Two Rates

Then, for this—there should be two tie columns in the middle of a 500-mm wall. At this point, you need to pay attention to the key points. Also remember that the daily masonry height must not exceed 1.5 m; construction can resume on the second day. As we discussed earlier, when a certain method is adopted, structural columns must be added; if the wall exceeds 5 m in length or 20 times its thickness, tie columns must be added in the middle. At the same time, if the wall height exceeds 4 m, horizontal tie beams must be reinforced. In this way, for a very large and tall wall, its stability will naturally improve. Exams often focus on this diagram. There are also material requirements, which we have already covered: concrete blocks; third, different types of aerated blocks must not be mixed, and blocks of different strengths must not be mixed either. Pay a little attention to that. For sintered bricks, every 100,000 bricks or 10,000 bricks are treated as one inspection batch; generally, we use 150,000 bricks. For hollow bricks, every 100,000 bricks or 10,000 bricks are one batch, and concrete must be at least C20, because they are prone to dampness along the holes. Likewise, let us look at an example. This is an error-correction question. Look: the infill wall masonry used single-row-hole lightweight aggregate concrete small blocks and special small-block mortar—there was no problem with that. During inspection, it was found that the small-block products began to be watered after reaching 21 days. The 21 days are wrong; what we need is 28 days. Watering, correct? That is correct, because these are lightweight aggregate concrete small blocks; watering begins after the surface water has evaporated. Construction must not be carried out on rainy days—two errors. Continuing on: