粉煤灰矿渣掺量对劣级配砂配制混凝土性能的影响

摘要

为生产优质的劣级配砂配制混凝土，通过调节粉煤灰矿渣掺量配制了6组劣级配砂配制混凝土，用Andreasen方程评价砂石堆积效应，并测试混凝土坍落度和抗压强度，研究粉煤灰矿渣掺量差异对劣级配砂配制混凝土工作性和抗压强度的影响。研究结果发现，劣级配砂与石混合仍可获得较紧密堆积，复掺40％粉煤灰、矿渣的混凝土及单掺30％粉煤灰的混凝土工作性满足泵送要求；各组混凝土56 d抗压强度均满足强度等级要求，且随粉煤灰含量增加混凝土抗压强度减小。可推断矿渣粉煤灰掺量对虽为劣级配砂配制但具有较紧密堆积混凝土工作性和抗压强度的影响，与对正常级配砂配制混凝土工作性和抗压强度的影响一致。%In order to fabricate high quality concrete using poorly graded sand,six groups of concrete with poor sand gradation were prepared with different dosages of fly ash (FA)and blast furnace slag (BFS). The sand and stone compactness of the concrete was evaluated using the Andreasen equation, and the slump and compressive strength of the concrete were tested to study the effect of the dosage of fly ash and blast furnace slag on the workability and compressive strength of the concrete prepared with poor sand gradation. The results showed that the poorly graded sand and crushed stones had an adequately dense packing;both the concrete groups with 40% FA +BFS replacement and 30% FA replacement satisfied the pumping requirement;the concrete compressive strength in each group at 56 d satisfied the requirement of the strength grade,and decreased with the increasing of the dosage of fly ash. Therefore,the effect of the FA and BFS dosage on the workability and compressive strength of the concrete with poor sand gradation and dense packing is similar to that on the concrete with normal sand gradation.