PSI - Issue 64

Francisco Játiva et al. / Procedia Structural Integrity 64 (2024) 1468–1475 Jativa et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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allowable ASTM C33-18 limits. Materials with sieve sizes #100 and #200 exceed the limits and are present in greater quantities. Recycled aggregates have an absorption of 6%, an average density of 2362 kg/m³, and negligible ASR potential (0.05% <0.1% length change). According to DIN EN 12620:2002 (DIN-Normenausschuss Bauwesen (NABau), 2002) water absorption should be measured after 10 minutes of storing the aggregates under water. In this study, ASTM C127/C128 was considered (as ASTM standards are commonly used in Ecuador), so results may vary compared to this guideline. Freeze and thaw specifications are not considered due to Ecuador’s lack of subzero weather. 3.2. Compressive Strength Compressive strength tests were performed on specimens made with either control or recycled aggregates. No partial replacement between control and recycled aggregates was considered in this study. Specimens were tested after 28 days under standard water cured condition (23 o C). No further compressive strength testing was done after 28 days since the aim for this test was to determine the difference between control and recycled aggregates after most of the compressive strength has been acquired. It is observed that over all there is a 35% reduction in compressive strength between control and recycled aggregate specimens, see Fig. 2a. The differences in concrete compressive strength between specimens with the different types of fibers is limited. Table 1. Recycled aggregate characterization . Recycled Aggregates 1. Density and Absorption of Recycled Aggregates , ASTM C128-22/C127-15 (ASTM, 2022b; ASTM, 2015a) Density (SSD) Absorption Density (SSD), Stone#57 2388 kg/m 3 Absorption, Stone #57 4.5 % Density (SSD), Stone#7 2370 kg/m 3 Absorption, Stone #7 5.1 % Density (SSD), Sand 2330 kg/m 3 Absorption, Sand 6.3 % 2. Dry Rodded Unit Weight (ASTM C29-23 (ASTM, 2023b)) Loose Bulk density Bulk Density Stone #57 1150.9 kg/m 3 Stone #57 1318.8 kg/m 3 Stone #7 1259.5 kg/m 3 Stone #7 1397.7 kg/m 3 Sand 1260.5 kg/m 3 Sand 1456.6 kg/m 3 3. Materials Finer than 75-um (No. 200) Sieve in Mineral Aggregate Washing (ASTM C117-17 (ASTM, 2017)) Passing Sieve #200 (%) Stone #57 2.3 % Stone #7 6.6 % Sand 22.8 % 4. Abrasion and Uniformity results of small coarse aggregates (ASTM C131-20 (ASTM, 2020)), Gradation Type 'A' Stone#57 10 % Loss at 100 Rev/ 31 % Loss at 500 Rev/ 0.33 Uniformity Stone#7 11 % Loss at 100 Rev/ 34 % Loss at 500 Rev/ 0.31 Uniformity 5. Alkali-Silica reaction (ASTM C1260-23 (ASTM, 2023c)) Length Change (%), After 16 Days Allowable limit (ASTM C1260) Recycled Sand: 0.049% 0.1% 6. Clay Lumps and Friable Particles in Aggregates Recycled Sand Clay (%) 0.72 Stone No.: #57, #7 and Sand Type: