Low-Cement Concrete (LCC) Mixtures for Bridge Decks and Rails

The University of Nebraska started a research project back in 2021 looking into Low-Cement Concrete Mixtures for Bridge Decks and Rails. Due to the current NDOT concrete mixture for bridge decks and rails (known as 47BD) requires at least seven sacks of cementitious materials (IP/IT) per cubic yard and a minimum compressive strength of 4000 psi. Based on the preliminary results from mixes prepared in the laboratory by the University, the Lower Cement Content (LCC) mixes show the following characteristics listed below. (1) Slightly lower workability (i.e. slump and flow) than 47BD, which requires higher dosage of superplasticizer. (2) Optimized 47BD-Cement Reduce 100lbs (O47BD-100) and O47BD-R150 have significantly longer set time (initial and final) compared to O47BD-R50 and 47BD. (3) LCC Mixes shows mechanical properties (Compressive Strength, Modulus of Elasticity and Flexure and bond strength) comparable to the 47BD control. (4) Durability properties (F/T, resistivity, and permeability) of LCC are comparable or even superior to those of 47BD. (5) Shrinkage Results LCC mixes shows less shrinkage than the 47BD control. The Materials and Research PCC Engineer is proposing to perform all the mixes listed in Table 2 from a ready mixed truck to confirm the mechanical and durability properties. As well as, introducing E5 Internal Cure and E5 Liquid Fly Ash for the of placement improving workability, longer window for finishing, minimal bleed rate, consistence air entrainment and enhancing cement/paste reduction.