concrete could be generated by using lightweight aggregates such as fly-ash based aggregate, styrofoam, and plastic. The lightweight aggregate has unit weight ranged 400-1,900 kg/m3 based on its strength level [1]. The lightweight concrete density ranged 600-1,600 kg/m3, and lower than 1,900 kg/m3

Methods

Results

Conclusion