Reconnoitring principles and practice of Modified Andreasen and Andersen particle packing theory to augment Engineered cementitious composite
S. Indhumathi, Sanjeev Kumar, Moorthi Pichumani
Abstract
Engineered Cementitious Composites (ECC) is a heterogeneous high-performance material with improved compressive strength and fatigue resistance. The nature and intensity of packing has a significant impact on the efficiency of ECC. To streamline the mix design by an improved technique the current study focuses on employing the Modified Andreasen and Andersen (MAA) theory to optimize the mixture proportions of ECC with the particle packing concept that in turn reduces lot of trial mixes. The primary input parameters are particle size distribution, density of materials, binder proportions and water content. In this case study, about series of 6 group of trail mixes with water binder ratio ranging from 0.14 to 0.24 are chosen, and the optimization is carried out using Elkem Materials Mixture Analyser (EMMA). Hence the MAA deals with the solid particle packing effect, the ratio of water and High Range Water Reducing Admixture (HRWRA) depends on the flowability test of ECC. According to the results, the optimal dosage of HRWRA is 2.62 percent with a water binder content of 0.16. It is ascertained from the case study that, A 09 mix recipe exhibits improved compressive strength of up to 82 MPa at 28 days. Some of the mix recipes exhibit higher early strength, but the strength decreases with age in some compositions of ECC. The discontinuity of hydration process due to the presence of excessive early age additives such as silica fume, lack of adaptivity between the cement and superplasticizer, inappropriate combination of mixture proportion reduces strength of ECC.