| As a kind of new wall mater ial of foam concrete, With low density, high insulation performance and good seismic performance and other characteristics, But it was into some problems that can't be avoided. Such as low strength, that make it difficult to meet the application requirement of the wall, and because of the foam concrete shrinkage, dry wet circulation and porous structure, the wall was cracking, As well as the collapse of the wall and so on. Based on the present situation, the research is carried out in two directions on the volume stability and mechanical properties of foam concrete, The main contents are as follows:(1) In order to explore the settlement characteristics of foamed concrete, it was examined that the effect of paste viscosity and lightweight material particle size on the settlement distance, pore structure and density distribution of the foam concrete pouring height 1m slurry. And the settlement mechanism of slurry discussed. The 700 class of foam concrete was used for cast-insitu wall, When water binder ratio 0.36, reducing agent dosage 0.8%, slurry has the best stability. When condensation 12 h after pouring height of 1m, the slurry settling is 6mm, and the material distribution of that is uniform.(2) By single factor method, from five aspects of light-weight aggregate, fibers and polymers, the curing environment and its bulk density, it was carried out the research on drying shrinkage on 700 class of foam concrete. The study showed that when the aggregate volume content 15%, the content of fiber 0.10% and reducing agent dosage 1%, the shrinkage and mechanical properties of the single factor experiment of foam concrete was optimal, its drying shrinkage value of 90 d respectively is 1587×10-6, 1569×10-6and 1371×10-6. 90 d dry shrinkage value of foam concrete from 1100 to 300 level of each unit weight is in the range of 1421×10-6~2612×10-6. Based on single factor experiment, orthogonal test of 700 class of foam concrete was carried out that designed of four factors three levels. And its Optimal combination is of ceramsite 15%, fiber 0.12%, water reducer 1.2%, EPS particle 7%. By using SEM observing the concrete products, morphology and interfacial bond ing, combined with drying shrinkage data, it was analyzed the microscopic mechanism of drying shrinkage.(3) Took the ceramic, EPS particles, polypropylene fiber, water reducer and emulsion powder as the single factor variables, it was tested the compressive strength of the 700 stage foam concrete and observed the inner product and the shape of the concrete. The result of experiments showed that the 5% volume dosage of EPS, the compressive strength strength of 28 and 60 days are respectively 3.34 MPa, 3.92 MPa, 0.1% volume fraction of fiber for respectively 3.12 MPa, 3.68 MPa, 1.2% of water reducer for respectively 3.06 MPa,3.57 MPa. Based on single factor experiment research, the 700 grade and 1100 grade of foam concrete were carried out that respectively designed of four factors three levels and three factors three levels Experiment on compressive strength. The optimal combination of 700 grade and 1100 grade were ceramsite 15%, fiber 0.08%, water reducer 1.0%, EPS particle 7%,and fiber 0.12%, water binder ratio 0.42, sand binder ratio 15%. By observing the phenomenon of the destruction of foam concrete on compressive test, analyzing the characteristic of internal stress transfer, it was established that the physical model of the compression failure of the foam concrete and The physical model of the compression failure of the foam concrete is established, and analyzed the development characteristics of the compression fracture.(4) Based on the test results of shrinkage performance, by means of statistical mathematics identifying the quantitative relationship between the reference state and the influencing factors, it was established that multi-mater ial admixing shrinkage prediction model of foam concrete and was verified the validity of the model by using the test results, and was in good accord prediction. |
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