The setting process of cement is irreversible up to a point and is dependent on weather conditions plus water content of the finished mix. In hot summer weather we would reconstitute (or knock-up as we called it) mortar when it was setting too quickly,but only up to a point because it interferes with that setting process.There's comes a time when you have to chuck it and mix a new batch.
Conversely,in winter the setting process is generally slower and quantity of water should be regulated accordingly. More specific to slab laying,generally speaking the larger the slab the drier (or stiffer) the mix can be,as too wet a mix can result in the weight of the slab simply displacing the mix. So generally - larger slab,drier mix - smaller slab,wetter mix
It helps to wet the bottom of the slabs as you lay them so they don't pull all the moisture out of the cement. Also the sharp sand allows water to drain through building sand holds onto the water.
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The setting process of cement is irreversible up to a point and is dependent on weather conditions plus water content of the finished mix. In hot summer weather we would reconstitute (or knock-up as we called it) mortar when it was setting too quickly,but only up to a point because it interferes with that setting process.There's comes a time when you have to chuck it and mix a new batch.
Conversely,in winter the setting process is generally slower and quantity of water should be regulated accordingly. More specific to slab laying,generally speaking the larger the slab the drier (or stiffer) the mix can be,as too wet a mix can result in the weight of the slab simply displacing the mix. So generally - larger slab,drier mix - smaller slab,wetter mix
It helps to wet the bottom of the slabs as you lay them so they don't pull all the moisture out of the cement. Also the sharp sand allows water to drain through building sand holds onto the water.