Looking For Cement, Aggregates Or Building Sand? Take A look At this Page Where You Will Find 25kg Bags & Bulk Bags For Those Bigger Jobs. What Is Cement? Cement Is A Fine, Soft Powder Used As A Binder Because It Hardens After Contact With Water. It Is Made From A Combination Of Limestone And Clay That's Charred And Then Ground Up. What Is Aggregate? Aggregate Is A Combination Of Gravel & Sand Which Forms A Rough, Coarse Aggregate Used In An Extensive Range Of Construction Applications. Commonly Used In Heavy-Duty Work And For Practical Uses Such As Making Concrete. What Is Sand? Sand Forms When Rocks Break Down From Weathering And Eroding Over Thousands And Even Millions Of Years, We Now Use This As A Source Of Building Supplies All Over The World.