As you say Bonding Coat is harder for a novice to flatten but can be easier to build up this thickness due to the set helping you out. However there is no reason why Sand & cement cannot be used - just apply diluted PVA (water, pva and a handful of sand mixed in to give an extra key) to the existing plaster.
Browning plaster is similar to bonding plaster in that it can be used as a base undercoat or backing coat. Ideal for use on absorbent surfaces, such as common bricks.
Cement plaster is made by mixing cement, sand, and water, usually, the ratio of cement and sand is 1:4. The thickness of plaster depends on the surface to be plastered and could be around 12 to 20 milliliters. Sometimes, plasticizers are also mixed in the plaster to protect walls from parasites.
If you are using a pointing mix, then you should have a ratio of 1:4 or 1:5 mortar to sand. As for concrete, it depends on the strength you need it to be at. Usually, it is good practice to mix concrete at 1:2 mix to materials.
Why Won't My Mortar Stick? Most of the time this is a result of an incorrect ratio between cement and sand – if you have too much of the latter and not enough of the former, the adhesive effectiveness will be greatly reduced.
Cement is a complex chemical glue. When mixed with water, and any other inert durable material such as: sand & stone, it will set as hard as rock and remain extremely durable to impact, heat, abrasion and weathering. Another interesting characteristic of cement, is that it does not require air to set hard.
A chemical reaction takes place which causes the Cement to crystalize. And as it does so the Water component of the mixture becomes a part of the overall structure, and helps bind the Sand and the Stones together. This ultimately results in a solid mass which we call Concrete.
Although you can use cement for pointing older buildings, you shouldn't. Some of the common issues we see almost daily are linked to the use of cement mortar to repoint the brick or stone walls of traditional buildings.
The wrong type of repointing will also have serious consequences, causing further damage to stone and brickwork, trapping excess moisture and increasing the rate of decay. Cement based mortar should never be used to repoint historic walls, it is too strong, inflexible and impermeable.
Cement mix and mortar mix are ideal for a large selection of tasks including pointing brickwork and stone, repairing concrete and render and filling holes or setting posts. Ready mixed cement and quick-drying cement are perfect for multiple commercial, industrial, agricultural or smaller domestic projects.
I have often had the question asked if you can make concrete with just sand and cement, so can you? You cannot make concrete with only sand and cement because it requires a coarse aggregate like gravel. The stone component is the most critical, as that is what gives it its durability and strength.
It's important to realise that you cannot use cement alone and it will need to be mixed with other materials to make a concrete or mortar mix.
Generally, the thickness of a cement render should be between 6 and 25mm. However, a thicker render can be used for heavier-duty applications such as external walls.
If your referring to "bonding" as in a bonding coat of plaster then your answer is no. The wall will need a coat of Pva to reduce suction from the surface in preparation for skimming.
Plaster Bonder is a vinyl acetate homopolymer emulsion used to bond new plaster to any structurally sound interior surface. The bonder is required for applications of plaster over Durock® Brand Cement Board, Fiberock® Abuse-Resistant Gypsum Fiber Panels, and monolithic concrete.
Bonding plaster is intended as an undercoat, offering a great level of adhesion. It can be used over a variety of building materials, bonding well to almost every surface. As it is an undercoat, a top coat of plaster will be needed over it.
Mortar is a mixture of sand and cements that is most often used to build brick or block walls. While that may sound like the same recipe used to make concrete, there are some intentional differences between the formulations for mortar and cement, which is why the materials should not be used interchangeably.
Concrete will stick to some plastics, wood, metal, vinyl, cloth and other porous surfaces. But that's about it. Concrete won't stick to molds, smooth metal, glue, paint, oil, mortar, other concrete or most masonry products.
Add just enough water to achieve the right consistency, starting with about — gallons for a cubic foot of mix. Mortar that is too wet will run out between the joints. If it is too dry, the bond will be weak. Mound the mix and form a depression in the center.
The cement within a concrete mix doesn't contain any natural bonding agents – so when fresh concrete is added on top of an existing layer of concrete, the two won't join together. Once cured, the new concrete will simply sit on top as a separate layer. This will not produce a strong, serviceable floor.
Using Lime Mortar for Pointing or Repointing
Using lime mortar instead of cement for pointing stone masonry or brickwork is a wise choice. Lime is a softer material which allows moisture to move through the joints.
If pointing dries before sufficient carbonation has taken place then cracking can occur. Therefore regular misting with water and protection from the wind and the sun are crucial in tempering this process. mortar too wet – Pre-mixed fat lime mortars will rarely require the addition of any extra water.
It's worth noting that you can't use cement alone. You will need to mix the other materials with the cement (in the right ratio) to make your concrete or mortar mix. Knowing which material will be best for your project, at the correct ratio, is crucial to making your project a success.
Ready-made concrete bags are useful for much smaller projects – all you need to do is add water. Mortar is made of cement and sand – it's not as strong as concrete, but is usually used as a glue-type material – sticking down paving flags for patios, for example.
Sand and cement render is made by mixing 4 parts sand with 1 part cement and is applied to the substrate at a depth of about 10mm – 15mm.