FAQ

A 

Abram’s law – A law used to predict the compressive strength of cement and other similar materials. The law states that concrete strength is inversely related to the ratio of water to cement.   

Accelerator – A chemical added to a concrete mix to reduce the set time by increasing the rate of hydration. 

Admixture – A natural or manufactured additive in freshly mixed concrete that enhances specific properties like durability, workability, and strength. 

Aggregate – A mixture of sand or crushed stone as well as expanded materials or particles that enhance the structural performance of concrete and improve paste formation and flow.  

Apron – A slab of concrete that extends beyond the entrance of a building. 

B 

Bleed water/bleeding – The water that rises to the surface of freshly placed concrete.  

Blistering – The loss of adhesion with the underlying substrate.  

Bond – The adhesion or grip of a material to a surface. 

Bonding agent – A chemical agent that increases adherence to a given surface.  

Bond breaker – A material that keeps other materials from adhering to the concrete. 

Bull float – A tool used to smooth surfaces after pouring fresh concrete.  

C 

Calcium chloride – An accelerating admixture that increases the rate of hydration in cooler, damp conditions so as to decrease the curing time of concrete. 

Cast in place – To place and finish in its final setting. 

Cement – A component of concrete that hardens when mixed with water and sand and other fine aggregates. 

Cement hydration – This is the cement and water reaction that makes concrete and other cement-based materials harden. 

Concrete – A combination of water, chemical additives, aggregates, and cement.  

Consistency – The flow of freshly mixed concrete, measured as “slump.” 

Control/Contraction joint – A groove made in concrete to regulate its cracking location. 

Cubic yard – A measuring unit used to order, sell and measure the volume of a ready-mix concrete batch. 

Curing – Any action taken to maintain proper moisture and temperature conditions of freshly placed concrete after placement to ensure adequate hydration and proper hardening. 

Curing compound – A liquid that either forms a membrane or penetrates the concrete to delay the evaporation of water when applied to newly placed concrete.   

D 

Drying shrinkage – This is the decrease in the volume of concrete as it losses moisture.  

F 

Finish – The smoothing, leveling, compacting, and final treatment of newly placed concrete. 

Flexural strength – The ability of hardened concrete to resist bending failure. 

Float finish – Surface texture obtained by finishing with a bull or a hand float. 

Fly ash – A supplementary cementitious material byproduct of the combustion of ground or powdered coal. 

Finishing – The compacting, leveling, smoothing, etc. of recently placed or fresh concrete. 

G 

Gravel mix – A concrete mix containing either pea gravel or larger smooth gravel as the coarse aggregate.  

H 

Hydro blasting – The process of removing imperfections from concrete surfaces with a high-pressure water stream. 

K 

Kerf – A saw or router cut into a concrete surface. 

Kneeboards – Used by concrete finishers to kneel when hand floating or troweling concrete flatwork. 

M 

Membrane – A layer formed over a concrete surface that provides protection and enhances color such as acrylic, plastic, epoxy, or polyurethane. 

Mix design – Specific proportions of cement, aggregates, water, and admixtures to produce concrete for a specific kind of job. 

P 

Penetrating sealer – A sealer that penetrates the concrete surface to repel water.  

Permeability – This is the degree to which gas or liquid penetrates a coating or membrane. 

Plastic – The condition of freshly mixed concrete that indicates it’s ready to shape or cast. 

Portland cement – A hydraulic product that hardens upon interacting with water.  

R 

Raveling – This refers to dislodging aggregate at the edges of scored patterns or joints in concrete. 

Ready-mixed concrete – A batch of concrete mixed prior to its delivery for placement at a job site. 

S 

Sack – A 94-pound bag of Portland cement. 

Sack mix – This refers to the sacks of cement used in a cubic yard of concrete.  

Set – The condition reached by concrete when it attains full rigidity. 

Setting time – This is the measurement of the time it takes for concrete to harden. 

Slump – This is a measure of the consistency of freshly mixed concrete. 

Subgrade – The prepared and compacted soil made to support a structure or pavement system. 

V 

Volumetric mixer – A concrete mixer that measures and produces plastic ready mix by volume.  

W 

Water-to-cement ratio – The amount of water and cement used in a concrete mixture.  

Workability – The ease with which one can mix, place, and finish concrete and other cementitious materials.