Developing Sustainable High Strength Concrete Mixtures Using Local Materials and Recycled Concrete

Abstract

This study presents the development of high strength concrete (HSC) that has been made more sustainable by using both local materials from central Texas and recycled concrete aggregate (RCA), which has also been obtained locally. The developed mixtures were proportioned with local constituents to increase the sustainable impact of the material by reducing emissions due to shipping as well as to make HSC more affordable to a wider variety of applications. The specific constituents were: limestone, dolomite, manufactured sand (limestone), locally available Type I/II cement, silica fume, and recycled concrete aggregate, which was obtained from a local recycler which obtains their product from local demolition. Multiple variables were investigated, such as the aggregate type and size, concrete age (7, 14, and 28-days), the curing regimen, and the waterto-cement ratio (w/c) to optimize a HSC mixture that used local materials. This systematic development revealed that heat curing the specimens in a water bath at 50˚C (122˚F) after demolding and then dry curing at 200˚C (392˚F) two days before testing with a w/c of 0.28 at 28-days produced the highest compressive strengths. Once an optimum HSC mixture was identified a partial replacement of the coarse aggregate with RCA was completed at 10%, 20%, and 30%. The results showed a loss in compressive strength with an increase in RCA replacement percentages, with the highest strength being approximately 93.0 MPa (13,484 psi) at 28-days for the 10% RCA replacement. The lowest strength obtained from an RCA-HSC mixture was approximately 72.9 (MPa) (10,576 psi) at 7-days. The compressive strengths obtained from the HSC mixtures containing RCA developed in this study are comparable to HSC strengths presented in the literature. Developing this innovative material with local materials and RCA ultimately produces a novel sustainable construction material, reduces the costs, and produces mechanical performance similar to prepackaged, commercially, available construction building materials.

Mechanical Properties of Ultra High Performance Fiber Reinforced Concrete Made with Foundry Sand

“…However, there was no statistical significance between 0 -FS and 20 -FS, which is a favorable result as it shows that FS has no impact at a 20% replacement level, which can increase the sustainability of the material without sacrificing splitting tensile strength. As with the compressive strength results the effect of the FS reducing density and workability, along with the literature [29] demonstrating a reduction of SCM ability from the FS, had the same effect on the splitting-tensile strength, which is expected based on the literature [1][2][3][4][5][20][21][22][23][24][25][26][27][28][29].…”

“…200 sieve to remove any fine dust and particles. This helped to ensure there was no water lost due to fine dust River Sand Foundry Sand particles as recommended by the literature [5,7,[19][20][21][22]. After washing, the aggregates were oven dried at 110º C (230º F) for a minimum of 24 hours to achieve a 0% moisture content.…”

“…After thorough mixing, the HRWRA was added with the remaining 25% of the water. This mixing sequence was used based on of the literature and experience [20][21][22][23][24][25].…”

Study of the Technical Feasibility of Increasing the Amount of Recycled Concrete Waste Used in Ready-Mix Concrete Production

“…This issue is more pronounced in the case of fine recycled aggregates, as opposed to coarse recycled aggregates [ 40 ]. Incorporating fine recycled aggregates in high-strength concrete requires additional reinforcement [ 43 , 44 , 45 ]. Furthermore, since recycled concrete aggregate is always collected from different sources or types of concrete, the basic engineering properties, such as shape and texture, specific gravity, absorption, moisture content, permeability, strength characteristics, deleterious substances, resistance to freeze–thaw, etc., vary considerably.…”

“…Furthermore, since recycled concrete aggregate is always collected from different sources or types of concrete, the basic engineering properties, such as shape and texture, specific gravity, absorption, moisture content, permeability, strength characteristics, deleterious substances, resistance to freeze–thaw, etc., vary considerably. As a result, significant variations in the engineering properties of concrete made with recycled concrete aggregate have been reported [ 45 , 46 , 47 ]. In Japan, JIS has drafted a technical report, TRA 0006 “Recycled Concrete Using Recycled Aggregate” to promote the use of concrete made with recycled aggregate.…”