Compressive Strengths of Various Mortar Mixes Containing Synthetic Lightweight Aggregate.pdf

Chris Swan, Tufts University

Description

Compressive Behavior of Various Mortar Mixes Containing Synthetic Lightweight Aggregate Authors Prof. Chris Swan - United States - Tufts University Abstract This paper presents strength and small strain results of mortar concrete mixes, some of which contained synthetic lightweight aggregates (SLAs) – a construction material created from waste plastic and coal fly ash. Twelve mortar mixes were created using a sand-size aggregate that satisfied ASTM’s standard C33 gradation for fine aggregate; i.e., aggregate particles ≤ 4.75mm in size. A 3-by-4 matrix for mix designs was developed; i.e., three different water-to-cement (w/c) ratios of 0.45, 0.55, and 0.65 were used to create concretes with four different SLA contents; 0, 6.67%, 15.6%, and 31.1%. Uniaxial compression tests, outfitted with an on-specimen device to capture small strain measurements, were performed on two to three specimens of each mixture. Testing was performed after 28-day curing. In summary, the peak strength (f’c) of the 0%-SLA-content concretes decreased as the w/c ratio increased; from a peak of 47.4 MPa for a w/c=0.45 to 31.7 MPa for w/c=0.65. At each w/c ratio, as the SLA content of the concrete increased, the peak strength also decreased. Both of these behaviors/trends were as expected, having been found in previous research. The measured Young’s moduli of the concretes showed a tendency to decrease as the strength decreased with w/c ratio and/or SLA content, but the rate of moduli decrease was greatly reduced as SLA contents increased, with the rate becoming near zero at SLA contents of 31.1%. Additionally, the results indicated at lower w/c ratios, the moduli could increase for small SLA contents (≤ 6.67%), though the f’c would decrease for such concretes. It is apparent that the presence of SLA does have an impact on the small strain behavior of concretes, at times counter to that of a change in w/c ratio. Future studies will further examine these moduli phenomena.

 
May 16th, 8:00 AM May 16th, 8:30 AM

Compressive Strengths of Various Mortar Mixes Containing Synthetic Lightweight Aggregate.pdf

Grand Rapids, Michigan

Compressive Behavior of Various Mortar Mixes Containing Synthetic Lightweight Aggregate Authors Prof. Chris Swan - United States - Tufts University Abstract This paper presents strength and small strain results of mortar concrete mixes, some of which contained synthetic lightweight aggregates (SLAs) – a construction material created from waste plastic and coal fly ash. Twelve mortar mixes were created using a sand-size aggregate that satisfied ASTM’s standard C33 gradation for fine aggregate; i.e., aggregate particles ≤ 4.75mm in size. A 3-by-4 matrix for mix designs was developed; i.e., three different water-to-cement (w/c) ratios of 0.45, 0.55, and 0.65 were used to create concretes with four different SLA contents; 0, 6.67%, 15.6%, and 31.1%. Uniaxial compression tests, outfitted with an on-specimen device to capture small strain measurements, were performed on two to three specimens of each mixture. Testing was performed after 28-day curing. In summary, the peak strength (f’c) of the 0%-SLA-content concretes decreased as the w/c ratio increased; from a peak of 47.4 MPa for a w/c=0.45 to 31.7 MPa for w/c=0.65. At each w/c ratio, as the SLA content of the concrete increased, the peak strength also decreased. Both of these behaviors/trends were as expected, having been found in previous research. The measured Young’s moduli of the concretes showed a tendency to decrease as the strength decreased with w/c ratio and/or SLA content, but the rate of moduli decrease was greatly reduced as SLA contents increased, with the rate becoming near zero at SLA contents of 31.1%. Additionally, the results indicated at lower w/c ratios, the moduli could increase for small SLA contents (≤ 6.67%), though the f’c would decrease for such concretes. It is apparent that the presence of SLA does have an impact on the small strain behavior of concretes, at times counter to that of a change in w/c ratio. Future studies will further examine these moduli phenomena.