Mix: The ratio of cement to sand and gravel, by volume or weight.
Mortar: A mixture of cementitious material and aggregate, used for bonding bricks and other masonry units together.
Mortar mix: A premixed, factory-produced mortar that requires only the addition of water.
Grout: A highly fluid form of mortar used to fill voids.
Overrun: The state of a project where you have more tasks or activity than can be completed with the available resources.
A project can be considered to be in overrun if the planned amount of work cannot be completed with the resources available. This is not necessarily a bad thing, it is often not possible to get a very accurate estimate of how much work will be required until some time into the project. If, at this point, additional resources are brought in, then there is no problem.
However, overrun is often used as an excuse for projects that have been inadequately planned and managed. The most effective way to avoid overrun is to ensure that the initial estimates are based on sound information and are realistic. Where possible it is useful to build in contingency allowances that can be used if the project goes over budget or takes longer than expected.
I have a special interest in the concept of overrun because I used to be an architect. The problem is that buildings are made of stuff: steel and concrete, glass and bricks, plywood and copper pipe. And this stuff has to be delivered to the site, where it has to be handled by people who don’t want to spend all day moving it around.
If you want to lay a thousand bricks tomorrow, you have to order them today. You can only lay so many bricks in a day—and you can’t lay any if they haven’t been delivered. So the more efficient you are at laying bricks, the more likely you are to run out of things to do while waiting for materials to arrive. The more efficiently your bricklayers work, the worse your overrun will be on any given day.
This is one reason big construction projects tend not to finish on time: the bigger they are, the more efficient each individual part is at using its resources. And yet in order for them all to finish on time, every part has to be inefficient enough as a whole that its resources are never idle. It’s like trying to run a marathon where everyone starts at different places and runs at different speeds, but still has to cross the finish line at exactly the
We’ve tested this mortar mix in our lab, and the only way to get it to work right is to use twice as much mortar per brick as we said originally.
Can you overrun the project schedule?
No, I don’t think so. We can overrun the budget, but the schedule is pretty tight. We’d have to slip some milestones by a month or so and that would disrupt other projects that depend on us.
What about if you paid overtime?
We could increase labor costs for those weeks but I’m not sure we could hire enough skilled people at short notice to do it all.
A mortar mix is a critical and vital component of any masonry construction. Its correct proportioning and preparation is essential to the success of the project.
The Portland Cement Association (PCA), with input from sand, masonry cement, and contractor representatives, developed this guide to assist designers in determining mixes that will provide the most effective mortars for a particular site or application. The guide also provides guidelines for establishing appropriate mix proportions for different types of mortars.
Mortar is a mixture of sand, water and cement. It’s used in masonry construction to hold bricks together and fill the spaces between them. It’s also used as a plastering material for finishing walls and ceilings.
Definition: The ratio of water, sand and cement in mortar depends on the type of bond to be provided. The major proportion is sand, which is about 70% to 80% of the total aggregate by volume. Cement is a binder and its proportion is about 10% to 12% by volume.
The additional water required over that absorbed by the aggregates represents the water used for hydration of the cement and shrinkage. This water is called free water. As per IS:1661-1965, free water should not exceed 60% by weight of hydrated cement or 32% by weight of dry cement.
The proportion of mortar depends on the size of brickwork and workability requirement. It may be 1:6 to 1:8 for thin joints (less than 10mm) and 1:4 for thick joints (20mm).
A mix of one part cement, three parts sand and three parts aggregate will produce a concrete mix of approximately 3000 psi. Mixing water with the cement, sand, and stone will form a paste that will bind the materials together until the mix hardens. The strength properties of the concrete are inversely proportional to the water/cement ratio. In other words, the more water you use to mix the concrete (very fluid) the weaker the concrete mix. The less water you use to mix the concrete (somewhat dry but workable) the stronger the concrete mix.
Aggregate is classified in two basic types, coarse and fine. Coarse aggregate is usually greater than 4.75 mm (retained on a No. 4 sieve), while fine aggregate is less than 4.75 mm (passing the No. 4 sieve). The compressive strength is measured by breaking cylindrical concrete specimens in a compression-testing machine. The compressive strength is calculated from the failure load divided by the cross-sectional area resisting the load and reported in units of pound-force per square inch (psi) in US Customary units or megapascals (MPa) in SI units.
The water–cement ratio is defined as the