| Author: | Zhang, Zihan |
| Title: | Sustainable construction using wood waste gasification biochar in reactive MgO and Portland cement composites with carbon dioxide curing |
| Advisors: | Tsang, C. W. Daniel (CEE) |
| Degree: | M.Sc. |
| Year: | 2020 |
| Subject: | Biochar Cement Portland cement -- Additives Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Civil and Environmental Engineering |
| Pages: | xii, 80 pages : color illustrations |
| Language: | English |
| Abstract: | This research aimed at exploring effect of three cement systems of OPC, MgO and OM with addition of two types of gasification biochar (2wt % of 100% air gasification and 85% air +15% CO₂ gasification respectively) and adopted two curing methods of 28-d air curing and 1-d CO₂ curing + 6-d air curing to compare internal chemical changes and effect of compressive strength in the three groups of mixing cement composites. The results mainly indicated that firstly, three groups of cement composites with two types of biochar addition under 28-d air curing are beneficial to the increase of hydrates and compressive strength, among which the three groups of samples with CO₂ BC addition have significant improvement of compressive strength. Secondly, the compressive strength of the three groups of samples with biochar addition under 1-d CO₂ curing + 6-d air curing were higher than that of cement composites under 28-d air curing. Thirdly, OPC and OM groups with two biochar addition under 1-d CO₂ curing + 6-d air curing reduced the production of hydrates and increased the production of carbonates, but the compressive strength decreased slightly compared with these two control groups, while the samples with Air BC showed the significant decrease of compressive strength. In addition, the MgO groups with two types of biochar addition increased the production of HMCs and reduced the production of Mg(OH)₂ and MgCO₃ and the compressive strength decreased compared with the MgO control group among which samples with CO₂ BC decreased compressive strength significantly. Therefore, it is recommended that 2 wt% of biochar addition into the three cement systems with 28-d air curing promoted the generation of cement hydrates and increased the compressive strength of the three cement systems composites. On the other hand, under the effect of 1-d CO₂ curing + 6-d air curing conditions, these three cement system with addition of biochar may have a few negative impact on the compressive strength, so it should be noticed this decrease under these conditions. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5320.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 2.36 MB | Adobe PDF | View/Open |
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