生物质秸秆灰活性分析及对混凝土力学特性的影响

为评估生物质秸秆灰作为混凝土掺合料时的活性及适用性,分析了直燃获得的生物质秸秆灰的总成分、活性成分、物相、颗粒粒度及烧失量对混凝土力学性能的影响。试验选取4种直燃后的灰样(小麦秸秆灰(WSA)、高粱秸秆灰(SHSA)、水稻秸秆灰(RSA)和大豆秸秆灰(SBSA))进行试验。采用X射线衍射分析(XRD)进行物相分析,采用X射线荧光光谱法(XRF)检测4种秸秆灰的元素组成及含量,根据相应标准检测混凝土的力学特性。研究表明:高粱秸秆灰含有27.79%的活性SiO_2+Al_2O_3总成分和73.94%的SiO_2+Al_2O_3总成分,满足ASTM对F级火山灰材料的规定,其具有4种生物质灰中最高的活性成分和总成分。当高粱灰作为掺合料时,试样7 d抗压强度较对照组强1.5%,而28 d的强度损失为1.2%,这表明未经预处理的直燃高粱秸秆灰作为是4种生物质灰中最优良的掺合料。研究还发现,活性成分和总成分与抗压强度呈正相关,而烧失量呈负相关。

Activity analysis of biomass straw ash and its effect on mechanical properties of concrete

In order to assess the activity and application potential of biomass straw ash(BSA)as concrete admixtures,it was analyzed and evaluated for some factors influenced on the mechanical properties of concrete,which were the total composition,active component,phase analysis,particle size and loss on ignition.Four kinds of biomass samples(wheat straw ash(WSA),sorghum straw ash(SHSA),rice straw ash(RSA)and soybean straw ash(SBSA))were selected and analyzed.The phase analysis was carried out by X-ray diffraction analysis(XRD).The elemental composition and content of the four straw ash were detected by X-ray fluorescence spectrometry(XRF).The mechanical properties of the concrete were tested according to the corresponding standards.It was shown that the SHSA 73.94%SiO2+Al2O3 and 27.79%active ingredient,which meet the requirements of ASTM for Class-F pozzolanic materials.It has the highest active and total components in four kinds of biomass ash.When SHSA was used as the admixture to prepare concrete,the compressive strength of the sample at 7 days was 1.5%stronger than the control group,and the strength loss at 28 days was 1.2%weaker,indicating that the direct-fired SHSA without pretreatment was the best admixture among the four biomass ashes.It was also found that the active and total components were positively correlated with the compressive strength,while the loss on ignition was negatively correlated.