Search

Reconfiguring practices within the construction industry through the utilization of diverse industrial byproducts is a crucial endeavor. This study was devoted to promoting sustainable construction methodologies while mitigating environmental implications. The focus of the research was the incorporation of reclaimed asphalt pavement (RAP) aggregates into GPC for application as pavement quality concrete (PQC). Leveraging fly ash (FA) and ground granulated blast furnace slag (GGBS) as viable aluminosilicate sources emerged as a judicious strategy for formulating blends that exhibit exceptional attributes at ambient temperatures, thereby circumventing the challenges posed by impractical on-site oven curing. Natural coarse aggregates were replaced with RAP at varying percentages ranging over 25% to 100% and the performance of the binders was assessed across a range of NaOH molarities (10M to 16M). The 14-M, 50% RAP mix exhibited superior strength and durability, achieving permissible compressive and flexural strength after just 7 days of ambient curing (41.80 and 4.72 MPa, respectively), in contrast to the 28 day of curing required for conventional cement concrete. This designed mix also showcased significant resistance to surface abrasion and carbonation, along with exemplary thermal stability as determined by thermogravimetric analysis (TGA). Upon exposure to a 2% H2SO4 concentration (to gauge performance in aggressive environments), higher RAP replacement levels revealed to influence mass and strength loss, but the effect of molarity remained quite moderate. Furthermore, toxicity characteristic leaching potential (TCLP) tests confirmed the immobilization of heavy metals in GPC blends with integrated RAP, thereby endorsing their environmental suitability for the construction of rigid pavements. [ABSTRACT FROM AUTHOR]

The present study investigated the performance characteristics of concrete paver block (CPB) mixes with incorporated reclaimed asphalt pavement (RAP) aggregates under different curing regimes, namely, continuous water curing (WC), air curing (AC1 and AC2), intermittent water and air curing (WAC), water spray curing (WSC) and heat curing (HC). Seven CPB mixes were formulated by volumetrically replacing virgin coarse and fine aggregates partially and in combination with coarse RAP, fine RAP, and combined RAP fractions. For better refinement of agglomerated particles present in the RAP and to achieve a dense microstructure, the block specimens were fabricated using a design methodology that included a staged mixing approach and time-controlled compaction simultaneously with a vibratory hammer and table vibrator. Hardened CPB specimens were tested to assess mechanical (compressive, flexural, and tensile splitting strength) and durability (water absorption, porosity, and carbonation) properties of the concrete. CPBs fabricated from the considered RAP-inclusive concrete mixes manifested great potential to be used for pavement applications having medium to very heavy traffic when cured with the WC, WAC, WSC, and AC2 curing regimes. Curing regimes WAC and WSC, which involved a combination of water and air curing, were found to be the most effective for the RAP CPB mixes, resulting in superior strength properties. The presence of carbonation was detected in all the RAP CPB mixes when exposed to air curing (AC2) for a prolonged period of time. [ABSTRACT FROM AUTHOR]

This study discusses the effect of utilizing coarse reclaimed asphalt pavement (RAP) aggregates as a replacement to natural coarse aggregates (NCAs) for the production of pervious concrete pavement (PCP) mixes. Coarse RAP (RC) aggregates were utilized in proportions of 0%, 25%, 50%, 75%, and 100%, respectively. It was observed that the porosity and permeability coefficient of the PCP mixes increases considerably as the RAP replacement level increases. Meanwhile, the incorporation of RC was also found to negatively affect the mechanical properties of the PCP mixes. However, the compressive and flexural strength values were noted to be well within the prescribed limits (5–25 MPa and 1–3.2 MPa) required for a PCP mixture. On the other hand, the incorporation of RC was observed to reduce the hardened density, resistance to abrasion, and resistance against aggressive environment of chlorides and sulfates. Therefore, in order to prepare a PCP mixture such that there exists a fine balance in various properties, it is recommended that RC up to 50% may be utilized as a replacement to NCA. In view of achieving maximum sustainability, RC up to 100% may be completely utilized for the production of PCP mixes provided a binary gradation is adopted. Utilization of RAP in preparation of pervious concrete pavement mix will not only resolve the issues related to clearance of an enormous amount of RAP dumps, but would go a long way in dealing with various other environmental and ecological impacts. [ABSTRACT FROM AUTHOR]