骨料级配对再生混凝土强度和工作性能影响的试验研究和计算分析

Experiment research and analysis of aggregate gradation on the strength and workability of recycled concrete

骨料级配是影响混凝土强度的主要因素之一。在水灰比0.55和水泥、细骨料、粗骨料的配合比为1∶2∶2.75情况下,对不同粗骨料级配情况下的再生混凝土工作性能和受压强度进行了试验测试,通过试验发现再生混凝土破坏形态和普通混凝土破坏形态相似,当混凝土工作性能有保证时,再生混凝土的强度会增大。但当混凝土工作性能没有保证或变差时,强度会降低。在不同粒径粒数分布满足分形规律和满足骨料级配的情况下,计算了包裹骨料需要的水泥浆与总水泥浆的比值γ,γ值可以反映不同骨料级配变化引起的骨料表面积的变化。γ值越大,骨料的表面积越大。γ较大时混凝土工作性能和受压强度降低。比值γ较小时混凝土工作性能和受压强度提高。中部粒径范围骨料级配的变化对再生混凝土工作性能和受压强度有明显影响。再生骨料替代率分别为50%、60%、100%时,粒径范围9.5～19mm和19～26.5mm的骨料级配接近,再生混凝土强度可以高于天然骨料的混凝土强度。再生骨料替代大粒径范围骨料的强度小于替代小粒径范围骨料的强度。

Aggregate gradation is one of the main factors that influence the concrete strength and workability.Under the condition of waterlcement ratio 0.55 and cement, fine aggregate and coarse aggregate mix ratio 1：2：2.75, the workability and compression strength of recycled concrete with different gradation is tested.It is discovered that the rupture appearance of recycled concrete is likeness to the ordinary concrete ,and the concrete strength is high when the workability of flesh concrete is good,but the strength is low when the workability is poor.The variety of middle range aggregate gradation has obvious influence on the workability and compression strength of concrete.When the recycled aggregate replacement is 50% ,60%, 100% ,and the content of aggregate particles in range 9.5-19 mm and 19-26.5 mm is near,the recycled concrete strength can be higher than the ordinary concrete.The compression strength of concrete containing bigger size recycled aggregate is higher than the strength of concrete containing smaller size recycled aggregate.On the supposition that aggregate particle number distribution satisfies fracture regulation and actual aggregate sieve gradation,the ratio y of the mortar required packaging the aggregate particle and the total mortar is calculated.The ratio y can reflect the variety of aggregate surface for the different aggregate gradation.If the ratio y is bigger;the surface area is bigger.The y value increasing means that the workability and strength lower and the y value decrease means that the workability and strength advance.