The use of recycled aggregate in concrete can have both positive and negative effects on the compressive strength of the resulting concrete. Here are some potential effects.
Positive Effects
Recycled aggregates can have a rougher surface texture than natural aggregates, which can increase the bond strength between the aggregates and cement paste and improve the overall strength of the concrete.
The use of recycled aggregates can reduce the amount of cement needed in the mix, which can lead to a reduction in the water-cement ratio and an increase in the strength of the concrete.
Using recycled aggregates can also help to reduce the overall carbon footprint of the concrete, as it reduces the need for mining and transportation of natural aggregates.
Negative Effects
The quality of recycled aggregates can vary significantly, and aggregates containing contaminants or impurities can weaken the resulting concrete and reduce its strength.
Recycled aggregates are generally weaker than natural aggregates, and this can lower the overall strength of the concrete.
The presence of smaller particles in the recycled aggregates can lead to a higher water absorption rate, which can weaken the concrete over time.