低温下HCSA膨胀剂膨胀特性研究材料工程专业论文.docxVIP

哈尔滨工业大学工程硕士学位论文 哈尔滨工业大学工程硕士学位论文 - - PAGE VII - Abstract With the rapid development of the winter construction, the strength property, expansion property and their relationship of expansive concrete under low temperature also comes to draw peoples attentions for it has close relationship with the practical load and safety status of the structure under the low temperature. Systematically research on cement mortar adding just HCSA expansive agent after cured at 20℃、5℃、0℃、-5℃, the influence on the mechanical property, expansive property and developing compatibility of strength is invested when considering adding compound HCSA expansive agent and chemical admixtures such as NaNO2 、 NaCl 、 Na2SO4 、 FN. Making full use of the modern analysis manner such as XRD and SEM, the hydrating mechanism of gel material and microstructure of harden mortar of gel material are deeply investigated. Based on orthogonal experimental approach, low-temperature composite functional admixture was manufactured, which has more property and orientation in the northern region. Results show that, with the increase of HCSA expansive agent the compressive strength decreases while the restrained expansive ratio increases at any temperature, with the decrease of temperature the restrained expansive ratio and compressive strength decrease. In a set range of mixing quantity, admixtures with early-strengthening and antifreeze components promote the expansion performance of HCSA at low and negative temperature, HCSA-compound inorganic salt can normally hydrate and harden. In this condition, the expansive concrete can exhibit its normal strength and expansion, and these properties can develop in phase. It is proved that HCSA-compound inorganic salt can prompt pore tiny and increase AFt phase. Through orthogonal experiment, we found the best proportioning of Low-temperature Expansive is mingled HCSA with NaNO2 (0.5%), NaCl(1.5%), Na2SO4(2.0%), FN(0.1%). Keywords Low temperature; Restrained expansive ratio;