Super-accurate aircrete blocks cut brickie build time
Rob Peters rates the latest aircrete blocks from H+H Celcon for the most compelling of reasons. He reckons Plus and Jumbo Plus – the two new behemoths on the block – take as much as a third off the build time of his projects and make aircrete as fast as timber-frame construction.

A contracts manager with Steve Murphy Brickwork, Peters says the perfect shape of the blocks (see 'What A Drag') means the bricklayer doesn't have to spend as much time checking and levelling each course of blocks. Laying Plus and Jumbo Plus blocks still needs skill but it doesn't demand years of expertise.

Building with them is almost laughably easy. "It's very similar to Lego," says Peters, although he warns that getting the foundation course of blocks right is the key to it all working so easily.

But dimensional accuracy isn't the only reason why Plus and Jumbo Plus help builders pick up the pace. While bricklayers can also use Plus blocks with conventional mortar, Jumbo Plus is specifically designed for thin-joint mortaring.

Applying a 3mm layer of thin-joint glue, rather than the conventional 10mm of mortar, speeds up block laying twofold. First, it sets far faster than the 24-hour cure time required by ordinary mortar. "You get a good grab in 10 minutes," says Ian Exall, marketing director of Celcon. "It's set in an hour, and after that you'd need a sledgehammer to knock them down."

So instead of getting a block wall up to waist height and then having to get on with something else until the next day, bricklayers can continue laying blocks with thin-joint, taking them straight up to the roof without the bond swimming. And that allows follow-on trades to get started faster.

Thin-joint is also quicker to apply: a scoop with serrations dispenses the right amount and thickness. So there is no need to constantly measure courses and correct accordingly for too much or too little mortar.

Plus and Jumbo Plus are much larger than anything else Celcon produces. At 610mm, they are longer than the standard 440mm, while the 270mm-high Jumbo Plus dwarves the 215mm height of the rest. But neither block breaks the 20kg limit on manual handling.

According to Peters, around 30% of his company's jobs involve thin-joint and aircrete construction. "The old blocks made it easy," he says. "The new ones make it easier still."

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What a drag

Most aircrete factories were built a decade ago when there was less demand for dimensional accuracy. But a new plant allows Celcon to make Plus and Jumbo Plus to consistently accurate dimensions. Manufacturers typically use oscillating wire cutters to divide up the huge cakes of cellular concrete they make into the aircrete blocks they sell. By dispensing with the oscillations, Celcon’s new production process reduces the length of wire that goes through the aircrete and, with it, the amount of drag that compromises the accuracy of the cut. And whereas oscillating cutters leave scratches on the faces of blocks, construction teams can use thin-coat spray-on plaster with smooth-faced Plus and Jumbo Plus, further speeding up construction work.

Source

Construction Manager