PSI - Issue 45

Huailiang Chen et al. / Procedia Structural Integrity 45 (2023) 104–108 Huailiang Chen et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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3 Mesoscale simulation of rubberized mortar 3.1 Material properties of each phase in rubber mortar

The rubber particles in the rubber mortar are usually regarded as an elastic material that will not crack under load. The damage mainly occurs in the mortar matrix and ITZ, which is modeled by the Concrete damaged plasticity model in this work. According to Huang et al. (2015) and Xiao et al. (2013), the ratios of elastic modulus, compressive strength, and tensile strength of the ITZ on aggregates in concrete were about 70% of those of mortar matrix. In this study, the ratio 60% is used for conservative simulation. The material properties of ordinary mortar were obtained through experimental tests, i.e. , 22836 MPa (Young’s modulus), 60.15 MPa (compresion) and 3.58MPa (tension) . Material properties of rubber particale were obtained from the study of Duarte et al. (2015). 3.2 Compressive strength simulation In the proposed model, a rectangular steel plate with a size of 90*10mm is installed on both ends of the model (see Fig.1). The midpoint of the top surface of the upper steel plate and the midpoint of the bottom surface of the lower steel plate is chosen as reference points and named RP-1 and RP-2. A vertical displacement is applied at RP-1 and constraints are applied at RP-2. Rigid body constraints are adopted to define the constraint between the reference point and its attached steel plate. The interaction between both the upper and lower ends of the specimen is designated as surface-to-surface contact. Hard contact is set to the normal orientation. The reaction force at RP-1 is used to calculate the compressive strength of CRM specimens.

Applied load(mm)

Upper steel plate

RP-1

CRM sample

H

RP-2

Lower steel plate

Fig. 1 Schematic diagram of CRM specimen.

3.3 Application and validation of mesoscale models Because Young’s modulus of rubber is only ~0.01% of that of mortar, rubber particles can be considered as pores. The results for CRM samples containing circle-derived polygonal rubber particles and reference samples with the same number of pores indicated that the error caused by equating rubber particles to pores is negligible. Six pore-based CRM models with different rubber particle distributions are created for the rubberized mortar with each mix code, including CRM6, CRM12, and CRM18. The average compressive strength of the six models obtained by ABAQUS analysis is set as the calculated results of the rubber mortar. Previous research reported that the incorporation of rubber particles increased the porosity of the mortar(Onuaguluchi & Panesar 2014, Uygunoğlu & Topçu 2010, Zhu, Thong-On & Zhang 2002, Turki et al. 2009). Turgut & Yesilata (2008) prepared mortar bricks mixed with 10%-70% crumb rubber particles, by sand volume. The test results indicated the porosity increases with the increase of rubber content, and the increment in porosity of bricks with 10% and 70% rubber content was 21.21% and 73.73%, respectively. Based on the numerical simulation results, a fitted formula can be obtained to predict the strength reduction rate of CRM as shown in Eq. (1). = −920.75( +Δ ) 3 + 166.75( +Δ ) 2 − 12.497( +Δ )+1 (1 )