Aes­thet­i­cal In­te­gra­tion in High Per­for­mance Con­crete for In­fra Con­struc­tion

NBM&CW - - CONTENTS - Ar Nilesh Gandhi

Con­crete, the won­der ma­te­rial that has shaped our sur­round­ings, was in­vented in the mid-18th cen­tury, and con­tin­ues to be the most widely used con­struc­tion ma­te­rial. Con­crete came to ar­chi­tects and de­sign­ers as a boon, to give form to their ex­pres­sions, and as a tool to ex­press cre­ativ­ity and bring an el­e­ment of per­son­al­iza­tion to their build­ings and struc­tures, with the ar­chi­tec­ture cater­ing to needs like im­age, state­ment, func­tion, and flex­i­bil­ity, for the end-user.

In­fra­struc­ture con­struc­tion, how­ever, is a dif­fer­ent ball game al­to­gether. Up­wards of 500 mil­lion met­ric tons of con­crete is con­sumed in In­dia, of which the quan­tum that is poured into in­fra­struc­ture con­struc­tions is mul­ti­ple times the vol­ume con­sumed by build­ing con­struc­tion. These in­clude roads, bridges, high­ways, fly­overs, met­ros, over ground and un­der­ground, pre­cast con­crete mem­bers et al. And with in­fra­struc­ture growth be­ing key to a coun­try’s growth, to “up” the lad­der of pros­per­ity, we shall be see­ing an ev­er­in­creas­ing vol­ume of such struc­tures defin­ing the cityscape. So, there is all the more rea­son to give fo­cus and deal cre­atively with these struc­tural el­e­ments as they have a shelf life of up to 70-100 years.

Aes­thetic eval­u­a­tions are a very sub­jec­tive as­pect; in­fra­struc­ture el­e­ments, while be­ing func­tional, need to fit into the en­vi­ron­ment and look el­e­gant. Their ap­pear­ance will al­ways lie along­side func­tion, econ­omy and con­struc­tion. Vis­ual ex­cel­lence needs to be eval­u­ated along with the de­sign ap­proach. Is­sues like re­la­tion to the site, scale and harmony in the con­text of the en­vi­ron­ment, cul­ture, color tone, and tex­ture, are to be given ad­e­quate im­por­tance, and High-Per­for­mance Con­crete (HPC) right­fully pro­vides all the re­quired as­sis­tance in giv­ing due jus­tice to all the aes­thet­i­cal pa­ram­e­ters for defin­ing the vis­ual char­ac­ter of spe­cific projects.

Con­crete, as we all know, be­ing strong in com­pres­sion and weak in ten­sion, led to the de­vel­op­ment of Re­in­forced Con­crete, which is formed by adding steel bars/ fibers or glass/plas­tic fibers, to cater to the ten­sile loads. As a com­bined en­tity giv­ing the re­quired strength to build struc­tures that

can stand the test of time, HPC pos­sesses higher strength than nor­mal con­crete.

New Age tech­nolo­gies have en­abled con­crete to achieve strength as high as 300 mega pas­cals (Mpa), 45000 pounds per square inch (psi). The high per­for­mance is on ac­count of higher strength, dura­bil­ity, and work­a­bil­ity, which gives ar­chi­tects and de­sign­ers tremen­dous aes­thetic flex­i­bil­i­ties. The higher per­for­mance is also due to ce­men­ti­tious ma­te­ri­als, fly ash, sil­ica fumes, slag and su­per plas­ti­cizer. The pro­por­tions are specif­i­cally de­signed to pro­vide high strength and low per­me­abil­ity.

HPC is de­void of the lim­i­ta­tions of con­ven­tional con­crete like mirco-crack­ing, and only needs care­ful de­sign­ing and pro­duc­tion. HPC is there­fore used in ar­eas of ex­treme ex­po­sure to chlo­rides, sul­phates and to counter the ef­fect of CO2 in the air. The ma­jor ad­van­tages of HPC be­ing re­duc­tion in the siz­ing of the struc­tures, it en­ables en­hanced de­sign flex­i­bil­ity and cre­ativ­ity. Slen­der siz­ing of the el­e­ments of­fers lesser space for tra­di­tional re­in­force­ment el­e­ments like steel, thereby, ne­ces­si­tat­ing use of spe­cial stain­less steel, which will con­tinue to dom­i­nate as fibers lack suf­fi­cient elas­tic­ity. Along with re­duc­tion in weight, they en­able long spans for pre­cast and ease of trans­porta­tion.

In­fra­struc­ture con­struc­tion pro­vides the much-re­quired repli­ca­bil­ity in pro­duc­tion, which gives im­mense op­por­tu­ni­ties to in­no­vate and de­sign de­sired struc­tures and el­e­ments. Even with high ini­tial mold costs, the over­all cost re­duces with mul­ti­ple reuses, thereby, negat­ing the high cost phe­nom­e­non. De­spite the mass scale pro­duc­tion ben­e­fits in cast­ing con­crete, the in­fra­struc­ture de­sign has by far been gov­erned by func­tional pa­ram­e­ters pre­dom­i­nantly, rather than aes­thet­ics. How­ever, the digital on­slaught has taken the de­sign to a com­pletely new level of ex­per­i­men­ta­tion, en­abled by HPC. The “why” for de­signer/ aes­thetic con­crete has its re­sponse in its ex­is­tence in the pub­lic do­main with the need and urge to up­grade the de­sign quo­tient of our in­fra­struc­ture fa­cil­i­ties.

The sur­face of con­crete is as im­por­tant as the con­crete it­self as it poses the “fin­ish” of the built el­e­ments. Form­work, there­fore, plays a very im­por­tant role in the cast­ing of con­crete to the de­sired fin­ish. And for de­sign­ers, it is ex­cit­ing to turn the struc­tural el­e­ments into el­e­ments of vis­ual ap­peal. In­fra Con­struc­tion con­sti­tutes ma­jorly of such el­e­ments, and HPC helps in keep­ing them ex­posed along with en­abling de­sign­ers to ex­per­i­ment with cre­ative out­puts, tak­ing shape of the form­work even with com­plex ge­ome­tries. Ad­di­tion of pig­ments or ag­gre­gates aids in giv­ing an in-situ self-colored op­tion, thereby adding a whole new aes­thetic di­men­sion.

Con­crete has given im­mense scope for de­sign­ers to ex­per­i­ment cre­atively with struc­tural de­sign, with as­ton­ish­ing re­sults. With biomimicry and bio­philia be­ing adopted in the mak­ing of new struc­tures, ver­sa­til­ity in con­crete is an ever-in­creas­ing phe­nom­e­non and HPC fills this need.

Ar­chi­tect Nilesh Gandhi, Me­tade­signIn­dia, M.Arch Project Man­age­ment, CEPT, Ahmed­abad, Phd (Hs.), LEED AP+, IGBC AP, EDGE Au­di­tor, GRIHA Trainer & Eval­u­a­tor, can be reached at nilesh.g@me­tade­

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