Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

Abstract

Type of Report and Period Covered14. Sponsoring Agency Code 15. Supplementary Notes 16. Abstract: This Phase II investigation into the durability of new concrete incorporating recycled concrete aggregates (RCA) focused on several goals: 1) Provide corroboration of results obtained in Phase I for a multi-laboratory study related to assessing alkali-silica reactivity (ASR) of RCA in accelerated laboratory tests; 2) Investigate the efficacy of mitigation methods to control ASR in concrete containing potentially reactive RCA; 3) Establish long-term data through placement of concrete blocks containing RCA in an outdoor exposure site in Laramie, WY; and 4) Survey state DOTs and other transportation agencies about their perceptions and usage of RCA ASR in concrete within their agency and how that may be improved through the use of a database tracking tool. From Phase II the following main conclusions were drawn: 1) The coefficient of variation limits in ASTM C 1260-07 do not apply to concrete mortar bars incorporating RCA. It is recommended that further testing, using different RCA and more laboratories (at least six), should be completed before a new standard for RCA and/or incorporation of RCA into the current ASTM C 1260 test may be allowed. 2) Generally, as the replacement level of RCA was reduced, the amount of SCM needed to control deleterious ASR also decreased for the RCA sources investigated in this study. 3) Ternary blends containing metakaolin resulted in the most significant decrease in expansions compared to the mixtures with no SCMs.The results of the transportation agency survey showed the following: 1) A vast majority of agencies believed that sustainability was important to their agency and that it was addressed in a clear and meaningful way. 2) A majority, 54%, of agencies believed they had specific guidance for the use of RCA in new concrete; however, only 15% believed that there was strong information from the federal level about the use of RCA in new construction. 3) Of all respondents, 77% indicated their agency was concerned about alkali-silica reaction in concrete in general for their agency. 4) The biggest barriers to using RCA were noted as concerns about quality, a lack of standards and specifications, and unclear guidance on the testing of RCA. 5) The biggest concerns specific to a source of RCA when considering it for use in new construction were increased shrinkage concerns, ASR and residual chlorides. 6) The most sought-after information about a potential RCA source when considering it for use were the existing condition of the RCA when it was taken out of service, the reason it was taken out of service, whether repairs were performed to the structural element taken out of service, and the age of the RCA. 17.

Fostering a circular economy and carbon sequestration for construction materials workshop report:

“…As depicted in Figure 2, C&D debris comprises a variety of materials, with concrete accounting for the largest portion at nearly 68 %. In the U.S., concrete debris is used as recycled concrete aggregate (RCA) in pavement subbase (i.e., road-base), non-structural backfill, or disposed of in landfills [12,13,14]. According to U.S. EPA data, in 2018, over 300 million tons of concrete C&D debris was utilized in some form, while 71 million tons was discarded in U.S. landfills [12].…”

مقایسه ی عملکرد الیاف پلیمری ماکرو و الیاف فولادی به لحاظ کنترل ترک خوردگی ناشی از جمع شدگی خشک شدن بتن

“…V}=tR; s=Hv= =@ Q}O=kt u}= Ow@ xOWv XNWt u=oOvvmO}rwD \UwD |WWm Ctw=kt "OW u}}aD [21] ASTM1557 OQ=Ov=DU= j@] h=}r= xD}U}DUq= pwOt u}}aD "xO=iDU= OQwt h=}r= Q} w=YD "1 pmW "OvQDO}OH |Oqwi h=}r= w wQm}t |Qt}rB h=}r= =@ xU}=kt QO wQm=t |Qt}rB h=}r= OQ=Ov=DU= C=t= Rr= j@] w CU= QDt|r}t 60 =D 30 , =OwOL h=}r= u}= pw] "CU= QDt|r}t 0 3 R= QDW}@ wQm=t h=}r= pO=at Q]k [14] ASTM C1116 xJv; R= QDq=@ Q}O=kt QO = Q h=}r= u}= R= xO=iDU= wQm=t |Qt}rB h=}r= QDnQR@ O=a@= u}= |wQ xOW s=Hv= C=k}kLD "OR=U|t umtt CU= pwtat wQm}t h=}r= |= Q@ xOw@ OwOLt , =D@Uv |oOW`tH R= |W=v |oOQwNlQD pQDvm ^=Lr x@ h=}r= `wv |Qt}rB h=}r= ?U=vt OQmrta |aOt h=}r= u}= |xOvvmO}rwD |=yCmQW "CU= xU}=kt QO h=}r= u}= OQmrta xm xO=O u=Wv C=k}kLD |NQ@ =t= 'OvDUy wQm=t Qo}O G}=Dv u}vJty [15] "CU= QDh}a[ 'hQYt Q@=Q@ Q=Okt QO '|Oqwi h=}r= =@ p@=k Cw=iD OYQO 0 25 OwOL u}}=B hQYt Q}O=kt QO xm OyO|t u=Wv =y|UQQ@ |oOQwNlQD u=tR uDN=Ov= Q}N -=D x@ QO |Qt}rB h=}r= w |Oqwi h=}r= u}@ |yHwD OQmrta Qou=}@ hQYt |q=@ Q}O=kt QO h=}r= u}= OQmrta |xU}=kt &OQ=Ov OwHw x@ OwOLt xm R}v u= Q=mty w x}iUw} Q}N= j}kLD [10] "CU= |Oqwi h=}r= QDy@ OQmrta sOa R= |m =L xOw@ wQm=t |Qt}rB h=}r= R= xO=iDU= OYQO 0 2 |xv}W}@ R= |W=v lQD `wkw u=tR uDN=Ov= j} waD x@ QO xO=iDU= sm Q}O=kt QO h=}r= u}= OQmrta XwYNQO [17] u= Q=mty wYin |=y|UQQ@ [16] "CU= xOw@ |oOW`tH |Ov@`tH uOW lWN R= |W=v |oOQwNlQD pQDvm ^=Lrx@ 'R}v hrDNt h=}r= Q@ h=}r= QF= OQwt QO xOW s=Hv= |=y|UQQ@ Qo}O "CU= xO=Ov x=Q= |YNWt XwYN u}= QO |UwULt Q}F -=D h=}r= Qw[L xm OyO|t u=Wv [18] O= R; |wQ [23] u= Q}= 3206 OQ=Ov=DU= j@] xOW xDN=U |=y\wrNt |Q=Wi Ctw=kt |r} RQ@ V}=tR; "OW u}}aD RwQ 28 uU QO QDt|Dv=U 10 O=a@= x@ |@amt |=yxvwtR; ASTM C496 OQ=Ov=DU= j@] hrDNt |=y\wrNt |WWm Ctw=kt u}}aD |= Q@ "OW s=Hv= QDt|Dv=U 10 20 |}xv=wDU= |=yxvwtR; |wQ [24] O= R; |oOW`tH "2"4"2…”

“…x@ |QwWvt |=yxvwtv |wQ [25] ASTM C157 OQ=Ov=DU= j@] O= R; |oOW`tH COt x@ ?w]Qt |Qw;pta R= TB "OW s=Hv= QDt|r}t 75 75 275 O=a@= QO w xOW |Q=Oxov OYQO 50 5 |@Uv C@ w]Q =@ |]}Lt QO =yxvwtv 'RwQ Ciy 0 002 CkO x@ QwD= QBt=m x=oDUO =@ =yu; O= R; |oOW`tH u= R}t hrDNt |=yu=tR "3 pmW OW |Q}oxR=Ov= QDt|r}t "wQm=t |Qt}rB h=}r= xD}U}DUq= pwOt u}}aD V}=tR; "2 pmW xar=]t OQwt |=y\wrNt "3"2 h=}r= hrDNt |=yOYQO w xOw@ u=Um} =y\wrNt |t=tD |= Q@ x}=B \qDN= KQ] ? ; C@Uv w ?amt QDt Q@ sQowr}m 400 u=t}U Q=Okt "OW xi=[= x}=B \wrNt x@ =y\wrNt |xty |= Q@ \UwDt AtqU= "CU= xOW xDiQo Q_v QO 0 46 u=t}U x@ QO QDt|Dv=U 9 =D 5 [22] u= Q}= 3519 OQ=Ov=DU= "OwW|t xDiQo Q_v QO |oOQwNlQD p}Uv=DB R= |Q=}at u=wva x@ w Q=yJ x@ lQD `wkw Xr=N u=tR T=U= Q@ = Q |vD@ |=y\wrNt ASTM C1581 =@ w \UwDt =D sm p}Uv=DB =@ 'O=}R =D \UwDt p}Uv=DB =@ 'O=}R p}Uv=DB =@ xOQ |oOQwNlQD u=tR =@ |=y\wrNt "Ovm|t |Ov@s}UkD |oOQwNlQD sm p}Uv=DB Xr=N u=tR [26] 'Ov=xOQm xO=iDU= O}kt |oOW`tH ASTM C1581 OQ=Ov=DU= j@] O}kt |xkrL |oOW`tH V}=tR; 'xOW u} wOD hrDNt |=y\wrNt OQmrta |@=} RQ= |=v@t Q[=L j}kLD QO V}=tR; u}= [19] "CU= C=aq]= w wU l} R= QwWm QO V}=tR; u}= |@Uv uOw@ O}OH x@ xHwD =@ "CiQo Q= '?r=k w xkrL O=a@= x@ xHwD =@ "OwQ|t Q=m x@ QDt|r}t 405 |rN=O Q]k =@ lR=v |Q}o?r=k R= TB "OwW|t pY=L QDt|r}t 40 =@ Q@=Q@ |vD@ |xkrL Ct=N[ C@ w]Q GwQN R= =D OW xO}WwB uwr}=v =@ =yu; |}q=@ K]U |wQ xrY=iq@ '=yxvwtR; uOQwN lQD w uOW lWN `wQW u}@ u=tR COt =@ CU= Q@=Q@ (t cr ) lQD '|Oqwi h=}r= hQYt Q=Okt V}=Ri= =@ OwQ|t Q=_Dv= 'uD@ =@ xU}=kt QO Oqwi |q=@ h=}r= hqNQ@ hQYt OYQO 1 QO wQm=t |Qt}rB h=}r= "O@=} Ow@y@ |WWm Ctw=kt Q=}U@ |v=UWm pwOt x@ xHwD =@ "CU= xOW |WWm Ctw=kt Vy=m Ea=@ |Oqwi Q}O=kt QO h=}r= u}= VNB QO |Q=wWO R}v w uD@ =@ xU}=kt QO |Qt}rB h=}r= QDsm |m}v=mt X=wN Q@ h=}r= Q}F -=D =@ x]@=Q QO "CU= Q=_Dv= p@=k xOW xOy=Wt OvwQ 'q=@ Q}F -=D xm CU= u; Qov=Wv |twta |Ov@`tH "CU= xOW s=Hv= |O=}R C=ar=]t uD@ |wQ OYQO w [18] |Qt}rB h=}r= QF= XwYNQO xOW s=Hv= |UQQ@ R= pY=L G}=Dv x@=Wt 'Q[=L 7 pmW QO 'xrY=L G}=Dv R= |}xvwtv u=wva x@ "CU= xOw@ [12] |Oqwi h=}r= QF= R}v "O= R; |oOW`tH Q@ xO=iDU= |tHL 1 QO h=}r= QF= "7 pmW wO |= Q@ VvQm MQv QwDm=i u}ov=}t uDiQo =@ ( avg ) VvQm QwDm=i \UwDt MQv MQv x@U=Lt |= Q@ xt=O= QO "O};|t CUO x@ xkrL Qy |wQ xOW ?Yv GvUVvQm "OwW|t xO=iDU= 2 |x]@= Q R= |vD@ xkrL QO |WWm VvD |xaUwD q = Gj avg j…”