Pouring concrete is a straightforward job. You dig, form the mix and pour.A wet ground is not the best base for newly poured concrete. You can do a few things to help the ground dry up just enough for you to pour your concrete.The Slump test is really a variant of the SLR and the Lasègue’s tests performed in the seated position and is a progressive series of maneuvers designed to place the sciatic nerve roots under increasing tension.The slump test is basically a measure of the consistency of fresh concrete or its workability.Once the concrete subsides the difference in height to the original height of the slump cone is measured as the slump.Shear slump indicates lack of cohesion in the concrete mix. Shear slump may occur in the case of a harsh mix.Workability is a property of raw or fresh concrete mixture. In simple words, workability means the ease of placement and workable concrete means the concrete which can be placed and can be compacted easily without any segregation.3000 PSI concrete is a standard multipurpose mixture for general use in construction. It is durable, has sufficient cement to provide good finishing characteristics, and can be placed fairly wet without sacrificing quality.The general size of the aggregate pieces used in concrete is between 0.75 and 1 inch. This is acceptable for a driveway; however, you may want to consider using smaller aggregate pieces to reduce the risk of potentially sharp stones popping out of the concrete over time.The lower the amount of water in a traditional concrete mix, the lower its slump. Low slump values in traditional mixes generally mean higher quality concrete. The additional ingredients in modern concrete mixes make it impossible to determine concrete quality from slump, however.
The common way to slow the hardening of concrete is to employ an admixture termed a retarder.Retarders are primarily intended to counteract the harmful results of heat on the concrete mix; they lower the water/cement ratio only as a side effect. Just remember, don’t use retarders in cold weather.Pouring Concrete vs Pouring Rain.If the rain occurs when the concrete is fresh (about 2-4 hours after mixing), the surface should be protected from the rain. If the finishing process was recently completed, rainwater may not cause damage as long as it is not worked into the surface and the slab is left untouched.The slump test is a means of assessing the consistency of fresh concrete. It is used, indirectly, as a means of checking that the correct amount of water has been added to the mix. The test is carried out in accordance with BS EN 12350-2, Testing fresh concrete.When measuring the workability and consistency of a batch of concrete, a concrete slump test must be performed for each batch of fresh concrete.The cone is filled with concrete, and then removed. The shape of the concrete after the cone removal is then assessed to determine the workability.There are three types of slump that may occur in a slumps test, namely, true slump, shear slump and collapse slump. True slump refers to general drop of the concrete mass evenly all around without disintegration. Shear slump indicates that the concrete lacks cohesion.
In making concrete strong, these ingredients should usually be mixed in a ratio of 1:2:3:0.5 to achieve maximum strength. That is 1 part cement, 2 parts sand, 3 parts gravel, and 0.5 part water.Concrete hardens as a result of a chemical reaction, called hydration, between cement and water, not because it dries.Concrete continues to gain strength after pouring for as long as it retains moisture, but the longer it moist-cures, the slower the rate of strength gain.Concrete finishers here tell me that a slab poured outside on a hot day won’t cure properly unless it’s kept wet.It simply makes the concrete set more slowly, which would actually make curing more critical. For concrete to reach its full strength, it needs water to hydrate the cement.Water can be bailed or pumped out, and the soil at the base of the hole can be compacted. The concrete you pour into the hole will displace the water, this is called wet-placing concrete. Big Foot form tubes can also be installed to keep the water out of your concrete pour.Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Gravel is especially important in clay soil because it doesn’t drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains.